chlorophyll-a and chlorophyll-c

Besides the so-called 'green lineage' of eukaryotic photosynthetic organisms that include vascular plants, a huge variety of different algal groups exist that also harvest light by means of membrane intrinsic light harvesting proteins (Lhc). The main taxa of these algae are the Cryptophytes, Haptophytes, Dinophytes, Chromeridae and the Heterokonts, the latter including diatoms, brown algae, Xanthophyceae and Eustigmatophyceae amongst others. Despite the similarity in Lhc proteins between vascular plants and these algae, pigmentation is significantly different since no Chl b is bound, but often replaced by Chl c, and a large diversity in carotenoids functioning in light harvesting and/or photoprotection is present. Due to the presence of Chl c in most of the taxa the name 'Chl c-containing organisms' has become common, however, Chl b-less is more precise since some harbour Lhc proteins that only bind one type of Chl, Chl a. In recent years huge progress has been made about the occurrence and function of Lhc in diatoms, so-called fucoxanthin chlorophyll proteins (FCP), where also the first molecular structure became available recently. In addition, especially energy transfer amongst the unusual pigments bound was intensively studied in many of these groups. This review summarises the present knowledge about the molecular structure, the arrangement of the different Lhc in complexes, the excitation energy transfer abilities and the involvement in photoprotection of the different Lhc systems in the so-called Chl c-containing organisms. This article is part of a Special Issue entitled Light harvesting, edited by Dr. Roberta Croce.

Topics: Carotenoids; Chlorophyll; Eukaryota; Genes, Plant; Light-Harvesting Protein Complexes; Thylakoids

The chromalveolate hypothesis proposed by Cavalier-Smith (J Euk Microbiol 46:347-366, 1999) suggested that all the algae with chlorophyll c (heterokonts, haptophytes, cryptophytes, and dinoflagellates), as well as the ciliates, apicomplexans, oomycetes, and other non-photosynthetic relatives, shared a common ancestor that acquired a chloroplast by secondary endosymbiosis of a red alga. Much of the evidence from plastid and nuclear genomes supports a red algal origin for plastids of the photosynthetic lineages, but the number of secondary endosymbioses and the number of plastid losses have not been resolved. The issue is complicated by the fact that nuclear genomes are mosaics of genes acquired over a very long time period, not only by vertical descent but also by endosymbiotic and horizontal gene transfer. Phylogenomic analysis of the available whole-genome data has suggested major alterations to our view of eukaryotic evolution, and given rise to alternative models. The next few years may see even more changes once a more representative collection of sequenced genomes becomes available.

Topics: Chlorophyll; Chloroplasts; Eukaryota; Evolution, Molecular; Gene Transfer, Horizontal; Genome, Plastid; Genomics; Photosynthesis; Phylogeny; Plastids; Rhodophyta; Symbiosis; Time Factors

Attempts have been made to develop dye-sensitized solar cells based on the principles and materials of photosynthesis: We first tested photosynthetic pigments, carotenoids (Cars), chlorophylls (Chls) and their derivatives, to find sensitizers showing reasonable performance (photocurrent and conversion efficiency). We then tried to introduce the principles of photosynthesis, including electron transfer and energy transfer from Car to Phe a. Also, we tried co-sensitization using the pheophorbide (Phe) a and Chl c(2) pair which further enhanced the performance of the component sensitizers as follows: J(sc) = 9.0 + 13.8 --> 14.0 mA cm(-2) and eta = 3.4 + 4.6 --> 5.4%.

Topics: Carotenoids; Chlorophyll; Coloring Agents; Energy Transfer; Photosynthesis; Polyenes; Quantum Theory; Solar Energy

Chlorophyll c2 extracted from Sargassum horneri improved allergic symptoms in an animal model of allergic rhinitis. In the present study, we explored the efficacy of chlorophyll c2 in patients with seasonal allergic rhinitis. This was a single-center, randomized, double-blind placebo-controlled trial. Sixty-six patients aged 20-43 years, each with a 2-year history of seasonal allergic rhinitis, were randomly assigned to receive either a single daily dose (0.7 mg) of chlorophyll c2 or placebo for 12 weeks. The use of medications including H1-antihistamines and topical nasal steroids was recorded by rescue medication scores (RMSs) noted after 4, 8, and 12 weeks of treatment. Disease-specific quality of life was measured using the Japan Rhinitis Quality of Life Questionnaire (JRQLQ) both before and after 4, 8, and 12 weeks of treatment. The RMS at 8 weeks was significantly better in the chlorophyll c2 than the placebo group (mean RMS difference = -3.09; 95 % confidence interval = -5.96 to -0.22); the mean RMS at 4 weeks was only slightly better in the chlorophyll c2 group. The JRQLQ scores did not differ significantly between the two groups. Chlorophyll c2 would have a potential to be an alternative treatment for allergic rhinitis.

Topics: Adult; Chlorophyll; Double-Blind Method; Female; Humans; Japan; Male; Quality of Life; Rhinitis, Allergic, Seasonal; Sargassum; Single-Blind Method; Surveys and Questionnaires; Time Factors; Young Adult

Marine and terrestrial photosynthesis exhibit a schism in the accessory chlorophyll (Chl) that complements the function of Chl

Topics: Carbon-Oxygen Lyases; Chlorophyll; Chlorophyll A; Diatoms; Mutation; Photosynthesis; Phylogeny; Phytoplankton; Recombinant Proteins

Diatoms are a major group of algae, responsible for a quarter of the global primary production on our planet. Their adaptation to marine environments is ensured by their light-harvesting antenna - the fucoxanthin-chlorophyll protein (FCP) complex, which absorbs strongly in the blue-green spectral region. Although these essential proteins have been the subject of many studies, for a long time their comprehensive description was not possible in the absence of structural data. Last year, the 3D structures of several FCP complexes were revealed. The structure of an FCP dimer was resolved by crystallography for the pennate diatom Phaeodactylum tricornutum [W. Wang et al., Science, 2019, 363, 6427] and the structure of the PSII supercomplex from the centric diatom Chaetoceros gracilis, containing several FCPs, was obtained by electron microscopy [X. Pi et al., Science, 2019, 365, 6452; R. Nagao et al., Nat. Plants, 2019, 5, 890]. In this Perspective article, we evaluate how precisely these structures may account for previously published ultrafast spectroscopy results, describing the excitation energy transfer in the FCP from another centric diatom Cyclotella meneghiniana. Surprisingly, we find that the published FCP structures cannot explain several observations obtained from ultrafast spectroscopy. Using the available structures, and results from electron microscopy, we construct a trimer-based FCP model for Cyclotella meneghiniana, consistent with ultrafast experimental data. As a whole, our observations suggest that the structures from the proteins belonging to the FCP family display larger variations than the equivalent LHC proteins in plants, which may reflect species-specific adaptations or original strategies for adapting to rapidly changing marine environments.

Topics: Amino Acid Sequence; Chlorophyll; Chlorophyll A; Diatoms; Energy Transfer; Light-Harvesting Protein Complexes; Protein Conformation; Spectrometry, Fluorescence; Xanthophylls

Fucoxanthin-chlorophyll (Chl) a/c-binding proteins (FCPs) are light-harvesting pigment-protein complexes found in diatoms and brown algae. Due to the characteristic pigments, such as fucoxanthin and Chl c, FCPs can capture light energy in blue-to green regions. A pennate diatom Phaeodactylum tricornutum synthesizes a red-shifted form of FCP under weak or red light, extending a light-absorption ability to longer wavelengths. In the present study, we examined changes in light-harvesting and energy-transfer processes of P. tricornutum cells grown under white- and single-colored light-emitting diodes (LEDs). The red-shifted FCP appears in the cells grown under the green, yellow, and red LEDs, and exhibited a fluorescence peak around 714 nm. Additional energy-transfer pathways are established in the red-shifted FCP; two forms (F713 and F718) of low-energy Chl a work as energy traps at 77 K. Averaged fluorescence lifetimes are prolonged in the cells grown under the yellow and red LEDs, whereas they are shortened in the blue-LED-grown cells. Based on these results, we discussed the light-adaptation machinery of P. tricornutum cells involved in the red-shifted FCP.

Topics: Acclimatization; Adaptation, Physiological; Chlorophyll; Chlorophyll A; Chlorophyll Binding Proteins; Diatoms; Fluorescence; Light; Light-Harvesting Protein Complexes; Xanthophylls

# Deceased. Cryptophyte algae belong to a special group of oxygenic photosynthetic organisms containing pigment combination unique for plastids - phycobiliproteins and chlorophyll a/c-containing antenna. Despite the progress in investigation of morphological and ecological features, as well as genome-based systematics of cryptophytes, their photosynthetic apparatus remains poorly understood. The ratio of the photosystems (PS)s I and II is unknown and information on participation of the two antennal complexes in functions of the two photosystems is inconsistent. In the present work we demonstrated for the first time that the cryptophyte alga Rhodomonas salina had the PSI to PSII ratio in thylakoid membranes equal to 1 : 4, whereas this ratio in cyanobacteria and higher plants was known to be 3 : 1 and 1 : 1, respectively. Furthermore, it was established that contrary to the case of cyanobacteria the phycobiliprotein antenna represented by phycoerythrin-545 (PE-545) in R. salina was associated only with the PSII, which indicated specific spatial organization of these protein pigments within the thylakoids that did not facilitate interaction with the PSI.

Topics: Chlorophyll; Chlorophyll A; Cryptophyta; Light; Photosynthesis; Photosystem II Protein Complex; Phycoerythrin; Plastids; Thylakoids

Diatoms are abundant photosynthetic organisms in aquatic environments and contribute 40% of its primary productivity. An important factor that contributes to the success of diatoms is their fucoxanthin chlorophyll a/c-binding proteins (FCPs), which have exceptional light-harvesting and photoprotection capabilities. Here, we report the crystal structure of an FCP from the marine diatom

Topics: Chlorophyll; Chlorophyll A; Chlorophyll Binding Proteins; Diatoms; Energy Transfer; Light; Photosynthesis; Protein Structure, Quaternary; Thylakoids; Xanthophylls

Fucoxanthin chlorophyll (Chl) a/ c-binding proteins (FCPs) are unique light-harvesting antennas in diatoms. Recent time-resolved fluorescence analysis of photosystem I with FCP associated (PSI-FCPI) has mainly shown excitation energy transfer among Chls a from FCPI to PSI in tens of picoseconds. However, it remains unclear how each pigment, especially carotenoids and Chl c, in the FCPI is functionally related to the energy transfer in a femtosecond time range. Here, we reveal ultrafast excitation energy transfer mechanism in the PSI-FCPI preparations isolated from a diatom, Chaetoceros gracilis, by means of femtosecond time-resolved fluorescence spectroscopy with an upconversion system. Compared with the fluorescence lifetime components of PSI core-like complexes, the energy transfer of Chl c → Chl a in the FCPI was observed within hundreds of femtoseconds, and the energy in the FCPI was transferred to PSI in ∼2 ps. The comparative fluorescence analyses provide physical insights into the energy transfer machinery within FCPI and from FCPI to PSI.

Topics: Carotenoids; Chlorophyll; Chlorophyll A; Chlorophyll Binding Proteins; Diatoms; Energy Transfer; Fluorescence; Photosystem I Protein Complex; Spectrometry, Fluorescence; Xanthophylls

One of the most common anthropogenic impacts on river ecosystems is the effluent discharge from wastewater treatment plants. The effects of this contamination on stream biota may be intensified in Mediterranean climate regions, which comprise a drought period that leads to flow reduction, and ultimately to stagnant pools. To assess individual and combined effects of flow stagnation and sewage contamination, biofilm and gastropod grazers were used in a 5-week experiment with artificial channels to test two flow velocity treatments (stagnant flow/basal flow) and two levels of organic contamination using artificial sewage (no sewage input/sewage input). Stressors' effects were determined on biofilm total biomass and chlorophyll (Chl) content, on oxygen consumption and growth rate of the grazers (Theodoxus fluviatilis), and on the interaction grazer-biofilm given by grazer's feeding activity (i.e., biofilm consumption rate). The single effect of sewage induced an increase in biofilm biomass and Chl-a content, simultaneously increasing both grazers' oxygen consumption and their feeding activity. Diatoms showed a higher sensitivity to flow stagnation, resulting in a lower content of Chl-c. Combined stressors interacted antagonistically for biofilm total biomass, Chl-b contents, and grazers's feeding rate. The effect of sewage increasing biofilm biomass and grazing activity was reduced by the presence of flow stagnation (antagonist factor). Our findings suggest that sewage contamination has a direct effect on the functional response of primary producers and an indirect effect on primary consumers, and this effect is influenced by water flow stagnation.

Topics: Biofilms; Biomass; Biota; Chlorophyll; Conservation of Water Resources; Diatoms; Ecosystem; Rhodophyta; Rivers; Sewage; Waste Disposal Facilities; Water Pollutants; Water Supply

Topics: Calcium; Cell Movement; Chlorophyll; Chlorophyll A; Cryptophyta; Light; Photosystem II Protein Complex

Maintenance of energy balance under changeable light conditions is an essential function of photosynthetic organisms to achieve efficient photochemical reactions. Among the photosynthetic organisms, diatoms possess light-harvesting fucoxanthin chlorophyll (Chl) a/c-binding protein (FCP) as peripheral antennas. However, how diatoms regulate excitation-energy distribution between FCP and the two photosystem cores during light adaptation is poorly understood. In this study, we examined spectroscopic properties of a marine diatom Chaetoceros gracilis adapted in the dark and at photosynthetic photon flux density at 30 and 300 μmol photons m

Topics: Chlorophyll; Chlorophyll A; Chlorophyll Binding Proteins; Diatoms; Light; Pigments, Biological; Spectrometry, Fluorescence

We report the results of simple experiments which support the hypothesis that changes in ocean chemistry beginning in the Mesozoic Era resulted in an increase in the nutritional quality per mole of C and per cell of planktonic algal biomass compared to earlier phytoplankton. We cultured a cyanobacterium, a diatom, a dinoflagellate, and a green alga in media mimicking aspects of the chemistry of Palaeozoic and Mesozoic-Cenozoic oceans. Substantial differences emerged in the quality of algal biomass between the Palaeozoic and Mesozoic-Cenozoic growth regimes; these differences were strongly affected by interspecific interactions (i.e., the co-existence of different species alters responses to the chemistry of the medium). The change was in the direction of a Mesozoic-Cenozoic biomass enriched in protein per mole C, although cells contained less carbon overall. This would lead to a lower C:N ratio. On the assumption that Mesozoic-Cenozoic grazers' assimilation of total C was similar to that of their earlier counterparts, their diet would be stoichiometrically closer to their C:N requirement. This, along with an increase in mean cell size among continental shelf phytoplankton, could have helped to facilitate observed evolutionary changes in the Mesozoic marine fauna. In turn, increased grazing pressure would have operated as a selective force for the radiation of phytoplankton clades better equipped with antigrazing capabilities (sensu lato), as found widely in phytoplankton with biomineralization. Our results emphasize potential links between changing seawater chemistry, increased predation pressure and the rise to ecological dominance of chlorophyll a+c algae in Mesozoic oceans. The experiments also suggest a potential role for ocean chemistry in changes of marine trophic structure from the Palaeozoic to the later Mesozoic Era.

Topics: Biomass; Chlorophyll; Chlorophyll A; Oceans and Seas; Phytoplankton; Spectroscopy, Fourier Transform Infrared

Chlorophyll-a (Chl-a) was extracted from cyanobacterial cells and modified to methyl pyropheophorbide-a. The 3-vinyl-chlorin was transformed to zinc complex of the corresponding 3-acetyl-porphyrin. The zinc porphyrin was oxidized to give cis-7,8- and 17,18-dihydroxy-chlorins as well cis-7,8-cis-17,18-tetrahydroxybacteriochlorin. After zinc-demetallation, the isolated cis-7,8- and 17,18-diols were reduced at the 3-acetyl group and triply dehydrated under acidic conditions to afford two regioisomeric 3-vinyl-porphyrins, methyl divinyl-pyroprotopheophorbide-a possessing the 8-vinyl group and 17-propionate residue (one of the divinyl-protoChl-a derivatives) and methyl pyropheophorbide-c 1 possessing the 8-ethyl group and 17-acrylate residue (one of the Chl-c 1 derivatives), respectively. The resulting 7,8,17,18-tetrol was reduced and then acidically treated, giving five-fold dehydrated free base porphyrin, methyl pyropheophorbide-c 2 possessing the 3,8-divinyl groups and 17-acrylate residue (one of the Chl-c 2 derivatives). The visible absorption and fluorescence emission spectra of the three semi-synthetic 3-vinyl-porphyrins in dichloromethane were compared with those of the corresponding 8-ethyl-porphyrin bearing the 17-propionate residue, methyl pyroprotopheophorbide-a (one of the protoChl-a derivatives). The Soret and Qy absorption maxima were shifted to longer wavelengths with an increase of π-conjugation in a molecule: protoChl-a (8-CH2CH3/17-CH2CH2COOCH3) < divinyl-protoChl-a (8-CH=CH2/17-CH2CH2COOCH3) < Chl-c 1 (8-CH2CH3/17-CH=CHCOOCH3) < Chl-c 2 derivatives (8-CH=CH2/17-CH=CHCOOCH3). The 17(1),17(2)-dehydrogenation broadened the absorption bands. The emission maxima were bathochromically shifted in the same order. The reaction mechanism of the present dehydration indicates that the biosynthetic pathway of Chls-c would include the hydroxylation of the 17-propionate reside at the 17(1)-position and successive dehydration to the 17-acrylate residue.

Topics: Acrylates; Biosynthetic Pathways; Chlorophyll; Chlorophyll A; Optical Phenomena; Spectrometry, Fluorescence

The major light-harvesting pigment protein complex (fucoxanthin-chlorophyll-binding protein complex; FCP) was purified from a marine centric diatom, Chaetoceros gracilis, by mild solubilization followed by sucrose density gradient centrifugation, and then characterized. The dynamic light scattering measurement showed unimodality, indicating that the complex was highly purified. The amount of chlorophyll a (Chl a) bound to the purified FCP accounted for more than 60 % of total cellular Chl a. The complex was composed of three abundant polypeptides, although there are nearly 30 FCP-related genes. The two major components were identified as Fcp3 (Lhcf3)- and Fcp4 (Lhcf4)-equivalent proteins based on their internal amino acid sequences and a two-dimensional isoelectric focusing electrophoresis analysis developed in this work. Compared with the thylakoids, the FCP complex showed higher contents of fucoxanthin and chlorophyll c but lower contents of the xanthophyll cycle pigments diadinoxanthin and diatoxanthin. Fluorescence excitation spectra analyses indicated that light harvesting, rather than photosystem protection, is the major function of the purified FCP complex, which is associated with more than 60 % of total cellular Chl a. These findings suggest that the huge amount of Chl bound to the FCP complex composed of Lhcf3, Lhcf4, and an unidentified minor protein has a light-harvesting function to allow efficient photosynthesis under the dim-light conditions in the ocean.

Topics: Carrier Proteins; Chlorophyll; Chlorophyll A; Diatoms; Light; Light-Harvesting Protein Complexes; Photosystem II Protein Complex; Spectrometry, Fluorescence; Thylakoids; Xanthophylls

Phytoplankton dominant species and their light absorption properties during the blooms occurred in August 2013 in adjacent waters of the Changjiang Estuary were analyzed. The results showed that phytoplankton blooms broke out in 10 out of 34 investigation stations, among which diatom blooms occurred in 6 stations while 3 stations were predominated by dinoflagellate. Phytoplankton absorption coefficients of both bloom and non-bloom waters exhibited large variations, with respective ranges of 0.199-0.832 m(-1) and 0.012-0.109 m(-1), while phytoplankton specific absorption coefficients spanned much narrower range, with the average values of bloom and non-bloom waters being 0.023 and 0.035 m2 x mg(-1), respectively. When transitioned from bloom to non-bloom waters, the proportion of phytoplankton with larger cell size lowered while that of smaller phytoplankton elevated, causing a less extent of package effect and thus higher specific absorption coefficients. Distinctive absorption spectra were observed between different types of bloom (such as diatom and dinoflagellate blooms) with similar phytoplankton cell size, mostly attributed to distinctive accessory pigment composition. The ratios of diadinoxanthin and chlorophyll-c2 concentrations to chlorophyll-a concentration in dinoflagellate blooms were higher than those in diatom blooms, which largely contributed to the shoulder peaks at 465 nm in dinoflagellate blooms.

Topics: Chlorophyll; Chlorophyll A; Diatoms; Dinoflagellida; Estuaries; Eutrophication; Light; Phytoplankton; Xanthophylls

The fucoxanthin chlorophyll a/c-binding protein (FCP) is a unique antenna complex possessed by diatoms. Although FCP complexes have been isolated from various diatoms, there is no direct evidence for the existence of FCP associated with photosystem II (FCPII). Here, we report the isolation and spectroscopic characterization of FCPII complex from the diatom Chaetoceros gracilis. The FCPII complex was purified using sucrose centrifugation and anion-exchange chromatography. Clear-native PAGE and SDS-PAGE analyses revealed that the FCPII complex was composed of FCP-A oligomer and FCP-B/C trimer. Time-resolved fluorescence spectra of the FCPII complex were measured at 77 K. The characteristic lifetimes and fluorescence components were determined using global fitting analysis, followed by the construction of fluorescence decay-associated spectra (FDAS). FDAS exhibited fluorescence rises and decays, reflecting excitation energy transfer, with the time constants of 150 ps, 800 ps, and 2.9 ns. The long time constants are most likely attributed to the intercomplex excitation energy transfer between FCP-A oligomer and FCP-B/C trimer in the FCPII complex. The 5.6 ns FDAS likely originates from the final energy traps. In contrast, the FDAS exhibited no quenching component with any time constant. These results indicate that the FCPII complex is efficient in light harvesting and excitation energy transfer.

Topics: Centrifugation, Density Gradient; Chlorophyll; Chlorophyll A; Chromatography, Ion Exchange; Diatoms; Light; Photosynthesis; Photosystem II Protein Complex; Protein Multimerization; Xanthophylls

Femtosecond time-resolved transient absorption spectroscopy was performed on the chlorophyll a-chlorophyll c 2-peridinin-protein-complex (acpPC), a major light-harvesting complex of the coral symbiotic dinoflagellate Symbiodinium. The measurements were carried out on the protein as well on the isolated pigments in the visible and the near-infrared region at 77 K. The data were globally fit to establish inter-pigment energy transfer paths within the scaffold of the complex. In addition, microsecond flash photolysis analysis was applied to reveal photoprotective capabilities of carotenoids (peridinin and diadinoxanthin) in the complex, especially the ability to quench chlorophyll a triplet states. The results demonstrate that the majority of carotenoids and other accessory light absorbers such as chlorophyll c 2 are very well suited to support chlorophyll a in light harvesting. However, their performance in photoprotection in the acpPC is questionable. This is unusual among carotenoid-containing light-harvesting proteins and may explain the low resistance of the acpPC complex against photoinduced damage under even moderate light conditions.

Topics: Carotenoids; Chlorophyll; Chlorophyll A; Dinoflagellida; Light-Harvesting Protein Complexes

The fucoxanthin chlorophyll (Chl) a/c-binding protein (FCP) is responsible for excellent light-harvesting strategies that enable survival in fluctuating light conditions. Here, we report the light-harvesting and quenching states of two FCP complexes, FCP-A and FCP-B/C, isolated from the diatom Chaetoceros gracilis. Pigment analysis revealed that FCP-A is enriched in Chl c, whereas FCP-B/C is enriched in diadinoxanthin, reflecting differences in low-temperature steady-state absorption and fluorescence spectra of each FCP complex. Time-resolved fluorescence spectra were measured at 77 K, and the characteristic lifetimes were determined using global fitting analysis of the spectra. Tens of picosecond (ps) components revealed energy transfer to low-energy Chl a from Chls a and c, whereas the other components showed only fluorescence decay components with no concomitant rise components. The normalized amplitudes of hundreds of picosecond components were relatively 30% in the total fluorescence, whereas those of longest-lived components were 60%. The hundreds of picosecond components were assigned as excitation energy quenching, whereas the longest-lived components were assigned as fluorescence from the final energy traps. These results suggest that 30% of FCP complex forming quenching state and the other 60% of FCP complex forming light-harvesting state exist heterogeneously in each FCP fraction under continuous low-light condition.

Topics: Chlorophyll; Chlorophyll A; Diatoms; Light-Harvesting Protein Complexes; Spectrometry, Fluorescence; Temperature; Xanthophylls

First principles Born-Oppenheimer molecular dynamics of chlorophyll-c2 (chlc2) in liquid methanol is reported. The structure of the chromophore-methanol solution is characterized by non-symmetric solvation and by the displacement of a pentacoordinated Mg atom from the π macrocycle plane of chlc2. Non-symmetrical solvation is in keeping with experimental data reported for chlorophyll-a and bacteriochlorophyll-a indicating a preferential side of the π macrocycle for binding a fifth ligand. The average displacement of the Mg atom (0.38 Å) is similar to X-ray data on magnesium phthalocyanine (~0.45 Å) and ethyl chlorophyllide-a dihydrate crystals (0.39 Å). The displacement of Mg from the macrocycle plane influences the orientational order of the methanol molecules in the axial region and the results indicate that the face defined by the methoxycarbonyl moiety exhibits a solvatophobic behavior. The maximum of the Soret (B) band for chlc2 in liquid methanol (464 nm) is in good agreement with the experimental value (451 nm) and it is also very close to a recent result for chlc2 in liquid 2-methyl tetrahydrofuran (466 nm). Intramolecular hydrogen bonding involving the carboxyl and methoxycarbonyl moieties of chlc2 leads to a blueshift of ~20 nm of the B band maximum.

Topics: Chlorophyll; Crystallography, X-Ray; Electrons; Magnesium; Methanol; Molecular Dynamics Simulation

The controversial molecular identification of the so-called chlorophyll cCS-170 has been settled. Despite its relevance as a potential biomarker in the study of eukaryotic picophytoplankton, the structure of this chlorophyll remained so far uncertain. A full characterization by NMR, UV-vis, and ESI-MS is reported, revealing this chlorophyll as [7-methoxycarbonyl-8-vinyl]-protochlorophyllide a.

Topics: Chlorophyll; Chlorophyta; Electron Spin Resonance Spectroscopy; Molecular Structure; Protochlorophyllide

Pheophytinization of chlorophyll (Chl) c1, which was isolated from the diatom Chaetoceros gracilis, was kinetically analyzed under weakly acidic conditions, and was compared with that of protochlorophyllide (PChlide) a and chlorophyllide (Chlide) a. Chl c1 possessing a trans-acrylic acid residue at the 17-position exhibited slower pheophytinization kinetics than PChlide a and Chlide a, both of which possessed a propionic acid residue at the same position. The difference in pheophytinization properties between Chl c1 and (P)Chlide a was ascribable to the electronegativity of the 17-substituent in Chl c1 larger than that of (P)Chlide a due to the C17(1)-C17(2) double bond with the conjugated 17(2)-carboxy group in Chl c1. Demetalation kinetics of PChlide a was slower than that of Chlide a, which originated from the effect of the π-macrocyclic structures.

Topics: Acrylates; Chlorophyll; Chlorophyllides; Diatoms; Isomerism; Kinetics; Protochlorophyllide

The superfamily of light-harvesting complex (LHC) proteins is comprised of proteins with diverse functions in light-harvesting and photoprotection. LHC proteins bind chlorophyll (Chl) and carotenoids and include a family of LHCs that bind Chl a and c. Dinophytes (dinoflagellates) are predominantly Chl c binding algal taxa, bind peridinin or fucoxanthin as the primary carotenoid, and can possess a number of LHC subfamilies. Here we report 11 LHC sequences for the chlorophyll a-chlorophyll c(2)-peridinin protein complex (acpPC) subfamily isolated from Symbiodinium sp. C3, an ecologically important peridinin binding dinoflagellate taxa. Phylogenetic analysis of these proteins suggests the acpPC subfamily forms at least three clades within the Chl a/c binding LHC family; Clade 1 clusters with rhodophyte, cryptophyte and peridinin binding dinoflagellate sequences, Clade 2 with peridinin binding dinoflagellate sequences only and Clades 3 with heterokontophytes, fucoxanthin and peridinin binding dinoflagellate sequences.

Topics: Amino Acid Sequence; Carotenoids; Chlorophyll; Chlorophyll A; Dinoflagellida; Genes, Protozoan; Light-Harvesting Protein Complexes; Molecular Sequence Data; Phylogeny; Protozoan Proteins; Sequence Alignment

Dark-operative protochlorophyllide oxidoreductase, a nitrogenase-like enzyme, contains two [4Fe-4S] clusters, one in the L-protein ((BchL)(2)) and the other in the NB-protein ((BchN-BchB)(2)). The reduced NB-cluster in the NB-protein, which is ligated by 1Asp/3Cys residues, showed a broad S=3/2 electron paramagnetic resonance signal that is rather rare in [4Fe-4S] clusters. A 4Cys-ligated NB-cluster in the mutated variant BchB-D36C protein, in which the Asp36 was replaced by a Cys, gave a rhombic normal S=1/2 signal and lost the catalytic activity. The results suggest that Asp36 contributes to the low redox potential necessary to reduce protochlorophyllide.

Topics: Adenosine Triphosphate; Amino Acid Substitution; Aspartic Acid; Bacterial Proteins; Chlorophyll; Cysteine; Electron Spin Resonance Spectroscopy; Iron-Sulfur Proteins; Multigene Family; Nitrogenase; Oxidation-Reduction; Oxidoreductases Acting on CH-CH Group Donors; Rhodobacter capsulatus; Temperature

Brown algae of the genus Ectocarpus exhibit high levels of genetic diversity and variability in morphological and physiological characteristics. With the establishment of E. siliculosus as a model and the availability of a complete genome sequence, it is now of interest to analyze variability among different species, ecotypes, and strains of the genus Ectocarpus both at the genome and the transcriptome level.. We used an E. siliculosus gene expression microarray based on EST sequences from the genome-sequenced strain (reference strain) to carry out comparative genome hybridizations for five Ectocarpus strains: four E. siliculosus isolates (the male genome strain, a female strain used for outcrosses with the genome strain, a strain isolated from freshwater, and a highly copper-tolerant strain), as well as one strain of the sister species E. fasciculatus. Our results revealed significant genomic differences between ecotypes of the same species, and enable the selection of conserved probes for future microarray experiments with these strains. In the two closely related strains (a male and a female strain used for crosses), genomic differences were also detected, but concentrated in two smaller genomic regions, one of which corresponds to a viral insertion site.. The high variability between strains supports the concept of E. siliculosus as a complex of cryptic species. Moreover, our data suggest that several parts of the Ectocarpus genome may have evolved at different rates: high variability was detected particularly in transposable elements and fucoxanthin chlorophyll a/c binding proteins.

Topics: Chlorophyll; Chlorophyll A; Comparative Genomic Hybridization; Conserved Sequence; DNA, Plant; DNA, Ribosomal Spacer; Expressed Sequence Tags; Gene Expression Profiling; Gene Expression Regulation, Plant; Genetic Variation; Genome, Plant; Microarray Analysis; Phaeophyceae; Phylogeny

In deep lakes, water column stratification isolates the surface water from the deeper bottom layers, creating a three dimensional differentiation of the chemical, physical, biological and optical characteristics of the waters. Chromophoric dissolved organic matter (CDOM) and total suspended solids (TSS) play an important role in the attenuation of ultraviolet and photosynthetically active radiation. In the present analysis of spectral irradiance, we show that the wavelength composition of the metalimnetic visible irradiance was influenced by epilimnetic spatial distribution of CDOM. We found a low occurrence of blue-green photons in the metalimnion where epilimnetic concentrations of CDOM are high. In this field study, the spatial variation of the spectral irradiance in the metalimnion correlates with the observed metalimnetic concentrations of chlorophyll a as well as chlorophyll a : chlorophyll b/c ratios. Dissolved oxygen, pH, and nutrients trends suggest that chlorophyll a concentrations were representative of the phytoplankton biomass and primary production. Thus, metalimnetic changes of spectral irradiance may have a direct impact on primary production and an indirect effect on the spatial trends of pH, dissolved oxygen, and inorganic nutrients in the metalimnion.

Topics: Biomass; Chlorophyll; Chlorophyll A; Hydrogen-Ion Concentration; Oxygen; Phytoplankton; Seasons; Ultraviolet Rays; Water

Light harvesting complex (LHC) proteins function in photosynthesis by binding chlorophyll (Chl) and carotenoid molecules that absorb light and transfer the energy to the reaction center Chl of the photosystem. Most research has focused on LHCs of plants and chlorophytes that bind Chl a and b and extensive work on these proteins has uncovered a diversity of biochemical functions, expression patterns and amino acid sequences. We focus here on a less-studied family of LHCs that typically bind Chl a and c, and that are widely distributed in Chl c-containing and other algae. Previous phylogenetic analyses of these proteins suggested that individual algal lineages possess proteins from one or two subfamilies, and that most subfamilies are characteristic of a particular algal lineage, but genome-scale datasets had revealed that some species have multiple different forms of the gene. Such observations also suggested that there might have been an important influence of endosymbiosis in the evolution of LHCs.. We reconstruct a phylogeny of LHCs from Chl c-containing algae and related lineages using data from recent sequencing projects to give ~10-fold larger taxon sampling than previous studies. The phylogeny indicates that individual taxa possess proteins from multiple LHC subfamilies and that several LHC subfamilies are found in distantly related algal lineages. This phylogenetic pattern implies functional differentiation of the gene families, a hypothesis that is consistent with data on gene expression, carotenoid binding and physical associations with other LHCs. In all probability LHCs have undergone a complex history of evolution of function, gene transfer, and lineage-specific diversification.. The analysis provides a strikingly different picture of LHC diversity than previous analyses of LHC evolution. Individual algal lineages possess proteins from multiple LHC subfamilies. Evolutionary relationships showed support for the hypothesized origin of Chl c plastids. This work also allows recent experimental findings about molecular function to be understood in a broader phylogenetic context.

Topics: Chlorophyll; Cryptophyta; Dinoflagellida; Evolution, Molecular; Genome; Haptophyta; Light-Harvesting Protein Complexes; Phylogeny; Pigments, Biological; Sequence Alignment; Stramenopiles

During the Mesozoic Era, dinoflagellates, coccolithophorids and diatoms became prominent primary producers in the oceans, succeeding an earlier biota in which green algae and cyanobacteria had been proportionally more abundant. This transition occurred during an interval marked by increased sulfate concentration in seawater. To test whether increasing sulfate availability facilitated the evolutionary transition in marine phytoplankton, the cyanobacterium Synechococcus sp., the green alga Tetraselmis suecica and three algae containing chlorophyll a+c (the diatom Thalassiosira weissflogii, the dinoflagellate Protoceratium reticulatum and the coccolithophorid Emiliania huxleyi) were grown in media containing 1, 5, 10, 20, or 30 mm SO(4) (2-) . The cyanobacterium and the green alga showed no growth response to varying [SO(4) (2-) ]. By contrast, the three chlorophyll a+c algae showed improved growth with higher [SO(4) (2-) ], but only up to 10 mm. The chlorophyll a+c algae, but not the green alga or cyanobacterium, also showed lower C:S with higher [SO(4) (2-) ]. When the same experiment was repeated in the presence of a ciliate predator (Euplotes sp.), T. suecica and T. weissflogii increased their specific growth rate in most treatments, whereas the growth rate of Synechococcus sp. was not affected or decreased in the presence of grazers. In a third experiment, T. suecica, T. weissflogii, P. reticulatum and Synechococcus sp. were grown in conditions approximating modern, earlier Paleozoic and Proterozoic seawater. In these treatments, sulfate availability, nitrogen source, metal availability and Pco(2) varied. Monospecific cultures exhibited their highest growth rates in the Proterozoic treatment. In mixed culture, T. weissflogii outgrew other species in modern seawater and T.suecica outgrew the others in Paleozoic water. Synechococcus sp. grew best in Proterozoic seawater, but did not outgrow eukaryotic species in any treatment. Collectively, our results suggest that secular increase in seawater [SO(4) (2-) ] may have facilitated the evolutionary expansion of chlorophyll a+c phytoplankton, but probably not to the exclusion of other biological and environmental factors.

Topics: Biological Evolution; Chlorophyll; Chlorophyll A; Chlorophyta; Culture Techniques; Environment; Euplotes; Microalgae; Seawater; Sulfates; Synechococcus

Chlorophyll(Chl)-c pigments in algae, diatoms and some prokaryotes are characterized by the fully conjugated porphyrin π-system as well as the acrylate residue at the 17-position. The precise structural characterization of Chl-c(3) from the haptophyte Emiliania huxleyi was performed. The conformations of the π-conjugated peripheral substituents, the 3-/8-vinyl, 7-methoxycarbonyl and 17-acrylate moieties were evaluated, in a solution, using nuclear Overhauser enhancement correlations and molecular modeling calculations. The rotation of the 17-acrylate residue was considerably restricted, whereas the other three substituents readily rotated at ambient temperature. Moreover, the stereochemistry at the 13²-position was determined by combination of chiral high-performance liquid chromatography (HPLC) with circular dichroism (CD) spectroscopy. Compared with the CD spectra of the structurally related, synthetic (13²R)- and (13²S)-protochlorophyllide(PChlide)-a, naturally occurring Chl-c₃ had exclusively the (13²R)-configuration. To elucidate this natural selection of a single enantiomer, we analyzed the three major Chl-c pigments (Chl-c₁, c₂ and c₃) in four phylogenetically distinct classes of Chl-c containing algae, i.e., heterokontophyta, dinophyta, cryptophyta and haptophyta using chiral HPLC. All the photosynthetic organisms contained only the (13²R)-enantiomerically pure Chls-c, and lacked the corresponding enantiomeric (13²S)-forms. Additionally, Chl-c₂ was found in all the organisms as the common Chl-c. These results throw a light on the biosynthesis as well as photosynthetic function of Chl-c pigments: Chl-c₂ is derived from 8-vinyl-PChlide-a by dehydrogenation of the 17-propionate to acrylate residues as generally proposed, and the (13²R)-enantiomers of Chls-c function as photosynthetically active, light-harvesting pigments together with the principal Chl-a and carotenoids.

Topics: Chlorophyll; Haptophyta; Molecular Structure; Stereoisomerism

Chlorophylls (Chls)-a and -c(2) are identified and characterized in fucoxanthin chlorophyll-a/c(2) protein (FCP) complexes in the trimeric (FCPa(trim)) and oligomeric (FCPb(olig)) forms of FCP from the diatom Cyclotella meneghiniana using resonance Raman (RR) spectroscopy. Importantly, two different Chl-c(2)s are identified in both FCPa(trim) and FCPb(olig) from their signature ring-breathing modes at approximately 1360 cm(-1). In addition, the C13(1)-keto carbonyl peaks indicate the presence of more than four Chl-a's in both FCP complexes and are broadly classified into three groups with strong, medium and weak external hydrogen bonds. Together, they provide the strongest spectroscopic evidence so far that there may be up to double the number of pigments previously estimated at 4Fx:4Chl-a:1Chl-c(2) per FCP monomer. Careful analysis of the protein sequences also strongly support the higher pigment content by showing that at least six Chl-a, and one Chl-b, binding sites found in LHCII are retained in the FCPs. The relative enhancement of the RR bands for 406.7 versus 413.1 nm further allows some distinction of blue- versus red-absorbing Chl-a's, respectively. Further differences between the Chls in FCPb(olig) and FCPa(trim) are present in the amino-acid sequences and the RR signals. Information about the Chl-binding sites, complemented by information about the structures and interactions of the Chls are used to characterize their local environments, and assign pigment locations (and functions) in FCPb(olig) and FCPa(trim), which along with the earlier characterization of the carotenoids (J. Phys. Chem. B. 112 (2009) 12565-12574) provide a first (global) framework for pigment organization in FCP.

Topics: Amino Acid Sequence; Binding Sites; Chlorophyll; Chlorophyll A; Diatoms; Models, Molecular; Molecular Sequence Data; Pigments, Biological; Sequence Alignment; Spectrum Analysis, Raman; Xanthophylls

The biomonitoring of pesticide pollution in streams and rivers using algae such as diatoms remains difficult. The responses of diatom communities to toxic stress in stream water are disturbed by the variations of environmental parameters. In this study, periphytic algae collected in situ were exposed under controlled conditions to two major herbicides used in French agriculture (isoproturon and s-metolachlor). Three exposure regimes were tested: 5 and 30 microg L(-1) for 6 days and 30 microg L(-1) for 3 days followed by a recovery period of 3 days. The algal biomasses were assessed from pigment concentrations (chlorophyll a and c) and from live cell density. The highest concentration (30 microg L(-1)) of isoproturon inhibited the biomass increase statistically significantly. In periphyton exposed to 5 and 30 microg L(-1) of s-metolachlor, chlorophyll c concentration and live cell density were also statistically significantly lower than in the control. Periphyton left to recover after reduced exposure duration (3 days) showed higher growth rates after treatment with s-metolachlor than with isoproturon. Taxonomic identifications showed that species like Melosira varians, Nitzschia dissipata and Cocconeis placentula were not affected by the herbicide exposure. Other species like Eolimna minima and Navicula reichardtiana were more sensitive. Studying diatoms according to their trophic mode showed that facultative heterotroph species were statistically significantly favoured by isoproturon exposure at the highest concentration. Results obtained with s-metolachlor exposure showed a disturbance of cell multiplication rather than that of photosynthesis. These results suggest that photosynthesis inhibitors like isoproturon favour species able to survive when the autotroph mode is inhibited.

Topics: Acetamides; Biomass; Cell Count; Chlorophyll; Chlorophyll A; Chromatography, High Pressure Liquid; Diatoms; Environmental Monitoring; Fresh Water; Herbicides; Phenylurea Compounds; Rivers; Solid Phase Extraction; Statistics, Nonparametric; Temperature; Water Pollutants, Chemical

Chlorophyll (Chl)-c1 and Chl-c2 were extracted from a commercially available diatom Chaetoseros calcitrans, and the former (8-ethyl) and the latter (8-vinyl) were efficiently separated by reverse-phase HPLC using a polymeric octadecylsilyl column to afford analytically pure compounds in an amount adequate for further chemical modification. The conformation of the unique acrylate moiety at the 17-position of isolated Chls-c in THF was unambiguously determined to be "cisoid" around the C17-C17(1) bond using 1H-1H NOE correlations: C17(1)=C17(2) was on the same side as C17=C18. Interestingly, correlations originating from the "transoid" conformer could not be observed under the present NMR conditions, indicating that the rotation of the acrylate was considerably restricted. To elucidate the function of the rigid acrylate in Chls-c, we examined their electronic absorption properties using two synthetic types of esters possessing a porphyrin pi-system: acrylate-type (17-CH=CH-COOR) prepared by esterification of natural Chl-c1 and Chl-c2, and propionate-type (17-CH2-CH2-COOR) by 17,18-oxidation of natural Chl-a and its 8-vinyl analog. The Soret absorption bands at around 450 nm of the acrylate-type were red-shifted and broadened more than those of the propionate-type. Consequently, the unique acrylate in Chls-c serves as an aid for expanding the absorption region around 400-500 nm in order to capture intense irradiation from the sun for photosynthesis.

Topics: Acrylates; Chlorophyll; Diatoms; Electrons; Models, Molecular; Molecular Structure; Stereoisomerism

Photosynthetic supercomplexes from the cryptophyte Rhodomonas CS24 were isolated by a short detergent treatment of membranes from the cryptophyte Rhodomonas CS24 and studied by electron microscopy and low-temperature absorption and fluorescence spectroscopy. At least three different types of supercomplexes of photosystem I (PSI) monomers and peripheral Chl a/c(2) proteins were found. The most common complexes have Chl a/c(2) complexes at both sides of the PSI core monomer and have dimensions of about 17x24 nm. The peripheral antenna in these supercomplexes shows no obvious similarities in size and/or shape with that of the PSI-LHCI supercomplexes from the green plant Arabidopsis thaliana and the green alga Chlamydomonas reinhardtii, and may be comprised of about 6-8 monomers of Chl a/c(2) light-harvesting complexes. In addition, two different types of supercomplexes of photosystem II (PSII) dimers and peripheral Chl a/c(2) proteins were found. The detected complexes consist of a PSII core dimer and three or four monomeric Chl a/c(2) proteins on one side of the PSII core at positions that in the largest complex are similar to those of Lhcb5, a monomer of the S-trimer of LHCII, Lhcb4 and Lhcb6 in green plants.

Topics: Chlorophyll; Chlorophyll A; Chromatography, Gel; Cryptophyta; Dimerization; Electrophoresis, Polyacrylamide Gel; Mass Spectrometry; Microscopy, Electron; Photosystem I Protein Complex; Photosystem II Protein Complex; Spectrum Analysis; Temperature

In the present study we report that in the diatom Cyclotella meneghiniana the diatoxanthin-dependent non-photochemical quenching of chlorophyll fluorescence (NPQ) is heterogeneous and consists of three different components. (i) A transient NPQ component that generates immediately upon illumination, depends on the transthylakoid proton gradient as well as on the light intensity, and is modulated by the initial diatoxanthin content of the cells. It is located in the antenna complexes of C. meneghiniana and is comparable with the transient NPQ observed in vascular plants. (ii) A steady-state NPQ component is observed during later stages of the high-light illumination and depends on the diatoxanthin content formed by the light-activated diadinoxanthin cycle. (iii) A fast relaxing NPQ component is seen upon a transition of high-light-illuminated cells to complete darkness. This component relaxes within a time frame of tens of seconds and its extent is correlated with the amount of diatoxanthin formed during the phase of actinic illumination. It cannot be observed in dithiothreitol-treated cells where the de-epoxidation of diadinoxanthin to diatoxanthin is suppressed. The fast relaxing component can be interpreted as a relaxation of part of the steady-state NPQ. The different diatoxanthin-dependent components are characterized by different quenching efficiencies of diatoxanthin. Diatoxanthin involved in the transient NPQ exhibits a 2-fold higher quenching efficiency compared with diatoxanthin participating in the steady-state NPQ. It is proposed that the different quenching efficiencies of diatoxanthin are caused by the existence of different diatoxanthin pools within the antenna system of C. meneghiniana.

Topics: beta Carotene; Chlorophyll; Diatoms; Fluorescence; Light; Photosynthesis; Signal Transduction; Time Factors; Xanthophylls

Thermal resistance of the coral-zooxanthellae symbiosis has been associated with chronic photoinhibition, increased antioxidant activity and protein repair involving high demands of nitrogen and energy. While the relative importance of heterotrophy as a source of nutrients and energy for cnidarian hosts, and as a means of nitrogen acquisition for their zooxanthellae, is well documented, the effect of feeding on the thermal sensitivity of the symbiotic association has been so far overlooked. Here we examine the effect of zooplankton feeding versus starvation on the bleaching susceptibility and photosynthetic activity of photosystem II (PSII) of zooxanthellae in the scleractinian coral Stylophora pistillata in response to thermal stress (daily temperature rises of 2-3 degrees C) over 10 days, employing pulse-amplitude-modulated chlorophyll fluorometry. Fed and starved corals displayed a decrease in daily maximum potential quantum yield (F (v)/F (m)) of PSII, effective quantum yield (F/F (m)') and relative electron transport rates over the course of 10 days. However after 10 days of exposure to elevated temperature, F (v)/F (m) of fed corals was still 50-70% higher than F (v)/F (m) of starved corals. Starved corals showed strong signs of chronic photoinhibition, which was reflected in a significant decline in nocturnal recovery rates of PSII relative to fed corals. This was paralleled by the progressive inability to dissipate excess excitation energy via non-photochemical quenching (NPQ). After 10 days, NPQ of starved corals had decreased by about 80% relative to fed corals. Feeding treatment had no significant effect on chlorophyll a and c (2) concentrations and zooxanthellae densities, but the mitotic indices were significantly lower in starved than in fed corals. Collectively the results indicate that exogenous food may reduce the photophysiological damage of zooxanthellae that typically leads to bleaching and could therefore play an important role in mediating the thermal resistance of some corals.

Topics: Acclimatization; Animals; Anthozoa; Biomass; Chlorophyll; Chlorophyll A; Fluorometry; Hot Temperature; Mitotic Index; Photosynthesis; Photosystem II Protein Complex; Population Density; Stress, Physiological; Symbiosis; Zooplankton

Thylakoid membranes of the cryptophyte Chroomonas sp. strain LT were solubilized with dodecyl-beta-maltoside and subjected to sucrose density gradient centrifugation. The four pigment protein complexes obtained were subsequently characterized by absorption and fluorescence spectroscopy, SDS-PAGE, and Western immunoblotting using antisera against the chlorophyll a/c-binding proteins of the marine cryptophyte Cryptomonas maculata and the reaction-center protein D2 of photosystem II of maize. Band 1 consisted mainly of free pigments, phycobiliproteins, and chlorophyll-a/c-binding proteins. Band 2 represented a major chlorophyll a/c-binding protein fraction. A mixture of photosystem II and photosystem I proteins comprised band 3, whereas band 4 was enriched in proteins of photosystem I. Western immunoblotting demonstrated the presence of chlorophyll a/c-binding proteins and their association with photosystem I in band 4. Phosphorylation experiments showed that chlorophyll a/c-binding proteins became phosphorylated. Negative staining electron microscopy of band B4 revealed photosystem I particles with dimensions of 22 nm. Our work showed that PSI-LHCI complexes of cryptophytes are similar to those of Chlamydomonas rheinhardtii, the diatom Phaeodactylum tricornutum, and higher plants.

Topics: Centrifugation, Density Gradient; Chlorophyll; Chlorophyll A; Cryptophyta; Dimerization; Light-Harvesting Protein Complexes; Maltose; Microscopy, Electron; Peptides; Phosphorylation; Photosystem I Protein Complex

We screened in vitro antiviral activity against a salmonid pathogenic virus, infectious hematopoietic necrosis virus (IHNV), from the extracts of a total of 342 species of marine algae collected from the Japanese coastline. The anti-IHNV activity was found primarily in MeOH extracts, and the extract from one marine brown alga in particular, Eisenia bicyclis, showed high anti-IHNV activity. The anti-IHNV compound was isolated and purified as MC15 from the E. bicyclis extract, and the chemical structure was determined by several spectrometric analyses. The antiviral compound was proved to be a chlorophyll c2 derivative lacking the metal ion Mg(2+). MC15 showed similar antiviral activity against other salmonid enveloped viruses such as Paralichthys olivaceus virus and Oncorhynchus masou virus, and stability against any pH and temperatures up to 100 degrees C. No cytotoxicity was observed at up to 5 microg/ml. The antiviral mechanism of MC15 appears to be direct inactivation of the viral particles. A time course study showed that the inactivation of IHNV was completed within 40 min when 200 PFU of IHNV was reacted with MC15 at 800 ng/ml.

Topics: Animals; Cell Line; Chlorophyll; Hot Temperature; Hydrogen-Ion Concentration; Infectious hematopoietic necrosis virus; Japan; Marine Biology; Oceans and Seas; Phaeophyceae; Salmonidae; Time Factors; Viral Plaque Assay; Virus Inactivation

Photosynthetic eukaryotes contain primary, secondary or tertiary plastids, depending on the source of the organelle (a cyanobacterium or a photosynthetic eukaryote). Plastid phylogeny is relatively well investigated, but molecular phylogenies have conflicted as a function of gene choice, taxon-representations, and analytical method. To better understand the influences of these variables, we performed analyses of a multi-gene data set based on 62 plastid-associated genes of 15 taxa representing the major plastid lineages. In an attempt to distinguish phylogenetic signal from non-phylogenetic patterns, we analyzed the data using a wide range of phylogenetic methods and examined the effect of covarion evolution and compositional bias. The data suggest that the chlorophyll c-containing plastids are monophyletic and acquired their plastids from the red algae after the emergence of the Cyanidiales. The relationships among chl c-containing plastids are particularly hard to resolve. This is the largest data set used for this purpose; the analyses show that cryptophyte plastids are sister to other chl c-containing plastids, and haptophyte and peridinin-containing dinoflagellate plastids are closely related.

Topics: Chlorophyll; Genome; Nucleotides; Photosynthesis; Phylogeny; Plastids; Proteins; Triticum

Recent multi-gene phylogenetic analyses of plastid-encoded genes have recovered a robust monophyly of chlorophyll-c containing plastids (Chl-c palstids) in cryptophytes, haptophytes, photosynthetic stramenopiles, and dinoflagellates. However, all the plastid multi-gene phylogenies published to date utilized the "linked" model, which ignores the heterogeneity of sequence evolution across genes in alignments. Both empirical and simulation studies show that, compared to the linked model, the "unlinked" model, which accounts for gene-specific evolution, can greatly improve multi-gene estimations. Here we newly sequenced 46 genes of Chl-c plastids, and examined the Chl-c plastid evolution by multi-gene analyses under the unlinked model. Unexpectedly, Chl-c plastid monophyly received only low to medium support in our analyses based on multi-gene data sets including up to 4829 alignment positions. Although we systematically surveyed and excluded the genes that could mislead estimation, the (inconclusive) support for Chl-c plastid monophyly was not significantly altered. We conclude that the estimates from the current plastid-encoded gene data are insufficient to resolve Chl-c plastid evolution with confidence, and are highly affected by genes subjected to the analyses, and methods for tree reconstruction applied. Thus, future data analyses of larger multi-gene data sets, preferentially under the unlinked model, are required to conclusively understand Chl-c plastid evolution.

Topics: Animals; Chlorophyll; Ciliophora; Dinoflagellida; Evolution, Molecular; Models, Biological; Models, Genetic; Multigene Family; Phylogeny; Plastids

The expression of the glutathione peroxidase homologous gene Gpxh, known to be specifically induced by the formation of singlet oxygen (1O2), was analyzed in cells of Chlamydomonas reinhardtii exposed to environmental conditions causing photoinhibition. Illumination with high light intensities, leading to an increased formation of 1O2 in photosystem II, continuously induced the expression of Gpxh in cell for at least 2 h. Phenolic herbicides like dinoterb, raise the rate of 1O2 formation by increasing the probability of charge recombination in photosystem II via the formation of the primary radical pair and thereby 3P680 formation (Fufezan C et al. 2002, FEBS Letters 532, 407-410). In the presence of dinoterb the light-induced loss of the D1 protein in C. reinhardtii was increased and the high light-induced Gpxh expression was further stimulated. DCMU, a urea-type herbicide, causing reduced 1O2 generation in photosystem II, protected the D1 protein slightly against degradation and downregulated the expression of the Gpxh gene compared to untreated cells exposed to high light intensities. This indicates that the Gpxh expression is induced by 1O2 under environment conditions causing photoinhibition.

Topics: Animals; Chlamydomonas reinhardtii; Chlorophyll; Electron Spin Resonance Spectroscopy; Gene Expression Regulation; Glutathione Peroxidase; Herbicides; Light; Photosystem II Protein Complex; Protozoan Proteins; Singlet Oxygen; Spin Labels; Spin Trapping; Spinacia oleracea; Thylakoids; Up-Regulation

Carbonyl carotenoids are important constituents of the antenna complexes of marine organisms. These carotenoids possess an excited state with a charge-transfer character (intramolecular charge transfer state, ICT), but many details of the carotenoid to chlorophyll energy transfer mechanisms are as yet poorly understood. Here, we employ femtosecond transient absorption spectroscopy to study energy transfer pathways in the intrinsic light-harvesting complex (LHC) of dinoflagellates, which contains the carbonyl carotenoid peridinin. Carotenoid to chlorophyll energy transfer efficiency is about 90% in the 530-550 nm region, where the peridinin S2 state transfers energy with an efficiency of 25-50%. The rest proceeds via the S1/ICT channel, and the major S1/ICT-mediated energy transfer pathway utilizes the relaxed S1/ICT state and occurs with a time constant of 2.6 ps. Below 525 nm, the overall energy transfer efficiency drops because of light absorption by another carotenoid, diadinoxanthin, that contributes only marginally to energy transfer. Instead, its role is likely to be photoprotection. In addition to the peridinin-Chl-a energy transfer, it was shown that energy transfer also occurs between the two chlorophyll species in LHC, Chl-c2, and Chl-a. The time constant characterizing the Chl-c2 to Chl-a energy transfer is 1.4 ps. The results demonstrate that the properties of the S1/ICT state specific for carbonyl carotenoids is the key to ensure the effective harvesting of photons in the 500-600 nm region, which is of vital importance to underwater organisms.

Topics: Carotenoids; Chlorophyll; Chlorophyll A; Energy Transfer; Eukaryota; Light-Harvesting Protein Complexes; Marine Biology; Protons; Protozoan Proteins; Spectrum Analysis

The marine diatom Haslea ostrearia was cultured under light of different qualities, white (WL), blue (BL), green (GL), yellow (YL), red (RL), and far-red (FRL) and at two irradiance levels, low and high (20 and 100 micromolphotonsm(-2)s(-1), respectively). The effects of the different light regimes were studied on growth, pigment content, and photosynthesis, estimated by the modulated fluorescence of chlorophyll, as relative electron transport rate (rETR). For all the light qualities studied, growth rates were higher at high irradiance. Compared to the corresponding WL controls, growth was higher in BL and lower in YL at low irradiance, and lower in YL and GL at high irradiance. Except for YL, almost all the pigment contents of the cells were lower at high irradiance. At low irradiance, cell pigment contents (chlorophyll a and c, fucoxanthin) and pigment ratios (in function of chlorophyll a) were lower in YL, RL, and FRL. Whatever the irradiance level, the maximum PSII quantum efficiency (F(v)/F(m) remained almost constant for WL, BL, and GL. Other fluorescence parameters (photochemical quenching, rETR(max), and alpha, the maximum light utilization coefficient) were lower in GL, YL, RL, and FRL, at low irradiance. Although not statistically significant, BL caused an increase in these fluorescence parameters. These findings are interpreted as evidence that inverse chromatic acclimation occurs in diatoms.

Topics: Acclimatization; Carotenoids; Chlorophyll; Chlorophyll A; Color; Diatoms; Electron Transport; Fluorescence; Light; Photosynthesis; Pigmentation

Two new methods for analysing the pigment composition of photosynthetic samples have been developed during the last few years. One, called the spectral reconstruction method, uses linear least-squares fitting, while the other, named the Gauss-peak spectra method, entails non-linear optimisation; each has some advantages over the other, but both use a large number of data points and surpass the traditional method which uses absorbance at a few wavelengths. In order to make the new methods transparent to experimentalists who are not well versed in statistical analysis, curve fitting and interpolation, simple procedures are described for implementing the methods with the aid of a spreadsheet. The problem of analysing a sample containing chlorophyll c, which is difficult to isolate in a form sufficiently pure to serve as an analytical standard, is also briefly addressed.

Topics: Avena; Chlorophyll; Diatoms; Least-Squares Analysis; Linear Models; Nonlinear Dynamics; Phaeophyceae; Photosynthesis; Pigments, Biological; Plant Leaves; Spectrophotometry

In the present study we investigate how intraspecific (density-dependent) competition for nutrients by the diatom Nitzschia microcephala affects the level of oxidative stress in the algal cells as well as their production of pigments and thiamine. N. microcephala was grown in three different densities until the stationary growth phase was reached. Throughout the experiment, growth rate was negatively related to cell density. Superoxide dismutase activity, protein thiol, and diatoxanthin concentrations indicated increasing oxidative stress with increasing cell density, which was most probably caused by nutrient depletion of the medium. Pigment contents per cell (except for diatoxanthin) decreased with increasing cell density. N. microcephala was able to synthesize thiamine and its thiamine content per cell increased in concert with cell density. In comparison, the dinoflagellate Amphidinium carterae was unable to synthesize thiamine. These results suggest that cells of N. microcephala subjected to higher competition and lower growth rates have a lower carotenoid content and a higher thiamine content. If such responses would occur in nature as well, eutrophication (higher cell densities) may alter the quality of microalgae as food items for higher trophic levels not only by species shifts in the phytoplankton, but also by changes in the cellular nutritional value within species.

Topics: Animals; Chlorophyll; Chlorophyll A; Diatoms; Dinoflagellida; Eutrophication; Oxidative Stress; Sulfhydryl Compounds; Superoxide Dismutase; Thiamine; Xanthophylls

Using circular dichroism (CD) spectroscopy, the stereochemistry at C-13(2) of members of the chlorophyll (Chl) c family, namely Chls c(1), c(2), c(3) and [8-vinyl]-protochlorophyllide a (Pchlide a) was determined. By comparison with spectra of known enantiomers, all Chl c members turned out to have the (R) configuration, which is in agreement with considerations drawn from chlorophyll biosynthesis. Except for a double bond in the side chain at C-17, the chemical structure of Chl c(1) is identical with Pchlide a, the natural substrate of the light-dependent NADPH:protochlorophyllide oxidoreductase (POR). Thus, lack of binding to the active site due to the wrong configuration at C-13(2), which had been proposed previously, cannot be an explanation for inactivity of Chl c in this enzymic reaction. Our results show rather that Chl c(1) is a competitive inhibitor for this enzyme, tested with Pchlide a and Zn-protopheophorbide a (Zn-Ppheide a) as substrates.

Topics: Chlorophyll; Chlorophyll A; Circular Dichroism; Oxidoreductases; Oxidoreductases Acting on CH-CH Group Donors; Phaeophyceae; Protein Conformation; Protochlorophyllide

Phytoplankton is a nineteenth century ecological construct for a biologically diverse group of pelagic photoautotrophs that share common metabolic functions but not evolutionary histories. In contrast to terrestrial plants, a major schism occurred in the evolution of the eukaryotic phytoplankton that gave rise to two major plastid superfamilies. The green superfamily appropriated chlorophyll b, whereas the red superfamily uses chlorophyll c as an accessory photosynthetic pigment. Fossil evidence suggests that the green superfamily dominated Palaeozoic oceans. However, after the end-Permian extinction, members of the red superfamily rose to ecological prominence. The processes responsible for this shift are obscure. Here we present an analysis of major nutrients and trace elements in 15 species of marine phytoplankton from the two superfamilies. Our results indicate that there are systematic phylogenetic differences in the two plastid types where macronutrient (carbon:nitrogen:phosphorus) stoichiometries primarily reflect ancestral pre-symbiotic host cell phenotypes, but trace element composition reflects differences in the acquired plastids. The compositional differences between the two plastid superfamilies suggest that changes in ocean redox state strongly influenced the evolution and selection of eukaryotic phytoplankton since the Proterozoic era.

Topics: Biological Evolution; Chlorophyll; Eukaryotic Cells; Genome, Plant; Oceans and Seas; Oxidation-Reduction; Photosynthesis; Phylogeny; Phytoplankton; Plastids; Symbiosis; Time Factors; Trace Elements

Room-temperature absorption spectra of H. akashiwo cells under iron limitation showed a chlorophyll c absorption peak at 630 nm, 2 nm blue-shifted from its normal position of 632 nm. Moreover, because of the increase in the relative carotenoid abundance compared to Chl a, there was an extra shoulder peak at 480 nm for the iron-limited cells. Their fluorescence spectra (77 K) have one prominent chlorophyll emission peak at 685 nm. By comparison with Fe-replete cells (10 mumol.L-1), the fluorescence yield from 685 nm band increased by about 2 times in Fe deplete cells (5 nmol.L-1), and about 1.4 times in low iron cells (100 nmol.L-1), respectively. 48 h after Fe addition, the height of 685 nm peak was considerably decreased from that observed in low iron (100 nmol.L-1) and iron deficient (ID) cells before Fe addition, which indicated that there was a significantly higher energy dissipation, and thus, a less effective photosynthesis under the lack of Fe.

Topics: Chlorophyll; Eukaryota; Harmful Algal Bloom; Iron; Spectrometry, Fluorescence; Spectrum Analysis

Chlorophyll (Chl)-containing light-harvesting complexes (LHCs) in chloroplasts of plant and algal cells usually include an oxidized Chl (Chl b or c) in addition to Chl a. Oxidation of peripheral groups on the tetrapyrrole structure increases the Lewis acid strength of the central Mg atom. We propose that the resulting stronger coordination bonds between oxidized Chls and ligands in LHC apoproteins (LHCPs) stabilize the initial intermediates and thus promote assembly of LHCs within the chloroplast envelope.

Topics: Acids; Algal Proteins; Amino Acid Motifs; Animals; Biological Transport; Chlamydomonas; Chlorophyll; Chlorophyll Binding Proteins; Chloroplasts; Magnesium; Plant Proteins

In order to obtain information on the organization of the pigment molecules in chlorophyll (Chl) a/b/c-containing organisms, we have carried out circular dichroism (CD), linear dichroism (LD) and absorption spectroscopic measurements on intact cells, isolated thylakoids and purified light-harvesting complexes (LHCs) of the prasinophycean alga Mantoniella squamata. The CD spectra of the intact cells and isolated thylakoids were predominated by the excitonic bands of the Chl a/b/c LHC. However, some anomalous bands indicated the existence of chiral macrodomains, which could be correlated with the multilayered membrane system in the intact cells. In the red, the thylakoid membranes and the LHC exhibited a well-discernible CD band originating from Chl c, but otherwise the CD spectra were similar to that of non-aggregated LHC II, the main Chl a/b LHC in higher plants. In the Soret region, however, an unusually intense (+) 441 nm band was observed, which was accompanied by negative bands between 465 and 510 nm. It is proposed that these bands originate from intense excitonic interactions between Chl a and carotenoid molecules. LD measurements revealed that the Q(Y) dipoles of Chl a in Mantoniella thylakoids are preferentially oriented in the plane of the membrane, with orientation angles tilting out more at shorter than at longer wavelengths (9 degrees at 677 nm, 20 degrees at 670 nm and 26 degrees at 662 nm); the Q(Y) dipole of Chl c was found to be oriented at 29 degrees with respect to the membrane plane. These data and the LD spectrum of the LHC, apart from the presence of Chl c, suggest an orientation pattern of dipoles similar to those of higher plant thylakoids and LHC II. However, the tendency of the Q(Y) dipoles of Chl b to lie preferentially in the plane of the membrane (23 degrees at 653 nm and 30 degrees at 646 nm) is markedly different from the orientation pattern in higher plant membranes and LHC II. Hence, our CD and LD data show that the molecular organization of the Chl a/b/c LHC, despite evident similarities, differs significantly from that of LHC II.

Topics: Bacterial Proteins; Chlorophyll; Chlorophyll A; Circular Dichroism; Eukaryota; Light-Harvesting Protein Complexes; Photosynthetic Reaction Center Complex Proteins; Pigments, Biological; Spectrum Analysis; Thylakoids

Resonance Raman spectroscopy of an antenna protein from the brown alga Laminaria saccharina has been used to investigate the molecular structure of this light-harvesting complex (LHC) at the level of its bound pigments, chlorophylls (chl) a and c and the xanthophyll fucoxanthin. Evidence has been obtained for the conservation of pigment structure during the isolation procedure used. Six chl a and two chl c molecules are indicated from the positions and relative contributions of stretching modes of their keto-carbonyl groups. Of special interest is the presence of a population of chls a having a protein-binding conformation highly similar to that seen in antenna proteins from higher plants, possibly indicating a common structural motif within this extended gene family. The eight fucoxanthin molecules evidenced are all in the all-trans conformation; however, one or two have a highly twisted configuration. The results are discussed in terms of common and varying structural features of LHCs in higher plants and algae.

Topics: Binding Sites; Carotenoids; Chlorophyll; Chlorophyll A; Laminaria; Light-Harvesting Protein Complexes; Molecular Conformation; Photosynthetic Reaction Center Complex Proteins; Protein Conformation; Spectrum Analysis, Raman; Xanthophylls

A fucoxanthin-chlorophyll protein (FCP) cDNA from the raphidophyte Heterosigma carterae encodes a 210-amino acid polypeptide that has similarity to other FCPs and to the chlorophyll a/b-binding proteins (CABs) of terrestrial plants and green algae. The putative transit sequence has characteristics that resemble a signal sequence. The Heterosigma fcp genes are part of a large multigene family which includes members encoding at least two significantly different polypeptides (Fcp1, Fcp2). Comparison of the FCP sequences to the recently determined three-dimensional structure of the pea LHC II complex indicates that many of the key amino acids thought to participate in the binding of chlorophyll and the formation of complex-stabilizing ionic interactions are well conserved. Phylogenetic analyses of sequences of light-harvesting proteins shows that the FCPs of several chromophyte phyla form a natural group separate from the intrinisic peridinin-chlorophyll proteins (iPCPs) of the dinoflagellates: Although the FCP and CAB genes shared a common ancestor, these lineages diverged from each other prior to the separation of the CAB LHC I and LHC II sequences in the green algae and terrestrial plants.

Topics: Amino Acid Sequence; Carotenoids; Chlorophyll; Chlorophyll A; DNA, Complementary; Eukaryota; Evolution, Molecular; Light-Harvesting Protein Complexes; Models, Molecular; Molecular Sequence Data; Photosynthetic Reaction Center Complex Proteins; Phylogeny; Protein Conformation; Sequence Homology, Amino Acid; Xanthophylls

We investigated the primary structure of a cDNA encoding a light-harvesting protein from the marine chrysophyte Isochrysis galbana. Antibodies raised against the major fucoxanthin, chlorophyll a/c-binding light-harvesting protein (FCP) of I. galbana were used to select a cDNA clone encoding one of the FCP apoproteins. The nucleic acid and deduced amino acid sequences reveal conserved regions within the first and third transmembrane spans with Chl a/b-binding proteins and with FCPs of another chromophyte. However, the amino acid identity between I. galbana FCP and other cab genes of FCPs is only ca. 30%. Phylogenetic analyses demonstrated that the FCP genes of both diatoms and chrysophytes sequenced to date are more closely related to cab genes encoding LHC I, CP 29, and CP 24 of higher plants than to cab genes encoding LHC II of chlorophytes. We propose that LHC I, CP 24 and CP 29 and FCP might have originated from a common ancestral chl binding protein and that the major LHC II of Chl a/b-containing organisms arose after the divergence between the chromophytes and the chlorophytes.

Topics: Amino Acid Sequence; Apoproteins; Biological Evolution; Carotenoids; Chlorophyll; Chlorophyll A; Cross Reactions; Eukaryota; Genes, Plant; Light-Harvesting Protein Complexes; Molecular Sequence Data; Multigene Family; Photosynthetic Reaction Center Complex Proteins; Sequence Homology, Amino Acid; Xanthophylls

The gene for ribosomal protein L27 (rpl27) has not been found in plastid genomes. We report here that the rpl27 gene is located in the plastid genome of the prymnesiophyte Pleurochrysis carterae. The deduced amino acid sequence showed 59% identity with E. coli L27. 1.0 kb transcript of the gene was detected by Northern blot analysis. Nucleotide sequence analysis of PCR products suggested that rpl27 is widespread in the genomes of Prymesiophyta and Rhodophyta. In all species of Prymnesiophyta examined in this study, the gene is located at the 3' downstream region of Rubisco operon.

Topics: Amino Acid Sequence; Base Sequence; Blotting, Northern; Cell Nucleus; Chlorophyll; DNA; Eukaryota; Molecular Sequence Data; Plastids; Ribosomal Proteins; Sequence Homology, Amino Acid

The N-terminus of the major polypeptide component of the light-harvesting complex (LHC) from the brown alga Laminaria saccharina is blocked. Two partial sequences, one near the N-terminus and the other near the C-terminus, have been obtained by chemical cleavage with acetic acid and N-chlorosuccinimide. Four peptides were separated after trypsin digestion of the thylakoid membranes. One fragment is not phosphorylated, is not blocked, and has been sequenced. Purification on a reversed-phase column showed two forms of the LHC protein: the more hydrophobic form appears to be bound to photosystem I. These results are compared with LHC from other Chromophytes and the CAB family of green plants.

Topics: Amino Acid Sequence; Aspartic Acid; Carotenoids; Chlorophyll; Chlorophyll A; Chloroplasts; Intracellular Membranes; Laminaria; Light-Harvesting Protein Complexes; Molecular Sequence Data; Peptide Fragments; Phosphorylation; Photosynthetic Reaction Center Complex Proteins; Photosystem I Protein Complex; Proline; Sequence Analysis; Succinimides; Trypsin; Xanthophylls

Compared with the carbon-13 isotopic composition of the ubiquitous C32DPEP (DPEP, deoxophylloerythroetioporphyrin) the heavy but equivalent carbon-13 isotopic composition for the porphyrin structures 15(2)-methyl-15,17-ethano-17-nor-H-C30DPEP and 15,17-butano-, 13,15-ethano-13(2),17-propano-, and 13(1)-methyl-13,15-ethano-13(2),17-propanoporphyrin suggests a common precursor, presumably chlorophyll c, for these petroporphyrins isolated from the marine Julia Creek oil shale and the lacustrine Condor oil shale. Similarly, the heavy but variable carbon-13 isotopic composition of 7-nor-H-C31DPEP compared with C32DPEP is consistent with an origin from both chlorophyll b and chlorophyll c3. The equivalent carbon-13 isotopic composition for 13(2)-methyl-C33DPEP compared with C32DPEP suggests a common origin resulting from a weighted average of chlorophyll inputs.

Topics: Australia; Carbon; Carbon Radioisotopes; Chlorophyll; Geologic Sediments; Oceans and Seas; Petroleum; Porphyrins

A 0.8 kb AvaI/SmaI fragment of the plastid genome of the chlorophyll c-containing alga Cryptomonas phi encompassing the rRNA spacer region and flanking genes has been cloned and sequenced. The spacer region between the 16S and 23S rRNA genes is 275 base pairs long, one of the shortest yet reported, and it contains uninterrupted genes for tRNA(Ile) and tRNA(Ala) separated by only two base pairs. The coding regions for tRNAs and rRNAs have been compared with those from cyanobacteria, land plants and other algae and the possible evolutionary relationships discussed.

Topics: Base Sequence; Chlorophyll; Cloning, Molecular; DNA, Ribosomal; Eukaryota; Molecular Sequence Data; Nucleic Acid Conformation; Restriction Mapping; RNA, Ribosomal, 16S; RNA, Transfer; Sequence Homology, Nucleic Acid

Topics: Amino Acid Sequence; Base Sequence; Chlorophyll; Eukaryota; Genes; Molecular Sequence Data; Ribosomal Proteins; RNA, Transfer, Amino Acid-Specific; RNA, Transfer, Arg

The gene for the small subunit of ribulose-1,5-bisphosphate carboxylase (Rubisco) is located in the large single-copy region of the plastid genome of the chlorophyll c-containing alga Cryptomonas phi. The coding sequence is 417 base pairs long, encoding a protein of 139 amino acids, considerably longer than most other small subunit proteins. It is found 83 base pairs downstream from the gene for the large subunit and is cotranscribed with it. An 18 base pair perfect inverted repeat is located 8 base pairs beyond the termination codon. Sequence analysis shows the gene to be more closely related to cyanobacterial and cyanelle small-subunit genes than to those of green algae or land plants. This is the first reported sequence of a Rubisco small-subunit gene which is plastid-encoded and it exhibits a number of unique features. The derived amino acid sequence shows extensive similarity to a partial amino acid sequence from a brown alga, indicating that this gene will be of major interest as a probe for the small subunit genes in other algae and for determining possible evolutionary ancestors of algal plastids.

Topics: Amino Acid Sequence; Animals; Base Sequence; Biological Evolution; Chlorophyll; Eukaryota; Genes, Plant; Macromolecular Substances; Molecular Sequence Data; Plants; Restriction Mapping; Ribulose-Bisphosphate Carboxylase; Sequence Homology, Amino Acid

Topics: Chlorophyll; Research; Spectrum Analysis

Topics: Chlorophyll; Sargassum; Seaweed

Topics: Chlorophyll