farnesyl-pyrophosphate and nerolidol

In metabolic engineering, loss-of-function experiments are used to understand and optimise metabolism. A conditional gene inactivation tool is required when gene deletion is lethal or detrimental to growth. Here, we exploit auxin-inducible protein degradation as a metabolic engineering approach in yeast. We demonstrate its effectiveness using terpenoid production. First, we target an essential prenyl-pyrophosphate metabolism protein, farnesyl pyrophosphate synthase (Erg20p). Degradation successfully redirects metabolic flux toward monoterpene (C10) production. Second, depleting hexokinase-2, a key protein in glucose signalling transduction, lifts glucose repression and boosts production of sesquiterpene (C15) nerolidol to 3.5 g L

Topics: Bacterial Proteins; Cell Cycle Checkpoints; Coenzyme A Ligases; Glucose; Hexokinase; Indoleacetic Acids; Limonene; Metabolic Engineering; Metabolic Flux Analysis; Polyisoprenyl Phosphates; Proteolysis; Saccharomyces cerevisiae; Saccharomyces cerevisiae Proteins; Sesquiterpenes; Terpenes

Sesquiterpenes are C15 isoprenoids with utility as fragrances, flavours, pharmaceuticals, and potential biofuels. Microbial fermentation is being examined as a competitive approach for bulk production of these compounds. Competition for carbon allocation between synthesis of endogenous sterols and production of the introduced sesquiterpene limits yields. Achieving balance between endogenous sterols and heterologous sesquiterpenes is therefore required to achieve economical yields. In the current study, the yeast Saccharomyces cerevisiae was used to produce the acyclic sesquiterpene alcohol, trans-nerolidol. Nerolidol production was first improved by enhancing the upstream mevalonate pathway for the synthesis of the precursor farnesyl pyrophosphate (FPP). However, excess FPP was partially directed towards squalene by squalene synthase (Erg9p), resulting in squalene accumulation to 1% biomass; moreover, the specific growth rate declined. In order to re-direct carbon away from sterol production and towards the desired heterologous sesquiterpene, a novel protein destabilisation approach was developed for Erg9p. It was shown that Erg9p is located on endoplasmic reticulum and lipid droplets through a C-terminal ER-targeted transmembrane peptide. A PEST (rich in Pro, Glu/Asp, Ser, and Thr) sequence-dependent endoplasmic reticulum-associated protein degradation (ERAD) mechanism was established to decrease cellular levels of Erg9p without relying on inducers, repressors or specific repressing conditions. This improved nerolidol titre by 86% to ~100mgL

Topics: Biosynthetic Pathways; Enzyme Activation; Farnesyl-Diphosphate Farnesyltransferase; Genetic Enhancement; Metabolic Engineering; Metabolic Networks and Pathways; Polyisoprenyl Phosphates; Saccharomyces cerevisiae; Saccharomyces cerevisiae Proteins; Sesquiterpenes

The purpose of this work was to characterize the functions of two sesquiterpene synthase genes from moso bamboo (Phyllostachys edulis). Two novel sesquiterpene synthase genes, belonging to the Tpsa subfamily, were isolated from moso bamboo. MoTPS2 was 1641 bp in length and encoded a protein of 63 kDa, whereas MoTPS6 was 1626 bp in length, encoded protein 62.4 kDa. Both genes were expressed in Pichia pastoris for heterologous expression, and protein contents reached 0.243 μg μL(-1) for MoTPS2 and 0.088 μg μL(-1) for MoTPS6. The soluble enzymes were catalytically active, and capable of converting farnesyl pyrophosphate to two distinct sesquiterpene compounds. The MoTPS2 gene encoded a farnesol synthase which was responsible for the production of (E, E)-farnesol. MoTPS6 showed nerolidol synthase activity, catalyzing the formation of (E)-nerolidol. Functional characterization of both MoTPSs should prove beneficial for future research into large-scale fermentation of sesquiterpenes.

Topics: Amino Acid Sequence; Cloning, Molecular; Farnesol; Gene Expression Regulation, Plant; Ligases; Molecular Sequence Data; Phylogeny; Pichia; Plant Proteins; Poaceae; Polyisoprenyl Phosphates; Recombinant Proteins; Sequence Alignment; Sesquiterpenes

Flowers of the kiwifruit species Actinidia chinensis produce a mixture of sesquiterpenes derived from farnesyl diphosphate (FDP) and monoterpenes derived from geranyl diphosphate (GDP). The tertiary sesquiterpene alcohol (E)-nerolidol was the major emitted volatile detected by headspace analysis. Contrastingly, in solvent extracts of the flowers, unusually high amounts of (E,E)-farnesol were observed, as well as lesser amounts of (E)-nerolidol, various farnesol and farnesal isomers, and linalool. Using a genomics-based approach, a single gene (AcNES1) was identified in an A. chinensis expressed sequence tag library that had significant homology to known floral terpene synthase enzymes. In vitro characterization of recombinant AcNES1 revealed it was an enzyme that could catalyse the conversion of FDP and GDP to the respective (E)-nerolidol and linalool terpene alcohols. Enantiomeric analysis of both AcNES1 products in vitro and floral terpenes in planta showed that (S)-(E)-nerolidol was the predominant enantiomer. Real-time PCR analysis indicated peak expression of AcNES1 correlated with peak (E)-nerolidol, but not linalool accumulation in flowers. This result, together with subcellular protein localization to the cytoplasm, indicated that AcNES1 was acting as a (S)-(E)-nerolidol synthase in A. chinensis flowers. The synthesis of high (E,E)-farnesol levels appears to compete for the available pool of FDP utilized by AcNES1 for sesquiterpene biosynthesis and hence strongly influences the accumulation and emission of (E)-nerolidol in A. chinensis flowers.

Topics: Actinidia; Acyclic Monoterpenes; Alkyl and Aryl Transferases; Arabidopsis; Base Sequence; Diphosphates; Diterpenes; Farnesol; Flowers; Gene Expression Regulation, Plant; Kinetics; Molecular Sequence Data; Monoterpenes; Nicotiana; Oils, Volatile; Phylogeny; Plant Leaves; Plant Proteins; Polyisoprenyl Phosphates; Recombinant Proteins; Sequence Analysis, DNA; Sesquiterpenes; Substrate Specificity

Volatile components, such as terpenoids, are emitted from aerial parts of plants and play a major role in the interaction between plants and their environment. Analysis of the composition and emission pattern of volatiles in the model plant Arabidopsis showed that a range of volatile components are released, primarily from flowers. Most of the volatiles detected were monoterpenes and sesquiterpenes, which in contrast to other volatiles showed a diurnal emission pattern. The active terpenoid metabolism in wild-type Arabidopsis provoked us to conduct an additional set of experiments in which transgenic Arabidopsis overexpressing two different terpene synthases were generated. Leaves of transgenic plants constitutively expressing a dual linalool/nerolidol synthase in the plastids (FaNES1) produced linalool and its glycosylated and hydroxylated derivatives. The sum of glycosylated components was in some of the transgenic lines up to 40- to 60-fold higher than the sum of the corresponding free alcohols. Surprisingly, we also detected the production and emission of nerolidol, albeit at a low level, suggesting that a small pool of its precursor farnesyl diphosphate is present in the plastids. Transgenic lines with strong transgene expression showed growth retardation, possibly as a result of the depletion of isoprenoid precursors in the plastids. In dual-choice assays with Myzus persicae, the FaNES1-expressing lines significantly repelled the aphids. Overexpression of a typical cytosolic sesquiterpene synthase resulted in the production of only trace amounts of the expected sesquiterpene, suggesting tight control of the cytosolic pool of farnesyl diphosphate, the precursor for sesquiterpenoid biosynthesis. This study further demonstrates the value of Arabidopsis for studies of the biosynthesis and ecological role of terpenoids and provides new insights into their metabolism in wild-type and transgenic plants.

Topics: Acyclic Monoterpenes; Alkyl and Aryl Transferases; Animals; Aphids; Arabidopsis; Chloroplasts; Cichorium intybus; Gene Expression Regulation, Plant; Glycosylation; Hydroxylation; Monoterpenes; Plant Proteins; Plants, Genetically Modified; Polyisoprenyl Phosphates; Sesquiterpenes; Sesquiterpenes, Germacrane; Terpenes; Volatilization

Upon herbivore attack, maize (Zea mays L.) emits a mixture of volatile compounds that attracts herbivore enemies to the plant. One of the major components of this mixture is an unusual acyclic C11 homoterpene, (3E)-4,8-dimethyl-1,3,7-nonatriene (DMNT), which is also emitted by many other species following herbivore damage. Biosynthesis of DMNT has been previously shown to proceed via the sesquiterpene alcohol, (E)-nerolidol. Here we demonstrate an enzyme activity that converts farnesyl diphosphate, the universal precursor of sesquiterpenes, to (3S)-(E)-nerolidol in cell-free extracts of maize leaves that had been fed upon by Spodoptera littoralis. The properties of this (E)-nerolidol synthase resemble those of other terpene synthases. Evidence for its participation in DMNT biosynthesis includes the direct incorporation of deuterium-labeled (E)-nerolidol into DMNT and the close correlation between increases in (E)-nerolidol synthase activity and DMNT emission after herbivore damage. Since farnesyl diphosphate has many other metabolic fates, (E)-nerolidol synthase may represent the first committed step of DMNT biosynthesis in maize. However, the formation of this unusual acyclic terpenoid appears to be regulated at both the level of (E)-nerolidol synthase and at later steps in the pathway.

Topics: Alkyl and Aryl Transferases; Animals; Carbon-Carbon Lyases; Chromatography, Gas; Enzyme Induction; Gas Chromatography-Mass Spectrometry; Plant Leaves; Polyisoprenyl Phosphates; Sesquiterpenes; Spodoptera; Stereoisomerism; Terpenes; Zea mays

Many plant species respond to herbivory with de novo production of a mixture of volatiles that attracts carnivorous enemies of the herbivores. One of the major components in the blend of volatiles produced by many different plant species in response to herbivory by insects and spider mites is the homoterpene 4,8-dimethyl-1,3(E), 7-nonatriene. One study (J. Donath, W. Boland [1995] Phytochemistry 39: 785-790) demonstrated that a number of plant species can convert the acyclic sesquiterpene alcohol (3S)-(E)-nerolidol to this homoterpene. Cucumber (Cucumis sativus L.) and lima bean (Phaseolus lunatus L.) both produce 4,8-dimethyl-1,3(E),7-nonatriene in response to herbivory. We report the presence in cucumber and lima bean of a sesquiterpene synthase catalyzing the formation of (3S)-(E)-nerolidol from farnesyl diphosphate. The enzyme is inactive in uninfested cucumber leaves, slightly active in uninfested lima bean leaves, and strongly induced by feeding of the two-spotted spider mite (Tetranychus urticae Koch) on both plant species, but not by mechanical wounding. The activities of the (3S)-(E)-nerolidol synthase correlated well with the levels of release of 4, 8-dimethyl-1,3(E),7-nonatriene from the leaves of the different treatments. Thus, (3S)-(E)-nerolidol synthase is a good candidate for a regulatory role in the release of the important signaling molecule 4,8-dimethyl-1,3(E),7-nonatriene.

Topics: Air; Animals; Carbon-Carbon Lyases; Cucumis sativus; Eating; Enzyme Induction; Fabaceae; Kinetics; Mites; Models, Chemical; Oils, Volatile; Phosphoric Monoester Hydrolases; Physical Stimulation; Plant Leaves; Plants, Medicinal; Polyisoprenyl Phosphates; Sesquiterpenes; Signal Transduction; Terpenes