geranyl-pyrophosphate and linalool

Topics: Acyclic Monoterpenes; Bacterial Proteins; Biosynthetic Pathways; Diphosphates; Diterpenes; Escherichia coli; Gene Expression Regulation, Bacterial; Hydro-Lyases; Metabolic Engineering; Streptomyces

In order to improve the availability of geranyl diphosphate (GPP) in the mevalonate pathway for enhancing (S)-linalool production in Saccharomyces cerevisiae.. A (S)-linalool synthase (LIS): AaLS1 from Actinidia arguta was coexpressed with FPPS with different peptide linkers to redirect the flux from geranyl diphosphate (GPP) to (S)-linalool production in S. cerevisiae. The strain with the best peptide linker ((GGGGS)3 ), produced 101·55 ± 2·97 μg l(-1) (S)-linalool, a 69·7% increase compared to those with two independent LIS and FPPS expressed. In a 3-l fermenter, the (S)-linalool titre was further improved to 240·64 ± 5·31 μg l(-1) .. The results demonstrate that the fusion proteins catalysing consecutive steps in a metabolic pathway significantly improved the (S)-linalool production with GPP as precursor.. The fusion protein strategy co-expressing AaLS1 and FPPS, assembled with a long peptide linker made S. cerevisiae produced the highest reported (S)-Linalool titre to date.

Topics: Actinidia; Acyclic Monoterpenes; Diphosphates; Diterpenes; Gene Expression; Geranyltranstransferase; Hydro-Lyases; Metabolic Networks and Pathways; Monoterpenes; Plant Proteins; Recombinant Fusion Proteins; Saccharomyces cerevisiae; Saccharomyces cerevisiae Proteins

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

S-Linalool is one of the volatiles emitted by Clarkia breweri Grey [Green] flowers to attract its moth pollinator. S-Linalool synthase, the enzyme that stereoselectively converts the ubiquitous C10 intermediate GPP to S-linalool, is abundant in stigmata of freshly opened flowers, and it was purified to > 95% homogeneity by anion-exchange and hydroxyapatite chromatography. S-Linalool synthase is operationally soluble as are other monoterpene synthases, has a Km of 0.9 microM for geranyl pyrophosphate, exhibits a strict requirement for a divalent metal cofactor with a preference for Mn2+ (Km = 45 microM), and shows an optimal pH of 7.4. The enzyme is active as a monomer of 76 +/- 3 kDa as determined by gel permeation chromatography and polyacrylamide gel electrophoresis. Neither S- nor R-linalyl pyrophosphates are substrates for the C. breweri S-linalool synthase, although this tertiary allylic pyrophosphate ester is a bound intermediate in the biosynthesis of cyclic monoterpenes from geranyl pyrophosphate in many plant species, where it also serves as an alternate substrate.

Topics: Acyclic Monoterpenes; Hydro-Lyases; Monoterpenes; Odorants; Plant Shoots; Polyisoprenyl Phosphates; Stereoisomerism; Substrate Specificity; Terpenes