Terpenoid synthases

In pepper as in many plants, there are two sources of isoprene monomers the mevalonic acid pathway and the plastidal pool from pymvate and glyceraldehyde-3-phosphate [26], Pepper carotenoid biosynthesis uses the plastidal pathway for the isopentyl pyrophosphate monomers and the resident terpenoid synthases and transferases [27], Using the 5-carbon isoprene pool, the prenyl transferases sequentially... 

Aubourg S, Lechamy A, Bohlmann J (2002) Genomic analysis of the terpenoid synthase (AtTPS) gene famUy of Arabidopsis thaliana. Mol Genet Genomics 267 730-745... 

Much attention has been paid to the last step of the formation of monoter-penes and sesquiterpenes, which is catalysed by terpenoid synthases. Over 30 complementary DNAs (cDNAs) encoding plant terpenoid synthases involved in the primary and secondary metabolism have been cloned, characterised, and the proteins heterologously expressed [6]. However, because geranyl diphosphate and farnesyl diphosphate are not readily available substrates, their biotransformation by terpenoid synthases is not economically viable. As a result, considerable effort has been put into engineering the total plant terpenoid biosynthetic pathway in recombinant microorganisms. 

Bohlmann, J., Meyer-Gauen, G. and Croteau, R. (1998). Plant terpenoid synthases ... 

Bohlmann J., Meyer-Gauen G. and Croteau R. (1998) Plant terpenoid synthases molecular biology and phylogenetic analysis. Proc. Natl. Acad. Sci. USA 95, 4126-4133. Boppre M. (1984) Chemically mediated interactions between butterflies. In The Biology of Butterflies, eds R. I. Vane-Wright and P. R. Ackery, pp. 259-275. Princeton University Press, Princeton, NJ. 

AUBOURG, S., LECHARNY, A., BOHLMANN, J., Genomic analysis of the terpenoid synthase AtTPS gene family of Arabidopsis thaliana., Mol. Gen. Genom., 2002,267,730-745. 

To date over 30 plant terpenoid synthases have been cloned as cDNAs, and many of these were found to encode enzymes of secondary metabolism (43). Isolation and analysis of six genomic clones encoding monoterpene ((—)-pinene and (—)-limonene), sesquiterpene ((E)-a-bisabolene and S-selinene) and diterpene (abietadiene) synthases from Abies grandis, and a diterpene (taxadiene) synthase from Taxus brevifolia have been reported (44). Overexpression of a cotton farnesyl diphosphate synthase (EPPS) in transgenic Artemesia annua has resulted in 3- to 4-fold increase in the yield of the sesquiterpenoid anti-malarial drug, artemisinin, in hairy roots (45). 

Bohlmann J, Meyer-Gaven G, Croteau R. Plant terpenoid synthases molecular biology and phylogenetic analysis. Proc. Natl. Acad. Sci. USA. 1998 95 4126-4133. 

Picaud et al. purified recombinant AMDS and determined its pH optimum to 6.5 [24]. Several sesquiterpene synthases show maximum activity in this range examples are tobacco 5-epz-aristolochene synthase [25,26], germa-crene A synthase from chickory [26] and nerolidol synthase from maize [27]. Terpenoid synthases are, however, not restricted to a pH optimum in this range. Intriguing examples are the two (-l-)-(5-cadinene synthase variants from cotton, which exhibit maximum activity at pH 8.7 and 7-7.5, respectively [28] and 8-epi-cedrol synthase from A. annua [29] with the pH optimum around... 

MILLER, B., MADILAO, L.L., RALPH, S., BOHLMANN, J., Insect-induced conifer defense. White pine weevil and methyl jasmonate induce traumatic resinosis, de novo formed volatile emissions, and accumulation of terpenoid synthase and octadecanoid pathway transcripts in Sitka spruce. Plant Physiol, 2005, 137, 369-382. 

BOHLMANN, J., MEYER-GAUEN, G., CROTEAU, R., Plant terpenoid synthases Molecular biology and phylogenetic analysis, Proc. Natl Acad. ScL USA, 1998, 95, 4126-4133. 

Fig. 6.7 A case of moonlighting. The S. coelicolor CYP170A1 converts epi-isozizaene via albaflavenol intermediate(s) to the sesquiterpene single ketone antibiotic albaflavenone by two successive allylic oxidations (a) [202], A secondary terpenoid synthase role was also discovered to produce farnesene (b) [849]. The structure...

Bohhnann J, Meyer-Gauen G, Croteau R (1998) Plant terpenoid synthases molecular biology and phylogenetic analysis. Proc Natl Acad Sci USA 95 4126-4133 Sacchettini JC, Poulter CD (1997) Creating isoprenoid diversity. Science 277 1788-1789 Dereth RP, Jeanne MR, Bonnie B, Seiichi PTM (2006) Biosynthetic diversity in plant triterpene cyclization. Curr Opin Plant Biol 9 305-314... 

Despite great diversity in form and function, the terpenoids are unified in their common biosynthetic origin. The biosynthesis of all terpenoids from simple, primary metabolites can be divided into four overall steps (a) synthesis of the fundamental precursor IPP (b) repetitive additions of IPP to form a series of prenyl diphosphate homologs, which serve as the immediate precursors of the different classes of terpenoids (c) elaboration of these allylic prenyl diphosphates by specific terpenoid synthases to yield terpenoid skeletons and (d) secondary enzymatic modifications to the skeletons (largely redox reactions) to give rise to the functional properties and great chemical diversity of this family of natural products. As bacosides are triterpenoid derivatives, they may probably foUow the common biosynthetic pathway of terpenoid production [40]. 

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