Recent Advances Regarding Diterpene Cyclase Genes in Higher Plants and Fungi

Abstract

Cyclic diterpenoids are commonly biosynthesized from geranylgeranyl diphosphate (GGDP) through the formation of carbon skeletons by specific cyclases and subsequent chemical modifications, such as oxidation, reduction, methylation, and glucosidation. A variety of diterpenoids are produced in higher plants and fungi. Rice produces four classes of diterpene phytoalexins, phytocassanes A to E, oryzalexins A to F, oryzalexin S, and momilactones A and B. The six diterpene cyclase genes involved in the biosynthesis of these phytoalexins were identified and characterized. Fusicoccin A was produced by the phytopathogenic Phomopsis amygdali and served as a plant H þ -ATPase activator. A PaFS, encoding a fungal diterpene synthase responsible for fusicoccin biosynthesis, was isolated. The PaFS is an unusual chimeric diterpene synthase that possesses not only terpene cyclase activity (the formation of fusicoccadiene, a biosynthetic precursor of fusicoccin A), but also prenyltransferase activity (the formation of GGDP). Thus, we identified a unique multifunctional diterpene synthase family in fungi.

Identity, regulation, and activity of inducible diterpenoid phytoalexins in maize

“…In cotton (Gossypium hirsutum), pathogens and insect herbivores trigger synthesis of the sesquiterpene δ-cadinene and numerous subsequent oxidation products, which, collectively, afford protection against these attackers (2,3). Similarly, in rice (Oryza sativa), pathogen infection induces the levels of transcripts encoding key biosynthetic enzymes, namely, an ent-copalyl diphosphate synthase (ent-CPS; OsCPS2) and a syn-CPS (OsCPS4), which lead to diterpenoid phytoalexin production (4). These inducible diterpenoids have established roles in protecting against the ascomycete fungus Magnaporthe grisea, the causal agent of rice blast disease, which is responsible for 10-30% of losses in production (5).…”

CYP701A8: A Rice ent-Kaurene Oxidase Paralog Diverted to More Specialized Diterpenoid Metabolism

“…Rice (Oryza sativa) produces more than 20 labdanerelated diterpenoids that act as antimicrobial phytoalexins (Peters, 2006;Toyomasu, 2008). Sequencing of the rice genome demonstrated the presence of multiple CPS, KS(L), and KO family members (IRGSP, 2005), although only one of each is involved in GA biosynthesis .…”

“…Biochemical characterization of the rice CPS and KS(L) families has revealed the expected functional divergence-i.e. as necessary for the known production of alternative labdanerelated diterpenoids (Peters, 2006;Toyomasu, 2008). However, these diterpene synthases produce olefins that require further elaboration, particularly the insertion of oxygen by CYP (Kato et al, 1995), to form bioactive phytoalexins (Peters, 2006).…”

Unique Biosynthesis of Sesquarterpenes (C35Terpenes)

“…31) It has been reported that many terpene cyclases have broad substrate specificities, and that other classes of terpenes have been created in vitro. [2][3][4][5][6][7][8][9][10][11][12][13][14][15] A combination of studies identifying enzymatic products biosynthesized from unusual substrates and the analysis of genome sequences should lead not only to the discovery of additional functions of these enzymes in the organism, but also to the identification of novel natural terpenoids that have functions in their producers.…”

“…[1][2][3][4][5][6][7][8][9][10][11][12][13][14][15] These compounds including hormones, vitamins, drugs, flavorings, and pigments, are categorized by number of C 5 isoprene units, as follows: hemi-(C 5 ), 1 unit; mono-(C 10 ), 2 units; sesqui-(C 15 ), 3 units; di-(C 20 ), 4 units; sester-(C 25 ), 5 units; tri-(C 30 ), 6 units; and tetraterpenes (C 40 ), 8 units. [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15] In contrast, little is known about C 35 terpenes. To the best of my knowledge, only 19 cyclic and eight linear C 35 terpenes have been identified to date, [16][17][18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33]…”