Sesquiterpene cyclases

Volicifin has also been shown to activate a specific maize sesquiterpene cyclase gene, stcl, which is also activated in response to caterpillar feeding or regurgitant treatment (Shen et al., 2000). The transcription of stcl results in the production of a naphthalene-based sesquiterpenoid, which we have not yet detected from the many maize lines we have studied (e.g., Gouinguene etal., 2001). It would be interesting to see if this volicitin-induced substance shows attractiveness to natural enemies of the caterpillars that induce its production. 

Shen, B Zheng, Z. P. and Dooner, H. K. (2000). A maize sesquiterpene cyclase gene induced by insect herbivory and volicitin. Characterization of wild-type and mutant alleles. Proceedings of the National Academy of Sciences, USA 97 14807-14812. 

SESQUITERPENE CYCLASES CATALYZE COMPLEX REACTIONS CREATING AN LARGE ARRAY OF CHEMICAL SCAFFOLDS... 

VOGELI, U., CHAPPELL, J., Induction of sesquiterpene cyclase and suppression of squalene synthetase activities in plant cell cultures treated with fungal elicitor, Plant Physiol., 1988, 88, 1291-1296. 

FACCHINI, P.J., CHAPPELL, J., A gene family for an elicitor-induced sesquiterpene cyclase in tobacco, Proc. Natl. Acad. Sci. USA, 1992, 89, 11088-11092. 

YIN, S., MEI, L., NEWMAN, J., BACK, K., CHAPPELL, J., Regulation of sesquiterpene cyclase gene expression characterization of an elicitor and pathogen inducible promoter, Plant Physiol, 1997,115,437-451. 

In Gossypium spp. (Malvaceae), sesquiterpenoid phytoalexins identified so far are cadinene derivatives that are biosynthesized from -cadinene.241 CAD1-A and CAD1-C were functionally identified as sesquiterpene cyclases that catalyze the conversion of farnesyl diphosphate into -cadinene (Figure 23). GaWRKY 1 is a... 

Back, K. and Chappell, J. (1995) Cloning and bacterial expression of a sesquiterpene cyclase from Hyoscyamus muticus and its molecular comparison to related terpene cyclases. /. Biol. Chem., 270, 7375-81. 

Keller, H., Czernic, P, Ponchet, M., Ducrot, P.H., Back, K., Chappell, J., Ricci, P. and Marco, Y. (1998a) Sesquiterpene cyclase is not a determining factor for elicitor-induced and pathogen-induced capsidiol accumulation in tobacco. Planta, 205, 467-76. 

Zook, M.N., Chappell, J. and Kuc, J.A. (1992) Characterization of elicitor-induction of sesquiterpene cyclase activity in potato tuber tissue. Phytochemistry, 31,3441-5. 

Direct-defense compounds can be either constitutively present in (specific parts of) the plant or be produced after induction by pathogens or herbivores. The latter compound will be less costly for the plant. For example, elicitor-induced accumulation of the antimicrobial sesquiterpenoid capsidiol correlated with the induction of 5-ept-aristolochene synthase, which is a branch-point sesquiterpene cyclase involved in the synthesis of sesquiterpene phytoalexins (8). In rice Oryza saliva L.), 14 diterpenoid phytoalexins have been identified. All these compounds are accumulated in rice leaves after inoculation with the... 

Vogeh U, Freeman JW, Chappell J. Purification and characterization of an inducible sesquiterpene cyclase from elicitor-treated tobacco cell suspension cultures. Plant Physiol. 1990 93 182-187. 

Hohn TM, Beremand PD (1989) Isolation and Nucleotide Sequenee of a Sesquiterpene Cyclase Gene from the Trichothecene-Producing Fungus Fusarium sporotrichioides. Gene 79 131... 

Hohn TM, Ohfrogge IB (1991) Expression of a Fungal Sesquiterpene Cyclase Gene in Transgenic Tobacco. Plant Physiol 97 460... 

Dehal, S. S. and R. Croteau, Partial purification and characterization of two sesquiterpene cyclases from sage (Salvia officinalis) which catalyze the respective conversion of famesyl pyrophosphate to humulene and caryophyllene. Arch. Biochem. Biophys., 261, 346-356 (1988). 

The nearly complete catalytic intolerance for glutamyl and alanyl substitutions in the DDxxD motif of limonene synthase is novel and unlike the much less pronounced effects of comparable substitutions in the sesquiterpene cyclase trichodiene synthase [97, 98]. However, pre-steady state kinetic analysis of trichodiene synthase [101] and several other sesquiterpene synthases [102] has recently shown that product release is rate limiting in these cases, and thus can mask the kinetic influence of the aspartate mutations on earlier steps in the catalytic cycle. In the instance of monoterpene cyclase catalysis, product release is not the slow step since comparison of k at values with GPP and LPP as substrate clearly reveals the initial ionization-isomerization to be rate limiting. Thus, perturbations that influence the first ionization step will be fully reflected in overall rate suppression for limonene synthase. This kinetic sensitivity at the initial steps of the reaction cycle does not, however, explain the near complete intolerance of limonene synthase to aspartate substitution in the DDxxD motif and it is thus tempting to speculate a more specific, but presently unidentified, influence on the requisite isomerization of GPP. 

Although the primary structures of the microbial sesquiterpene cyclases share little with their plant counterparts, similar tertiary structures, common electrophilic reaction mechanisms, and conservation of the DDxxD substrate binding motif make it instructive to describe trichodiene synthase from Fusarium sporotrichioidesy about which considerable information is available. 

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