Chimeras of Two Isoprenoid Synthases Catalyze All Four Coupling Reactions in Isoprenoid Biosynthesis

Abstract

The carbon skeletons of over 55,000 naturally occurring isoprenoid compounds are constructed from four fundamental coupling reactions: chain elongation, cyclopropanation, branching, and cyclobutanation. Enzymes that catalyze chain elongation and cyclopropanation are well studied, whereas those that catalyze branching and cyclobutanation are unknown. We have catalyzed the four reactions with chimeric proteins generated by replacing segments of a chain-elongation enzyme with corresponding sequences from a cyclopropanation enzyme. Stereochemical and mechanistic considerations suggest that the four coupling enzymes could have evolved from a common ancestor through relatively small changes in the catalytic site.

Chrysanthemyl Diphosphate Synthase Operates in Planta as a Bifunctional Enzyme with Chrysanthemol Synthase Activity

“…For identification of lavandulol, mass spectra of eluted peak fractions were compared with the published mass spectrum for lavandulol (11).…”

“…The final step of the esterification of chrysanthemic acid with one of the lipid alcohols is performed by a recently cloned GDSL lipase from pyrethrum. This enzyme transfers the chrysanthemoyl group from the CoA thioester to pyrethrolone to produce pyrethrin I but does so in the pericarp of the seeds and not in the glandular trichomes (9,10 CDS, the enzyme catalyzing the first pathway-specific step, evolved from farnesyl diphosphate synthase (FDS) (8,11,12). It takes two molecules of DMAPP as substrate to produce CPP as major product and lavandulyl diphosphate (LPP) as minor product (Fig.…”

“…For the identification of chrysanthemol, the authentic standard of chrysanthemol was run under identical conditions. For identification of lavandulol, the mass spectrum of the eluted peak was compared with the published mass spectrum of lavandulol (11). The third leaf from the top was used for non-volatile analysis according to a protocol for untargeted metabolomics of plant tissues (33) as described in detail previously (32).…”

Bidirectional Secretions from Glandular Trichomes of Pyrethrum Enable Immunization of Seedlings

“…CDS evolved relatively recently after a gene duplication from an ancestral farnesyl diphosphate synthase (FDS) gene. In that process, it acquired a plastid targeting signal, which enabled access to DMAPP derived from the methylerythritol-4-phosphate (MEP) pathway (Rivera et al, 2001;Thulasiram et al, 2007). Very recently, a second dedicated enzyme, T. cinerariifolium GDSL Lipase-like Protein (GLIP), responsible for the specific esterification of chrysanthemoyl-CoA thioester and pyrethrolone to form pyrethrin I, was discovered (Kikuta et al, 2012).…”

POLYPRENOL REDUCTASE2 Deficiency Is Lethal in Arabidopsis Due to Male Sterility

“…Dolichol (Dol) is a member of the isoprenoids, which are functionally and structurally the most diverse group of natural products (Thulasiram et al, 2007). Dolichyl phosphate (Dol-P) as a cofactor is necessary for protein glycosylation, a ubiquitous posttranslational modification found in all domains of life (Pattison and Amtmann, 2009;Schwarz and Aebi, 2011).…”