Insight into C35 terpene biosyntheses by nonpathogenic Mycobacterium Species: functional analyses of three Z-prenyltransferases and identification of dehydroheptaprenylcyclines.

Nonpathogenic Mycobacterium species produce rare cyclic C(35) terpenes that are biosynthesized by cyclization of Z-type C(35) polyprenyl diphosphate. To provide deeper insight into the biosynthesis of C(35) terpenes, we carried out functional analyses of three Z-prenyltransferase homologues in M. vanbaalenii identified by genomic analysis. Mvan_3822, a novel bifunctional Z-prenyltransferase, biosynthesizes C(35)-heptaprenyl diphosphate as a main product from (E,E)-farnesyl diphosphate (E,E-FPP) and (E,E,E)-geranylgeranyl diphosphate (E,E,E-GGPP), but produces a C(50)-decaprenyl diphosphate from geranyl diphosphate. Mvan_1705 is a novel Z,E,E-GGPP synthase. In addition, novel cyclic C(35) terpenes, (14E)- and (14Z)-dehydroheptaprenylcycline, were identified as minor metabolites in nonpathogenic Mycobacterium cells. C(35) terpenes could be biosynthesized by two routes, in which E and Z geometric isomers of heptaprenyl diphosphate are produced from E,E-FPP and E,E,E-GGPP, and the prenylreductase responsible for the biosynthesis of C(35) terpenes could reduce both E and Z prenyl residues.