Fig. 1.

Identification of a putative hopanoid biosynthetic gene cluster in R. palustris TIE-1. (A) The shc locus (Gray Arrow), which is required for hopanoid biosynthesis, is surrounded by several putative hopanoid biosynthesis genes. Upstream of shc, a hypothetical B-12 binding radical SAM protein was identified (hpnP, Black Arrow) as a C-2 methylase candidate. (B) The structure of the six C-2 methylated triterpenoids produced by R. palustris TIE-1: three 2-methylhopenes (hop-22(29)-ene, hop-17(21)-ene, and hop-21-ene), 2-methyldiplopterol, 2-methyltetrahymanol, and 2-methylbacteriohopanetetrol.