Versatile cis-isoprenyl Diphosphate Synthase Superfamily Members in Catalyzing Carbon-Carbon Bond Formation

Abstract

Isoprenyl diphosphate synthases (IDSs) catalyze condensation reactions of isoprene units to produce isoprenoids or terpenoids, the largest class of natural products on earth. IDSs are divided into trans- and cis-IDS superfamilies depending on the configuration of the resulting carbon-carbon double bonds. Compared with trans-IDSs, cis-IDS family members exhibit more variable active site structure and versatile function. The archetypal cis-IDSs are homodimers and produce linear isoprenoids via head-to-tail condensation. Recently, heterodimeric cis-IDSs containing a noncatalytic subunit that also belongs to the cis-IDS superfamily have been identified. Moreover, several cis-IDS-fold members have been found to produce nonlinear isoprenoids via "head-to-middle" condensation. In this Review, we summarize the structural features and catalytic mechanism of the versatile cis-IDS superfamily. This information provides important guidance for research regarding biosynthesis of important natural products and medical intermediates, cellular metabolism, and disease control.