Identification of a Mono-Phosphomevalonate Decarboxylase and Utilization for Production of Isoprene without a Diphosphomevalonate Intermediate

Isoprenoids are secondary metabolites having value in a variety of commercial uses. At least three routes for the biosynthesis of isoprenoids have evolved, including two sequentially distinct routes from phosphomevalonate (MVP) to isopentenyl pyrophosphate in which the intermediate is phosphorylated and then decarboxylated (typical for eukaryotes) or decarboxylated and then phosphorylated (predicted for archaea). We have identified a MVP decarboxylase that completes the suite of enzymes needed for the predicted archaeal route. Isoprene production pathways following both the conventional eukaryotic route and this new route were used to bioconvert MVA to isoprene in E.coli at over 10 mg/L/hr/OD. This study demonstrates the value of applying synthetic biology not only to quantitative traits (e.g., expression level and kinetic parameters) but also qualitative aspects (e.g., chemical route) for pathway engineering. Such qualitative changes can be used to eliminate toxic heterologous metabolites, avoid interfering with endogenous pathways, and implement chemistries with improved fermentation performance.