Fig. 1
Biosynthesis of isoprene and isoprenoids via the mevalonate (MVA) and non-mevalonate or methylerythritol phosphate (MEP) pathways, with isopentenyl diphosphate (IPP) and dimethylallyl diphosphate (DMAPP) as key intermediates. Mevalonate pathway enzymes shown are: AACT acetoacetyl-CoA thiolase, HMGS 3-hydroxy-3-methylglutaryl-CoA synthase, HMGR 3-hydroxy-3-methylglutaryl-CoA reductase, MK mevalonate kinase, PMK phosphomevalonate kinase, MDC mevalonate 5-diphosphate decarboxylase. Note that an alternative route exists in Archaea for the conversion of mevalonate-5-phosphate to IPP [81]. MEP Pathway enzymes shown are: DXPS 1-deoxyxylulose 5-phosphate synthase, DXR 1-deoxyxylulose 5-phosphate reductoisomerase, MCT 2-C-methyl-D-erythritol 4-phosphate cytidyl transferase, CMK 4-(cytidine 5′-diphospho)-2-C-methyl-D-erythritol kinase, MECPS 2-C-methyl-D-erythritol-2,4-cyclodiphosphate synthase. The intermediate, (E)-4-hydroxy-3-methylbut-2-en-1-yl diphosphate (HMBPP), from 2-C-methyl-d-erythritol-2,4-cyclodiphosphate to IPP and DMAPP, is not shown. Enzymes common to both pathways are: IPPI isopentenyl diphosphate isomerase, ISPS isoprene synthase. Modified from Lange et al. [82] and Steinke et al. [83]
