FIG 1.

Isoprenoid biosynthesis pathways and macromolecular compositions of representative bacteria, eukarya, and archaea. (a) Isoprene is synthesized from isopentenyl pyrophosphate/dimethylallyl pyrophosphate (IPP/DMAPP) derived from glucose via the methylerythritol phosphate/deoxy xylulose phosphate (MEP/DOXP) pathway in bacteria or mevalonate (MVA) pathway in eukarya. (b and c) Relative amounts of macromolecules in E. coli bacterium (58) and S. cerevisiae yeast (59), respectively. (d) Isoprenoid lipids are synthesized from IPP/DMAPP by the archaeal MVA pathway in methanogens. (e) Isoprenoid lipids in methanogens comprise 5% of biomass dry weight (29). Arrow sizes and line widths depict published carbon fluxes through each pathway. One or more genes are required for most organisms to produce isoprene monomer (red arrows). See Table S1 for macromolecular composition values shown in panels b, c, and e.