Methylerythritol

Methylerythritol, or 2-C-methyl-D-erythritol, is a methylated derivative of the sugar alcohol erythritol. In biochemistry, the term often refers to its phosphorylated form, 2-C-methyl-D-erythritol 4-phosphate (MEP), which is an intermediate in the non-mevalonate pathway of isoprenoid biosynthesis.

Biological context and distribution

The methylerythritol/MEP family plays a central role in the MEP pathway, a sequence of enzymatic reactions that converts simple sugar-derived substrates into isoprenoid precursors. This pathway operates in many bacteria, most algae, and plant plastids, including higher plants and certain parasites. In contrast, animals, including humans, do not possess the MEP pathway and rely on the mevalonate pathway for isoprenoid production.

Chemical and biosynthetic role

MEP and its related compounds are essential intermediates that lead to the formation of isopentenyl pyrophosphate (IPP) and dimethylallyl pyrophosphate (DMAPP), the universal building blocks for a wide range of isoprenoids such as quinones, chlorophylls, carotenoids, and various prenylated proteins. The pathway begins with pyruvate and glyceraldehyde-3-phosphate and proceeds through several phosphorylation and rearrangement steps to produce IPP and DMAPP.

Medical and research relevance

Because the MEP pathway is absent in humans but present in many pathogens, its enzymes are targets for antibiotics and herbicides. Inhibitors like fosmidomycin block the pathway and disrupt microbial isoprenoid biosynthesis. Research into methylerythritol and the MEP pathway aids metabolic engineering of plants and microbes to alter isoprenoid production for agricultural and pharmaceutical applications.