2-C-Methyl-d-erythritol-2,4-cyclopyrophosphate (MEcPP) (also 2-C-Methyl-d-erythritol-2,4-cyclodiphosphate) is an intermediate in the
MEP pathway (non-mevalonate) of
isoprenoid precursor biosynthesis.[1] MEcPP is produced by
MEcPP synthase (IspF) and is a substrate for
HMB-PP synthase (IspG).
Under conditions of oxidative stress, MEcPP accumulates in certain bacteria.[2] MEcPP releases histone-like proteins from DNA, triggering
nucleoid decondensation in Chlamydia trachomatis during the process of terminal differentiation.[3] Abiotic stresses to plants, including wounding and excessive high-light exposure, lead to an increase in MEcPP accumulation in
chloroplasts. Transported from the chloroplast to the plant cell
nucleus, MEcPP engages in
retrograde signalling that leads to the specific induction of
nuclear-encoded stress-response genes.[4]