Biosynthesis of 2-C-methyl-D-erythritol-2,4-cyclopyrophosphate in bacteria

Corynebacterium ammoniagenes mutants capable of accumulating 2-C-methyl-D-erythritol-2,4-cyclopyrophosphate (MEC) in the absence of an exogenous oxidative stress inducer were obtained. At the logarithmic growth phase, these mutants displayed decreased superoxide dismutase (SOD) activity and synthesized lower amounts of isoprenoids (carotenoids and naphthoquinones) than wild-type cells. Screening the microorganisms for the capacity for MEC accumulation revealed such bacteria among the gram-negative, facultative animal and plant parasites Xanthomonas campestris, X, maltophilia, and Pseudomonas putida. Iodoacetate did not inhibit MEC biosynthesis in corynebacteria, and no preferential incorporation of radiolabeled C-1 or C-6 atoms of glucose into the MEC molecule was observed, which was in agreement with the recently suggested scheme of a mevalonate-independent pathway of isoprenoid biosynthesis, in which MEC is believed to be an intermediate.