:thyl-D-erythritol i-D-erythritol

In many microorganisms, the putative orthologs of the Escheric coli ygbB gene are tightly linked or fused to putative ortholog ygbP, which has been shown earlier to be involved in terpen biosynthesis. The ygbB gene of E. coli was expressed in a rec( binant E. coli strain and was shown to direct the synthesis c soluble, 17-kDa polypeptide. The recombinant protein was foi to convert 4-diphosphocytidyl-2C-methyl-D-erythritol 2-phosph into 2C-methyl-D-erythritol 2,4-cyclodiphosphate and CMP. structure of the reaction product was established by NMR sr troscopy using 13C-labeled substrate samples. The enzyme-c[ lyzed reaction requires Mn2+ or Mg2+ but no other cofactl Radioactivity from [2-14C]2C-methyl-D-erythritol 2,4-cyclodipl phate was diverted efficiently to carotenoids by isolated chroi plasts from Capsicum annuum and, thus, was established as intermediate in the deoxyxylulose phosphate pathway of isor noid biosynthesis. YgbB protein also was found to corn 4-diphosphocytidyl-2C-methyl-D-erythritol into 2C-methyl-D-ern ritol 3,4-cyclophosphate. This compound does not serve as s strate for the formation of carotenoids by isolated chromopl; and is assumed to be an in vitro product without metab relevance.