Studies on the nonmevalonate pathway to terpenes: The role of the GcpE (IspG) protein

Abstract
Recombinant Escherichia coli cells engineered for the expression of the xylB gene in conjunction with genes of the nonmevalonate pathway were supplied with 13 C-labeled 1-deoxy- d -xylulose. Cell extracts were analyzed directly by NMR spectroscopy. 13 C-labeled 2 C -methyl- d -erythritol 2,4-cyclodiphosphate was detected at high levels in cells expressing xylB , ispC , ispD , ispE, and ispF . The additional expression of the gcpE gene afforded 1-hydroxy-2-methyl-2-( E )-butenyl 4-diphosphate as an intermediate of the nonmevalonate pathway. Hypothetical mechanisms involving conserved cysteine residues are proposed for the enzymatic conversion of 2 C -methyl- d -erythritol 2,4-cyclodiphosphate into 1-hydroxy-2-methyl-2-( E )-butenyl 4-diphosphate catalyzed by the GcpE protein.