Escherichia coli engineered to synthesize isopentenyl diphosphate and dimethylallyl diphosphate from mevalonate: a novel system for the genetic analysis of the 2-C-methyl-D-erythritol 4-phosphate pathway for isoprenoid biosynthesis

Isopentenyl diphosphate (IPP) and its isomer dimethylallyl diphosphate (DMA PP) constitute the basic building block of isoprenoids, a family of compoun ds that is extraordinarily diverse in structure and function. IPP and DMAPP can be synthesized by two independent pathways: the mevalonate pathway and the recently discovered 2-C-methyl-D-erythritol 4-phosphate (MEP) pathway. Although the MEP pathway is essential in most eubacteria, algae and plants and has enormous biotechnological interest, only some of its steps have be en determined. We devised a system suitable for the genetic analysis of the MEP pathway in Escherichia coli, A synthetic operon coding for yeast 5-dip hosphomevalonate decarboxylase, human 5-phosphomevalonate kinase, yeast mev alonate kinase and E. coli isopentenyl diphosphate isomerase was incorporat ed in the chromosome of this bacterium. The expression of this operon allow ed the synthesis of IPP and DMAPP from mevalonate added exogenously and com plementation of lethal mutants of the MEP pathway. We used this system to s how that the ygbP, ychB and ygbB genes are essential in E. coli and that th e steps catalysed by the products of these genes belong to the trunk line o f the MEP pathway.