Biosynthesis of terpenoids - 2C-Methyl-D-erythritol 2,4-cyclodiphosphate synthase (IspF) from Plasmodium falciparum

The putative catalytic domain of an open reading frame from Plasmodium falc iparum with similarity to the ispF gene of Escherichia coil specifying 2C-m ethyl-D-erythritol 2,4-cyclodiphosphate synthase was expressed in a recombi nant E. coli strain. The recombinant protein was purified to homogeneity an d was found to catalyze the formation of 2C-methyl-D-erythritol 2,4-cyclodi phosphate from 4-diphosphocytidyl-2C-methyl-D-erythrito 2-phosphate at a ra te of 4.3 mu mol.mg(-1).min(-1). At lower rates, the recombinant protein ca talyzes the formation of 2-phospho-2C-methyl-D-erythritol 3,4-cyclophosphat e from 4-diphosphocytidyl-2C-methyl-D-erythritol 2-phosphate and the format ion of 2C-methyl-D-erythritol 3,4-cyclophosphate from 4-diphosphocytidyl-2C -methyl-D-erythritol. Divalent metal ions such as magnesium or manganese ar e required for catalytic activity. The enzyme has a pH optimum at pH 7.0. R ecombinant expression of the full-length open reading frame afforded insolu ble protein that could not be folded in vitro. The enzyme is a potential ta rget for antimalarial drugs directed at the nonmevalonate pathway of isopre noid biosynthesis.