Isolation and expression of Paracoccus denitrificans decaprenyl diphosphate synthase gene for production of ubiquinone-10 in Escherichia coli

Abstract

Ubiquinones (coenzyme Q) play important roles as an electron carrier in the mitochondrial respiratory chain and have been successfully used as an orally administrated prophylaxis and therapy for various diseases. The number of isoprene unit in the prenyl side chain of ubiquinone varies depending on the organism. This organism-dependency of the isoprene unit number is determined by the availability of the prenyl diphosphate in the cell. Paracoccus denitrificans has (all- E)-decaprenyl diphosphate (DecPP) synthase catalyzing condensation of seven molecules of isopentenyl diphosphate with (all- E)-farnesyl diphosphate to afford DecPP (C 50), the precursor of the prenyl side chain of coenzyme Q-10. To understand structure–activity relationship of prenyl chain elongating enzymes in molecular level as well as to establish a manipulation system of ubiquinone-10 in Escherichia coli cells, the structural gene encoding DecPP synthase was cloned from Paracoccus denitrificans. An overproducing system of this enzyme was constructed, and the prenyltransferase assay of the cell-free system of the transformant indicated that the recombinant protein overexpressed in E. coli cells showed distinct DecPP synthase activity. Moreover, the level of ubiquinone-10 in the transformed cells was greater than that of ubiquinone-8, which is intrinsic in wild type E. coli host cells.