Isolation and characterization of Isopentenyl‐diphosphate Isomerase (idi) from marine bacterium, Kocuria gwangalliensis

Abstract

Isoprenoid biosynthesis involves mostly head to tail addition of isopentenyl diphosphate (IPP), to its isomer dimethylallyl diphosphate (DMAPP) synthesizing geranyl diphosphate (GPP). Isopentenyl diphosphate (IPP) isomerase catalyses the interconversion of IPP to dimethylallyl diphosphate (DMAPP). In the present study, the gene coding for Isopentenyl‐diphosphate Isomerase (idi) was isolated from the marine bacterium, Kocuria gwangalliensis. The idi gene coding for IPP isomerase consists of 543 base pairs encoding 180 amino acids residues. The nucleotide sequence of the idi gene was analyzed and compared with that of other species, including K. rhizophila and S. keddieii, and it turned out to be well conserved during evolution. An expression plasmid containing the idi gene was constructed and expressed in E. coli, and produced a recombinant protein of approximately 20 kDa, corresponding to the molecular weight. In order to increase production of astaxanthin, pET‐44a(+)‐idi was co‐transformed into E. coli containing the pCR‐XL‐TOPO‐crt‐full carrying crtEBIYWZ genes required for astaxanthin biosynthesis. This engineered E.coli strain containing both idi gene and astaxanthin biosythesis gene cluster produced 900 ug/g DCW of astaxanthin, resulting 2‐fold increased production of astaxanthin.