Overexpression, purification and characterization of geranylgeranyl pyrophosphate synthase from marine bacterium, Paracoccus haeundaensis

Abstract

Carotenoids such as β-carotene and astaxanthin are used as food colorants, animal feed supplements and for nutritional and cosmetic purposes. Recently, carotenoids have received a great attention for their significant antioxidant activities and for playing an important role in inhibiting the onset of chronic diseases. In addition to its antioxidative activity, astaxanthin has been shown to gave biological functions as diverse as serving as a vitamin A precursor, enhancing gap junction communications, and modulating the immune system. A carotenoid biosynthesis gene cluster for the production of astaxanthin was isolated from the marine bacterium Paracoccus haeundaensis. Early steps in the biosynthesis of carotenoid include the formation of the C20 compound geranylgeranyl pyrophosphate (GGPP) from farnesyl pyrophosphate (FPP) by GGPP synthase, an enzyme encoded by the crtE gene. Geranylgeranyl (GGPP) synthase is thought to be a key enzyme in the carotenoid biosynthesis pathway. In order to obtain a large quantity of the purified GGPP synthase, the crtE gene was subcloned into pET-44a(+) expression vector, transformed into the E. coli BL21(DE) codon plus cell, and the expressed protein was purified to homogeneity by affinity chromatographic method. Finally, the biochemical properties of the purified GGPP synthase have been characterized