earticle

영어

Quinones are key constituents of the membrane-bound respiratory electron transfer chains in both prokaryotes and eukaryotes. These lipid components, containing isoprenoid side chains of various lengths, can be divided into two major structural groups, benzoquinones and
naphthoquinones. The anaerobic bacterium E. coli is capable of synthesizing octaprenyl quinones of both types, i.e. a benzoquinone, ubiquinone-8 (Q-8), and two types of naphthoquinone, menaquinone-8 (MQ-8) and demethylmenaquinone(DMQ). The first committed step in the biosynthesis of ubiquinone is the formation of 4-hydroxybenzoate from chorismate mediated by the enzyme chorismate pyruvate lyase encoded by the ubiC gene. The 4-hydroxybenzoate is subsequently prenylated by the enzyme 4-hydroxybenzoate ctaprenyltransferase encoded by the ubiA gene. In this study, Escherichia coli quinone
biosynthetic pathway was metabolically engineered to improve the yield of quinone compounds. Proteomic analysis was then carried out to understand the effect of metabolic/genetic changes on the proteome of the engineered E. coli. The ubiCA deletion mutant produced higher amount of quinone compounds than wild-type E. coli, indicating than metabolic flux was redirected towards quinone formation. Enhanced quinone formation was observed when pathway enzymes ispA, idi, dxr or menD was overexpressed in the deletion mutant. Proteome analysis disclosed different proteins expression profiling between mutant and wild-type E. coli.