Biosynthesis and bioproduction of coenzyme Q_(10) by yeasts and other organisms

摘要

CoQ (coenzyme Q), an isoprenylated benzoquinone, is a well-known component of the electron-transfer system in eukaryotes. The main role of CoQ is to transfer electrons from NADH dehydrogenase and succinate dehydrogenase to CoQ:cytochrome c reductase in the respiratory chain. However, recent evidence indicates that an involvement in respiration is not the only role of CoQ. The second apparent role of CoQ is its anti-oxidation property, and other novel roles for CoQ, such as in disulfide-bond formation, sulfide oxidation and pyrimidine metabolism, have been reported. CoQ_(10), having ten isoprene units in the isoprenoid side chain, has been used as a medicine and is now commercially popular as a food supplement. Two yeast species, namely the budding yeast Saccharomyces cerevisiae, which produces CoQ_6, and the fission yeast Schizosaccharomyces pombe, which produces CoQ_(10), are the main subjects of the present minireview because they have greatly contributed to our basic knowledge of CoQ biosynthesis among eukaryotes. The biosynthetic pathway that converts p-hydroxybenzoate into CoQ consists of eight steps in yeasts. The five en_zymes involved in the biosynthetic pathway have been identified in both yeasts, yet the functions of three proteins were still not known. Analyses of the bio_synthetic pathway in yeasts also contribute to the understanding of human genetic diseases related to CoQ deficiency. In the present minireview I focus on the biochemical and commercial aspects of CoQ in yeasts and in other organisms for comparison.