Biosynthesis and bioproduction of coenzyme Q10by yeasts andother organisms

CoQ (coenzyme Q), an isoprenylated benzoquinone,is a well-known component of the electron-transfersystem in eukaryotes. The main role of CoQ isto transfer electrons from NADH dehydrogenaseand succinate dehydrogenase to CoQ:cytochrome creductase in the respiratory chain. However, recentevidence indicates that an involvement in respirationis not the only role of CoQ. The second apparent roleof CoQ is its anti-oxidation property, and other novelroles for CoQ, such as in disulfide-bond formation,sulfide oxidation and pyrimidine metabolism, havebeen reported. CoQ10, having ten isoprene units in theisoprenoid side chain, has been used as a medicine andis now commercially popular as a food supplement. Twoyeast species, namely the budding yeast Saccharomycescerevisiae, which produces CoQ6, and the fission yeastSchizosaccharomyces pombe, which produces CoQ10,are the main subjects of the present minireviewbecause they have greatly contributed to our basicknowledge of CoQ biosynthesis among eukaryotes. Thebiosynthetic pathway that converts p-hydroxybenzoateinto CoQ consists of eight steps in yeasts. The five en-zymes involved in the biosynthetic pathway have beenidentified in both yeasts, yet the functions of threeproteins were still not known. Analyses of the bio-synthetic pathway in yeasts also contribute to theunderstanding of human genetic diseases related toCoQ deficiency. In the present minireview I focus on thebiochemical and commercial aspects of CoQ in yeastsand in other organisms for comparison.