It has been known that ubiquinone (UQ or coenzyme Q) is an essential component of the respiratory chain and oxidative phosphorylation in many organisms. Ubiquinone is comprised from two components, quinone structure and isoprenoid chain.
The side chain length of ubiquinone is specific in each organisms. Saccharomyces cerevisiae has UQ-6, E. coli has UQ-8, rat and R. capsulatus have UQ-9 and S. pombe, G. suboxydans and human have UQ-10. Among them, UQ-10 is very useful, because it is commercially used as a drug for heart disease.
Recently, we reported that UQ has an important role as an antioxidant in Schizosaccharomyces pombe. S. pombe mutant which does not produce ubiquinone-10 can not grown on minimal medium. When cysteine, glutathione or alpha-tocopherol was added in the medium, non-UQ produced S. pombe could restore the growth. Suzuki, K. et al. (1997) J. Biochem. (Tokyo) 121, 496.
What does the side chain length of ubiquinone determine?
Polyprenyl diphosphate synthases determine the side chain length of ubiquinone. Okada, K. et al. (1996) Biochim. Biophys. Acta 1302, 217.
E. coli ordinarily produce UQ-8, but E. coli transformed with decaprenyl diphosphate synthase gene from G. suboxydans could produce UQ-10. In the similar ways, E. coli transformed with heptaprenyl or solanesyl diphosphate synthase gene from H. influenzae or R. capsulatus could produce UQ-7 or UQ-9. Okada, K. et al. (1997) J. Bacteriol. 179, 3058., Okada, K. et al. (1997) J. Bacteriol. 179, 5992., Okada, K. et al. (1998) Eur. J. Biochem.255, 52.
Similarly, S. cerevisiae could produce UQ-5, 6, 7, 8, 9 and 10. Okada, K. et al. (1998) FEBS Lett. 431, 241.
We proved that the side chain length of ubiquinone could be altered by genetic engineering.
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