Pleiotropic phenotypes of fission yeast defective in ubiquinone‐10 production. A study from the abc1Sp (coq8Sp) mutant

Abstract

We previously constructed two Schizosaccahromyces pombe ubiquinone-10 (or Coenzyme Q10) less mutants, which are either defective for decaprenyl diphosphate synthase or p-hydroxybenzoate polyprenyl diphosphate transferase. To further confirm the roles of ubiquinone in S. pombe, we examined the phenotype of the abc1Sp (coq8Sp) mutant, which is highly speculated to be defective in ubiquinone biosynthesis. We show here that the abc1Sp defective strain did not produce UQ-10 and could not grow on minimal medium. The abc1Sp-deficient strain required supplementation with antioxidants such as cysteine or glutathione to grow on minimal medium. In support of the antioxidant function of ubiquinone, the abc1Sp-deficient strain is sensitive to H2O2 and Cu2+. In addition, expression of the stress inducible ctt1 gene was much induced in the ubiquinone less mutant than wild type. Interestingly, we also found that the abc1-deficient strain as well as other ubiquinone less mutants produced a significant amount of H2S, which suggests that oxidation of sulfide by ubiquinone may be an important pathway for sulfur metabolism in S. pombe. Thus, analysis of the phenotypes of S. pombe ubiquinone less mutants clearly demonstrate that ubiquinone has multiple functions in the cell apart from being an integral component of the electron transfer system.

The AtPPT1 gene encoding 4-hydroxybenzoate polyprenyl diphosphate transferase in ubiquinone biosynthesis is required for embryo development in Arabidopsis thaliana

“…Several reports demonstrate the pleiotropic effects of UQ in non-mitochondrial cells (Saiki et al, 2003). Therefore, besides depletion of mitochondrial UQ, depletion of non-mitochondrial UQ might be the reason for the arrest of embryo development in the homozygous atppt1 mutant, as observed in mammals.…”

Involvement of a Broccoli COQ5 Methyltransferase in the Production of Volatile Selenium Compounds

“…contrast, ubiquinone-deficient mutants in E. coli and yeast are hypersensitive to hydrogen peroxide and Cu 2+ (Soballe and Poole, 2000;Saiki et al, 2003). Also, the yeast ubiquinone biosynthesis mutants are sensitive to cadmium (Kennedy et al, 2008).…”

The abc1 − /coq8 − respiratory-deficient mutant of Schizosaccharomyces pombe suffers from glutathione underproduction and hyperaccumulates Cd2+

“…The petitenegative yeasts, such as Schizosaccharomyces pombe, seem to be unable to produce viable rho 0 mutants and display limited growth under anaerobic conditions. A limited number of respiratory-deficient mutants harboring nuclear or mitochondrial mutations have been isolated from S. pombe (Saiki et al 2003;Miki et al 2008). The gene ABC1/COQ8 product has been proved to be a respirationrelated protein (abc1/coq8p) encoded in the nucleus, and is essential for the proper conformation and efficient function of the bc1 respiratory complex in both S. cerevisiae (Bousquet et al 1991) and S. pombe (Bonnefoy et al 1996).…”

“…Inactivation of the abc1Sp gene, carried out first by Bonnefoy et al (1996) by homologous gene replacement, caused a respiratory deficiency: the mutant NBp17 exhibited a drastic decrease in bc1 complex activity, a decrease in cytochrome aa3 and a slow growth phenotype in comparison with its parental strain HMT. The S. pombe abc1 − /coq8 − gene deletion mutant displayed pleiotropic phenotypes, including a lack of coenzyme Q 10 (CoQ 10 ) biosynthesis, increased sensitivities to H 2 O 2 and Cu 2+ , and H 2 S overproduction (Saiki et al 2003).…”