Advertisement

Springer Nature is making SARS-CoV-2 and COVID-19 research free. View research | View latest news | Sign up for updates

Relocation of urf a from the mitochondrion to the nucleus cures the mitochondrial mutator phenotype in the fission yeast Schizosaccharomyces pombe

Abstract

In previous papers we have reported the characterisation of mitochondrial mutator mutants of Schizosaccharomyces pombe. In contrast to nuclear mutator mutants known from other eucaryotes, this mutator phenotype correlates with mutations in an unassigned open reading frame (urf a) in the mitochondrial genome. Since an efficient biolistic transformation system for fission yeast mitochondria is not yet available, we relocated the mitochondrial urf a gene to the nucleus. As host strain for the ectopic expression, we used the nonsense mutant ana r -6, which carries a premature stop codon in the urf a gene. The phenotype of this mutant is characterised by continuous segregation of progeny giving rise to fully respiration competent colonies, colonies that show moderate growth on glycerol and a fraction of colonies that are unable to grow on glycerol. The phenotype of this mutant provides an excellent tool with which to study the effects on the mutator phenotype of ectopic expression of the urf a gene. Since a UGA codon encoding tryptophan is present in the original mitochondrial gene, we constructed two types of expression cassettes containing either the mitochondrial version of the urf a gene (mt-urf a) or a standard genetic code version (nc-urf a; UGA replaced by UGG) fused to the N-terminal import leader sequence of the cox4 gene of Saccharomyces cerevisiae. We show that the expression of the mt-urf a gene in its new location is able to cure, at least in part, the phenotype of mutant ana r -6, whereas the expression of the nc-urf a gene completely restores the wild-type (non-mutator) phenotype. The significant similarity of the urf a gene to the mitochondrial var1 gene of S. cerevisiae and homologous genes in other yeasts suggests that the urf a gene product might be a ribosomal protein with a dual function in protein synthesis and maintenance of mitochondrial DNA integrity.

This is a preview of subscription content, log in to check access.

Author information

Additional information

Received: 13 May 1997 / Accepted: 14 January 1998

Rights and permissions

Reprints and Permissions

About this article

Cite this article

Neu, R., Goffart, S., Wolf, K. et al. Relocation of urf a from the mitochondrion to the nucleus cures the mitochondrial mutator phenotype in the fission yeast Schizosaccharomyces pombe . Mol Gen Genet 258, 389–396 (1998). https://doi.org/10.1007/s004380050746

Download citation

  • Key words Fission yeast
  • Ectopic expression
  • var1 gene
  • Mutator
  • Ribosomal protein