A yeast model of the neurogenic ataxia retinitis pigmentosa (NARP) T8993G mutation in the mitochondrial ATP synthase-6 gene.

Abstract

NARP (neuropathy, ataxia, and retinitis pigmentosa) and MILS (maternally inherited Leigh syndrome) are mitochondrial disorders associated with point mutations of the mitochondrial DNA (mtDNA) in the gene encoding the Atp6p subunit of the ATP synthase. The most common and studied of these mutations is T8993G converting the highly conserved leucine 156 into arginine. We have introduced this mutation at the corresponding position (183) of yeast Saccharomyces cerevisiae mitochondrially encoded Atp6p. The "yeast NARP mutant" grew very slowly on respiratory substrates, possibly because mitochondrial ATP synthesis was only 10% of the wild type level. The mutated ATP synthase was found to be correctly assembled and present at nearly normal levels (80% of the wild type). Contrary to what has been reported for human NARP cells, the reverse functioning of the ATP synthase, i.e. ATP hydrolysis in the F(1) coupled to F(0)-mediated proton translocation out of the mitochondrial matrix, was significantly compromised in the yeast NARP mutant. Interestingly, the oxygen consumption rate in the yeast NARP mutant was decreased by about 80% compared with the wild type, due to a selective lowering in cytochrome c oxidase (complex IV) content. This finding suggests a possible regulatory mechanism between ATP synthase activity and complex IV expression in yeast mitochondria. The availability of a yeast NARP model could ease the search for rescuing mechanisms against this mitochondrial disease.

• Authors: Malgorzata Rak, Emmanuel Tetaud, Stéphane Duvezin-Caubet, Nahia Ezkurdia, Maïlis Bietenhader, Joanna Rytka, Jean-Paul di Rago
• Journal: The Journal of biological chemistry (J Biol Chem) Vol. 282 Issue 47 Pg. 34039-47 (Nov 23 2007) ISSN: 0021-9258 [Print] United States
• PMID: 17855363 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• ATP6 protein, S cerevisiae
• Protons
• Saccharomyces cerevisiae Proteins
• Adenosine Triphosphate
• Electron Transport Complex IV
• Mitochondrial Proton-Translocating ATPases

Topics

• Adenosine Triphosphate (biosynthesis, genetics)
• Amino Acid Substitution
• Ataxia (enzymology, genetics)
• Electron Transport Complex IV (genetics, metabolism)
• Hydrolysis
• Leigh Disease (enzymology)
• Mitochondria (enzymology, genetics)
• Mitochondrial Proton-Translocating ATPases (genetics, metabolism)
• Models, Biological
• Mutation, Missense
• Oxygen Consumption (genetics)
• Protons
• Retinitis Pigmentosa (enzymology, genetics)
• Saccharomyces cerevisiae (enzymology, genetics, growth & development)
• Saccharomyces cerevisiae Proteins (genetics, metabolism)