Maintenance and integrity of the mitochondrial genome: a plethora of nuclear genes in the budding yeast.
Instability of the mitochondrial genome (mtDNA) is a general problem from yeasts to humans. However, its genetic control is not well documented except in the yeast Saccharomyces cerevisiae. From the discovery, 50 years ago, of the petite mutants by Ephrussi and his coworkers, it has been shown that more than 100 nuclear genes directly or indirectly influence the fate of the rho(+) mtDNA. It is not surprising that mutations in genes involved in mtDNA metabolism (replication, repair, and recombination) can cause a complete loss of mtDNA (rho(0) petites) and/or lead to truncated forms (rho(-)) of this genome. However, most loss-of-function mutations which increase yeast mtDNA instability act indirectly: they lie in genes controlling functions as diverse as mitochondrial translation, ATP synthase, iron homeostasis, fatty acid metabolism, mitochondrial morphology, and so on. In a few cases it has been shown that gene overexpression increases the levels of petite mutants. Mutations in other genes are lethal in the absence of a functional mtDNA and thus convert this petite-positive yeast into a petite-negative form: petite cells cannot be recovered in these genetic contexts. Most of the data are explained if one assumes that the maintenance of the rho(+) genome depends on a centromere-like structure dispensable for the maintenance of rho(-) mtDNA and/or the function of mitochondrially encoded ATP synthase subunits, especially ATP6. In fact, the real challenge for the next 50 years will be to assemble the pieces of this puzzle by using yeast and to use complementary models, especially in strict aerobes.
Contamine
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Institut de Génétique et Microbiologie, UMR 8621, Université Paris-Sud, 91405 Orsay Cedex, France.
Picard
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D000251:Adenosine Triphosphatases / Q000235:genetics / Q000378:metabolism; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism; D002453:Cell Cycle / Q000502:physiology; D004260:DNA Repair / Q000235:genetics; D004272:DNA, Mitochondrial / Q000235:genetics*; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D004706:Endodeoxyribonucleases / Q000235:genetics / Q000378:metabolism; D015966:Gene Expression Regulation, Fungal; D005800:Genes, Fungal; D016681:Genome, Fungal; D045565:Holliday Junction Resolvases; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism; D014176:Protein Biosynthesis; D011499:Protein Processing, Post-Translational; D011995:Recombination, Genetic; D012441:Saccharomyces cerevisiae / Q000235:genetics* / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism; D019014:fas Receptor / Q000378:metabolism
C072843:ABF2 protein, S cerevisiae; D002352:Carrier Proteins; D004272:DNA, Mitochondrial; D004268:DNA-Binding Proteins; D009687:Nuclear Proteins; D029701:Saccharomyces cerevisiae Proteins; D014157:Transcription Factors; D019014:fas Receptor; D004706:Endodeoxyribonucleases; C473486:CCE1 protein, S cerevisiae; D045565:Holliday Junction Resolvases; D000251:Adenosine Triphosphatases