Abstract
The smm1 mutation suppresses defects in mitochondrial distribution and morphology caused by the mdm1-252 mutation in the yeast Saccharomyces cerevisiae. Cells harboring only the smm1 mutation themselves display temperature-sensitive growth and aberrant mitochondrial inheritance and morphology at the nonpermissive temperature. smm1 maps to RSP5, a gene encoding an essential ubiquitin-protein ligase. The smm1 defects are suppressed by overexpression of wild-type ubiquitin but not by overexpression of mutant ubiquitin in which lysine-63 is replaced by arginine. Furthermore, overexpression of this mutant ubiquitin perturbs mitochondrial distribution and morphology in wild-type cells. Site-directed mutagenesis revealed that the ubiquitin ligase activity of Rsp5p is essential for its function in mitochondrial inheritance. A second mutation, smm2, which also suppressed mdm1-252 defects, but did not cause aberrant mitochondrial distribution and morphology, mapped to BUL1, encoding a protein interacting with Rsp5p. These results indicate that protein ubiquitination mediated by Rsp5p plays an essential role in mitochondrial inheritance, and reveal a novel function for protein ubiquitination.
Publication types
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Research Support, U.S. Gov't, P.H.S.
MeSH terms
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Adaptor Proteins, Signal Transducing*
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Amino Acid Substitution
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Carrier Proteins / genetics
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Carrier Proteins / metabolism
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Cell Cycle Proteins*
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Endosomal Sorting Complexes Required for Transport
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Fungal Proteins / genetics
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Fungal Proteins / metabolism*
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Gene Expression
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Genes, Essential / genetics
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Genes, Fungal / genetics
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Genes, Fungal / physiology
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Genes, Suppressor / genetics
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Genetic Complementation Test
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Intermediate Filament Proteins
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Ligases / genetics
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Ligases / metabolism
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Mitochondria / genetics
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Mitochondria / physiology*
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Mutation
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Phenotype
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Protein Binding
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Saccharomyces cerevisiae / cytology*
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Saccharomyces cerevisiae / enzymology
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Saccharomyces cerevisiae / genetics
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Saccharomyces cerevisiae / growth & development
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Saccharomyces cerevisiae Proteins*
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Suppression, Genetic
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Temperature
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Ubiquitin-Protein Ligase Complexes*
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Ubiquitin-Protein Ligases
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Ubiquitins / genetics
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Ubiquitins / metabolism
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Ubiquitins / physiology*
Substances
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Adaptor Proteins, Signal Transducing
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BUL1 protein, S cerevisiae
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Carrier Proteins
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Cell Cycle Proteins
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Endosomal Sorting Complexes Required for Transport
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Fungal Proteins
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Intermediate Filament Proteins
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MDM1 protein, S cerevisiae
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Saccharomyces cerevisiae Proteins
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Ubiquitins
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Ubiquitin-Protein Ligase Complexes
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Ubiquitin-Protein Ligases
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Ligases
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RSP5 protein, S cerevisiae