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The yeast dynamin-like protein, Mgm1p, functions on the mitochondrial outer membrane to mediate mitochondrial inheritance.

Shepard KA, Yaffe MP - J. Cell Biol. (1999)

Bottom Line: It also caused aberrant mitochondrial distribution and morphology when expressed at high levels in cells that also contained a wild-type copy of the gene.Mgm1p was localized to the mitochondrial outer membrane and fractionated as a component of a high molecular weight complex.These results indicate that Mgm1p is a mitochondrial inheritance and morphology component that functions on the mitochondrial surface.

View Article: PubMed Central - PubMed

Affiliation: Department of Biology, University of California, San Diego, La Jolla, California 92093-0347, USA.

ABSTRACT
The mdm17 mutation causes temperature-dependent defects in mitochondrial inheritance, mitochondrial morphology, and the maintenance of mitochondrial DNA in the yeast Saccharomyces cerevisiae. Defects in mitochondrial transmission to daughter buds and changes in mitochondrial morphology were apparent within 30 min after shifting cells to 37 degrees C, while loss of the mitochondrial genome occurred after 4-24 h at the elevated temperature. The mdm17 lesion mapped to MGM1, a gene encoding a dynamin-like GTPase previously implicated in mitochondrial genome maintenance, and the cloned MGM1 gene complements all of the mdm17 mutant phenotypes. Cells with an mgm1- mutation displayed aberrant mitochondrial inheritance and morphology. A version of mgm1 mutated in a conserved residue in the putative GTP-binding site was unable to complement any of the mutant defects. It also caused aberrant mitochondrial distribution and morphology when expressed at high levels in cells that also contained a wild-type copy of the gene. Mgm1p was localized to the mitochondrial outer membrane and fractionated as a component of a high molecular weight complex. These results indicate that Mgm1p is a mitochondrial inheritance and morphology component that functions on the mitochondrial surface.

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mdm17 cells are conditionally defective for mitochondrial inheritance and mitochondrial morphology.  Wild-type (MYY291) and mdm17 (MYY972) cells were  grown at 23°C in YPD-liquid medium and incubated at  (A) 23°C or (B) 37°C for 4 h. Mitochondria were stained  with DASPMI and visualized by fluorescence microscopy. Bar, 2 μm.
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Figure 1: mdm17 cells are conditionally defective for mitochondrial inheritance and mitochondrial morphology. Wild-type (MYY291) and mdm17 (MYY972) cells were grown at 23°C in YPD-liquid medium and incubated at (A) 23°C or (B) 37°C for 4 h. Mitochondria were stained with DASPMI and visualized by fluorescence microscopy. Bar, 2 μm.

Mentions: The mdm17 mutant was isolated in a screen for novel alleles of mdm13, an uncharacterized gene that is required for normal mitochondrial inheritance and morphology. This screen involved crossing a haploid strain harboring the temperature-sensitive mdm13 lesion to a collection of temperature-sensitive strains and analyzing growth of the resulting diploids at the nonpermissive temperature (37°C). One diploid strain displayed temperature-sensitive growth, and analysis of its meiotic progeny indicated that one of two mutations conferring temperature-sensitive growth mapped to a genetic locus unlinked to mdm13. Therefore, rather than being an allele of mdm13, the new mutation defined a distinct gene. Analysis of cells harboring only the new mutation (after its genetic isolation from mdm13) by staining with the mitochondria-specific, vital dye DASPMI and fluorescence microscopy revealed defects in mitochondrial distribution and morphology after incubation at the nonpermissive temperature (Fig. 1). Complementation and allelism tests indicated that the new mutation was unlinked to previously characterized mdm mutations. Genetic analysis further demonstrated that the defects in growth at 37°C, mitochondrial distribution, and mitochondrial morphology were caused by a single nuclear mutation. This novel mutation was designated mdm17.


The yeast dynamin-like protein, Mgm1p, functions on the mitochondrial outer membrane to mediate mitochondrial inheritance.

Shepard KA, Yaffe MP - J. Cell Biol. (1999)

mdm17 cells are conditionally defective for mitochondrial inheritance and mitochondrial morphology.  Wild-type (MYY291) and mdm17 (MYY972) cells were  grown at 23°C in YPD-liquid medium and incubated at  (A) 23°C or (B) 37°C for 4 h. Mitochondria were stained  with DASPMI and visualized by fluorescence microscopy. Bar, 2 μm.
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Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2132935&req=5

Figure 1: mdm17 cells are conditionally defective for mitochondrial inheritance and mitochondrial morphology. Wild-type (MYY291) and mdm17 (MYY972) cells were grown at 23°C in YPD-liquid medium and incubated at (A) 23°C or (B) 37°C for 4 h. Mitochondria were stained with DASPMI and visualized by fluorescence microscopy. Bar, 2 μm.
Mentions: The mdm17 mutant was isolated in a screen for novel alleles of mdm13, an uncharacterized gene that is required for normal mitochondrial inheritance and morphology. This screen involved crossing a haploid strain harboring the temperature-sensitive mdm13 lesion to a collection of temperature-sensitive strains and analyzing growth of the resulting diploids at the nonpermissive temperature (37°C). One diploid strain displayed temperature-sensitive growth, and analysis of its meiotic progeny indicated that one of two mutations conferring temperature-sensitive growth mapped to a genetic locus unlinked to mdm13. Therefore, rather than being an allele of mdm13, the new mutation defined a distinct gene. Analysis of cells harboring only the new mutation (after its genetic isolation from mdm13) by staining with the mitochondria-specific, vital dye DASPMI and fluorescence microscopy revealed defects in mitochondrial distribution and morphology after incubation at the nonpermissive temperature (Fig. 1). Complementation and allelism tests indicated that the new mutation was unlinked to previously characterized mdm mutations. Genetic analysis further demonstrated that the defects in growth at 37°C, mitochondrial distribution, and mitochondrial morphology were caused by a single nuclear mutation. This novel mutation was designated mdm17.

Bottom Line: It also caused aberrant mitochondrial distribution and morphology when expressed at high levels in cells that also contained a wild-type copy of the gene.Mgm1p was localized to the mitochondrial outer membrane and fractionated as a component of a high molecular weight complex.These results indicate that Mgm1p is a mitochondrial inheritance and morphology component that functions on the mitochondrial surface.

View Article: PubMed Central - PubMed

Affiliation: Department of Biology, University of California, San Diego, La Jolla, California 92093-0347, USA.

ABSTRACT
The mdm17 mutation causes temperature-dependent defects in mitochondrial inheritance, mitochondrial morphology, and the maintenance of mitochondrial DNA in the yeast Saccharomyces cerevisiae. Defects in mitochondrial transmission to daughter buds and changes in mitochondrial morphology were apparent within 30 min after shifting cells to 37 degrees C, while loss of the mitochondrial genome occurred after 4-24 h at the elevated temperature. The mdm17 lesion mapped to MGM1, a gene encoding a dynamin-like GTPase previously implicated in mitochondrial genome maintenance, and the cloned MGM1 gene complements all of the mdm17 mutant phenotypes. Cells with an mgm1- mutation displayed aberrant mitochondrial inheritance and morphology. A version of mgm1 mutated in a conserved residue in the putative GTP-binding site was unable to complement any of the mutant defects. It also caused aberrant mitochondrial distribution and morphology when expressed at high levels in cells that also contained a wild-type copy of the gene. Mgm1p was localized to the mitochondrial outer membrane and fractionated as a component of a high molecular weight complex. These results indicate that Mgm1p is a mitochondrial inheritance and morphology component that functions on the mitochondrial surface.

Show MeSH
Related in: MedlinePlus