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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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Mgm1p is an integral membrane protein. Mitochondria  were isolated from wild-type (MYY290) cells and treated with  0.1 M sodium carbonate, 1 M NaCl, or buffer. Samples were separated into supernatant and pellet fractions by centrifugation at  150,000 g for 1 h, and equivalent amounts were subjected to SDS-PAGE and immunoblot analysis. Supernatant (S) and pellet (P)  fractions were analyzed with antibodies against Mgm1p (top) and  OM45, an integral protein of the mitochondrial outer membrane  (bottom).
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Figure 5: Mgm1p is an integral membrane protein. Mitochondria were isolated from wild-type (MYY290) cells and treated with 0.1 M sodium carbonate, 1 M NaCl, or buffer. Samples were separated into supernatant and pellet fractions by centrifugation at 150,000 g for 1 h, and equivalent amounts were subjected to SDS-PAGE and immunoblot analysis. Supernatant (S) and pellet (P) fractions were analyzed with antibodies against Mgm1p (top) and OM45, an integral protein of the mitochondrial outer membrane (bottom).

Mentions: To examine the nature of Mgm1p association with the outer membrane, isolated mitochondria were extracted with sodium chloride and with sodium carbonate. The latter treatment strips peripheral proteins but leaves integral proteins embedded in the membrane (Fujiki et al., 1982). Mgm1p was resistant to extraction with 1 M NaCl (Fig. 5), indicating that the protein was tightly associated with the membrane. After carbonate treatment, the 90-kD form of Mgm1p was recovered in the soluble fraction, while the 100-kD form remained associated with the membrane (Fig. 5). This result indicates that the full-length Mgm1p is an integral membrane protein. The behavior of the 90-kD fragment suggests that Mgm1p is embedded in the membrane via the putative membrane-spanning domain in the NH2 terminus, since both Mgm1p species are recognized by the antibody specific for the extreme COOH terminus.


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

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

Mgm1p is an integral membrane protein. Mitochondria  were isolated from wild-type (MYY290) cells and treated with  0.1 M sodium carbonate, 1 M NaCl, or buffer. Samples were separated into supernatant and pellet fractions by centrifugation at  150,000 g for 1 h, and equivalent amounts were subjected to SDS-PAGE and immunoblot analysis. Supernatant (S) and pellet (P)  fractions were analyzed with antibodies against Mgm1p (top) and  OM45, an integral protein of the mitochondrial outer membrane  (bottom).
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Related In: Results  -  Collection

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getmorefigures.php?uid=PMC2132935&req=5

Figure 5: Mgm1p is an integral membrane protein. Mitochondria were isolated from wild-type (MYY290) cells and treated with 0.1 M sodium carbonate, 1 M NaCl, or buffer. Samples were separated into supernatant and pellet fractions by centrifugation at 150,000 g for 1 h, and equivalent amounts were subjected to SDS-PAGE and immunoblot analysis. Supernatant (S) and pellet (P) fractions were analyzed with antibodies against Mgm1p (top) and OM45, an integral protein of the mitochondrial outer membrane (bottom).
Mentions: To examine the nature of Mgm1p association with the outer membrane, isolated mitochondria were extracted with sodium chloride and with sodium carbonate. The latter treatment strips peripheral proteins but leaves integral proteins embedded in the membrane (Fujiki et al., 1982). Mgm1p was resistant to extraction with 1 M NaCl (Fig. 5), indicating that the protein was tightly associated with the membrane. After carbonate treatment, the 90-kD form of Mgm1p was recovered in the soluble fraction, while the 100-kD form remained associated with the membrane (Fig. 5). This result indicates that the full-length Mgm1p is an integral membrane protein. The behavior of the 90-kD fragment suggests that Mgm1p is embedded in the membrane via the putative membrane-spanning domain in the NH2 terminus, since both Mgm1p species are recognized by the antibody specific for the extreme COOH terminus.

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