Yeast Genetics and Molecular Biology 2000
University of Washington
Seattle, Washington USA
July 2000

Name: Aiken Hobbs, Alyson E.
Mailing Address: Cell Biology & Anatomy, Johns Hopkins University SOM, 725 N. Wolfe Street, Baltimore, MD 21044, USA
Email Address: aaiken@jhmi.edu
Phone & FAX numbers: 410-955-2494 & 410-955-4129

#039

Mmm1p plays a role in mitochondrial shape and mtDNA stability.
Alyson E. Aiken Hobbs (1), J. Micheal McCaffery (2), Robert E. Jensen (1)
(1) Cell Biology & Anatomy, Johns Hopkins University SOM, 725 N. Wolfe Street, Baltimore, MD 21044, USA; (2) Department of Biology, Johns Hopkins University, 3400 North Charles Street, Baltimore, MD 21218

In the yeast Saccharomyces cerevisiae, mitochondria form a branched, tubular reticulum in the periphery of the cell. Mmm1p, a mitochondrial outer membrane protein, is required for the maintenance of mitochondrial shape, and cells disrupted for MMM1 contain 1-5 large, spherical mitochondria. mmm1 mutants are also defective for transmission of mitochondria to daughter cells and rapidly lose mitochondrial DNA (mtDNA). To further probe the function of Mmm1p, we asked if Mmm1p associates with other proteins. Initial studies show that Mmm1p is present in a ~ 200 kDa detergent-stable complex. We also examined the sub-cellular location of Mmm1p using the green fluorescent protein (GFP). We find that a Mmm1-GFP fusion protein is located in small, discrete patches on the mitochondria surface, with ~ 7-10 patches per cell. This punctate localization of Mmm1p was confirmed by immuno-electron microscopy. Strikingly, we find that Mmm1-GFP co-localizes with a subset of mtDNA nucleoids. Our results raise the possibility that Mmm1p is part of a large structure linking the mtDNA and the inner and outer mitochondrial membranes. Studies to determine the role of the Mmm1p-containing complex are in progress.

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