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© The Rockefeller University Press,
0021-9525/2001//401 $5.00
The Journal of Cell Biology, Volume 152, Number 2,
, 2001 401-410
Original Article |
Mmm1p, a Mitochondrial Outer Membrane Protein, Is Connected to Mitochondrial DNA (Mtdna) Nucleoids and Required for Mtdna Stability
rjensen{at}jhmi.edu
In the yeast Saccharomyces cerevisiae, mitochondria form a branched, tubular reticulum in the periphery of the cell. Mmm1p is required to maintain normal mitochondrial shape and in mmm1 mutants mitochondria form large, spherical organelles. To further explore Mmm1p function, we examined the localization of a Mmm1p–green fluorescent protein (GFP) fusion in living cells. We found that Mmm1p-GFP is located in small, punctate structures on the mitochondrial outer membrane, adjacent to a subset of matrix-localized mitochondrial DNA nucleoids. We also found that the temperature-sensitive mmm1-1 mutant was defective in transmission of mitochondrial DNA to daughter cells immediately after the shift to restrictive temperature. Normal mitochondrial nucleoid structure also collapsed at the nonpermissive temperature with similar kinetics. Moreover, we found that mitochondrial inner membrane structure is dramatically disorganized in mmm1 disruption strains. We propose that Mmm1p is part of a connection between the mitochondrial outer and inner membranes, anchoring mitochondrial DNA nucleoids in the matrix.
Key Words: mitochondria MMM1 cristae nucleoids mitochondrial DNA
© 2001 The Rockefeller University Press
The online version of this article contains supplemental material.Dr. Srinivasan's present address is 454 Corporation, 10865 Altman Row, Suite 100, San Diego, CA 92121.
Abbreviations used in this paper: 3-D, three dimensional; DIC, differential interference contrast; GFP, green fluorescent protein; HA, hemagglutinin; mtDNA, mitochondrial DNA.
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