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

Name: Thorsness, Peter E.
Mailing Address: Molecular Biology, University of Wyoming, University Station, Laramie, WY 82071-3944, U.S.A.
Email Address: thorsnes@uwyo.edu
Phone & FAX numbers: 307-766-2038 & 307-766-5098

#038

Multiple mechanisms for the escape of DNA from mitochondria to the nucleus.
Peter E. Thorsness, Theodor Hanekamp, Indrani Rebbapragada, Karen H. White, Dustin L. Updike, Peter A. Jordan, Kelly A. Schalk
Molecular Biology, University of Wyoming, University Station, Laramie, WY 82071-3944, U.S.A.

The transfer of nucleic acids from organelles to the nucleus has influenced the evolution of eucaryotes, the structure of chromosomes, and cellular pathology. In S. cerevisiae, mutations in genes involved in at least three aspects of mitochondrial biology can influence the rate of mtDNA escape to the nucleus. First, inactivation of Yme1p, a metal-dependant protease located in the inner mitochondrial membrane, leads to damaged mitochondrial compartments that are turned over by the vacuole with the subsequent release of mtDNA. Second, mutations in MMM1 and YME4 lead to alterations of mitochondrial morphology and an associated increase in the escape of mtDNA. Mmm1p is necessary for proper maintenance of mitochondrial morphology, apparently via association with the actin cytoskeleton. Suppressors of mmm1 deletions that restore to various degrees wild type mitochondrial morphology also suppress the mtDNA loss phenotype. Third, genes involved in packaging mtDNA into membrane associated nucleoids can also influence the rate of mtDNA escape. Yme2p is found in the inner mitochondrial membrane and co-purifies with both mtDNA and the nucleoid associated protein Abf2p. YME2 deletion strains display only a high rate of mtDNA escape whereas yme2-4 strains have several severe growth defects and no escape of mtDNA. Based on the genetic, physical, and sequence properties of Yme2p, we propose that this protein is involved in several mtDNA transactions.

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