Helicase Hmi1 stimulates the synthesis of concatemeric mitochondrial DNA molecules in yeast Saccharomyces cerevisiae |
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Authors: | Tiina Sedman Priit Jõers Silja Kuusk Juhan Sedman |
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Institution: | (1) Department of General and Microbial Biochemistry, University of Tartu, Vanemuise 46, Tartu 51014, Estonia |
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Abstract: | Hmi1p is a helicase in the yeast Saccharomyces cerevisiae required for maintenance of the wild-type mitochondrial genome. Disruption of the HMI1 ORF generates – and 0 cells. Here we demonstrate that, in – yeast strains, Hmi1p stimulates the synthesis of long concatemeric mitochondrial DNA molecules associated with a reduction in the number of nucleoids used for mitochondrial DNA packaging. Surprisingly, the ATPase negative mutants of Hmi1p can also stimulate the synthesis of long concatemeric – mitochondrial DNA molecules and support the maintenance of the wild-type mitochondrial genome, albeit with reduced efficiency. We show that, in the mutant hmi1–5 background, the wild-type mitochondrial DNA is fragmented; and we propose that, in hmi1 yeast cells, the loss of the wild-type mitochondrial genome is caused by this fragmentation of the mitochondrial DNA. |
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Keywords: | DNA replication Hypersuppressive strain –" target="_blank">gif" alt="rgr" align="MIDDLE" BORDER="0">– genome Mitochondrial nucleoid Mitochondrial RNA polymerase 2D gel analysis |
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