SUMO Modification of Mitochondrial Protein Mgm101p.
Leah Jablonski, Anat Kohn, Elaine Sia
Biology, University of Rochester, 334 Hutchison Hall, Rochester, NY, 14127, USA
The stability of mitochondrial DNA (mtDNA) is essential for the normal function of eukaryotic cells. Instability of mtDNA has been implicated in several types of cancers and hereditary diseases, as well as the natural aging process. In the yeast Saccharomyces cerevisiae, mtDNA is packaged into nucleoprotein complexes called nucleoids. Mgm101p, a small protein encoded in the nucleus and imported into the mitochondria, is a component of the nucleiod. Loss of MGM101 leads to complete loss of mtDNA within twelve hours. Our data suggests that Mgm101p is modified by the ubiquitin-like modifying protein SUMO. We have observed a two-hybrid interaction between the SUMO protein Smt3p and Mmg101p. We have also constructed an Mgm101p mutant that no longer interacts with Smt3p. This mutant appears to have a temperature sensitive defect in respiration. These data suggests that Mgm101p is sumoylated, and that this modification is important for the mitochondrial function of Mgm101p.
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