|Maintenance of Mitochondrial Morphology is Linked to Maintenance of the Mitochondrial Genome in Saccharomyces cerevisiae.|
Hanekamp T, Thorsness MK, Rebbapragada I, Fisher EM, Seebart C, Darland MR, Coxbill JA, Updike DL, Thorsness PE
Category: mitochondria-biogenesis, mitochondrial DNA, mitochondrial nucleoids ¤ Added: Dec 10, 2002 ¤ Rating: ◊◊
In the yeast Saccharomyces cerevisiae, certain mutant alleles of yme4, yme6, and mdm10 cause an increased rate of mitochondrial DNA migration to the nucleus, carbon-source dependent alterations in mitochondrial morphology, and increased rates of mitochondrial DNA loss. While single mutants grow on media requiring mitochondrial respiration, any pair-wise combination of these mutations cause a respiratory-dependent growth defect. This double mutant phenotype allowed cloning of YME6, which is identical to MMM1 and encodes an outer mitochondrial membrane protein essential for maintaining normal mitochondrial morphology. Yeast strains bearing null mutations of MMM1 have altered mitochondrial morphology, a slow growth-rate on all carbon sources, and quantitatively lack mitochondrial DNA. Extragenic suppressors of MMM1 deletion mutants partially restore mitochondrial morphology to the wild-type state, and have a corresponding increase in growth rate and mitochondrial DNA stability. A dominant suppressor also suppresses the phenotypes caused by a point mutation in MMM1, as well as by specific mutations in YME4 and MDM10.