MGM101, A NUCLEAR GENE INVOLVED IN MAINTENANCE OF THE MITOCHONDRIAL GENOME IN SACCHAROMYCES-CEREVISIAE

A nuclear mutation, mgm101, results in temperature sensitive loss of m itochondrial DNA (mtDNA) in the yeast Saccharomyces cerevisiae. The co rresponding gene, MGM101, was isolated from a genomic DNA library by c omplementation. Sequence analysis shows that MGM101 encodes a positive ly charged protein of 269 amino acids with a calculated molecular weig ht of 30 kDa. This analysis also reveals that MGM101 is adjacent to th e ribosomal protein gene RPS7A on chromosome X and hybridization indic ates it occurs in single copy. Creation of a null mutant by targeted d isruption showed that the gene has no essential cellular function, asi de from its participation in mitochondrial genome maintenance. As no c ounterpart has been identified in databases it is a novel protein whos e role has yet to be determined. Expression of MGM101 is low on glucos e medium but on galactose there is a two-fold increase in the level of the transcript.