INACTIVATION OF YME1, A MEMBER OF THE FTSH-SEC18-PAS1-CDC48 FAMILY OFPUTATIVE ATPASE-ENCODING GENES, CAUSES INCREASED ESCAPE OF DNA FROM MITOCHONDRIA IN SACCHAROMYCES-CEREVISIAE

The yeast nuclear gene YME1 was one of six genes recently identified i n a screen for mutations that elevate the rate at which DNA escapes fr om mitochondria and migrates to the nucleus. yme1 mutations, including a deletion, cause four known recessive phenotypes: an elevation in th e rate at which copies of TRP1 and ARS1, integrated into the mitochond rial genome, escape to the nucleus; a heat-sensitive respiratory-growt h defect; a cold-sensitive growth defect on rich glucose medium; and s ynthetic lethality in rho- (cytoplasmic petite) cells. The cloned YME1 gene complements all of these phenotypes. The gene product, Yme1p, is immunologically detectable as an 82-kDa protein present in mitochondr ia. Yme1p is a member of a family of homologous putative ATPases, incl uding Sec18p, Pas1p, Cdc48p, TBP-1, and the FtsH protein. Yme1p is mos t similar to the Escherichia coli FtsH protein, an essential protein i nvolved in septum formation during cell division. This observation sug gests the hypothesis that Yme1p may play a role in mitochondrial fusio n and/or division.