Genome stability determinants in viable yeast: old new and surprises.
Forrest A Spencer (1), Cheryl D Warren (1), Karen Yuen (2), Ou Chen (1), Philip A Hieter (2)
(1) Institute of Genetic Medicine, Johns Hopkins University, 720 Rutland Ave, Baltimore, MD, 21205, USA;
(2) CMMT, Univ of British Columbia, 950 W 28th Ave, Rm 2026, Vancouver, BC V5Z 4H4 CANADA
Proteins and pathways that maintain genome structure have been identified in many genetic screens. However, traditional methods are not comprehensive, and more players remain to be found. To systematically identify genes important for genome stability, we have examined the haploid and diploid deletion mutant sets using 3 distinct marker loss assays. In one, we modified the SGA method to construct ade2oc deletion strains containing a SUP11-marked artificial disome to detect instability by colony sectoring. In another, MAT locus loss was followed by the appearance of a-like faker cells in MATalpha deletion strains. Third, diploid mater frequency was determined in homozygous diploid mutant strains. Together, these screens detected elevated rates of increased chromosome loss, nondisjunction, mitotic recombination, nonreciprocal rearrangement, and gene conversion. 310 genes (6.5% of nonessentials) that contribute to genome stability were identified. These assays exhibited differentiation in genes they identify, with only 10% shared among all 3. In the 310, annotations on 40% are consistent with known contributors to genome stability, 20% are unannotated, and 40% are annotated for functions not previously implicated, such as macromolecular modification and metabolic pathways. 134 of 310 genes exhibit homology to proteins predicted from human, mouse, fly, worm, and pombe genomes. Studies to determine the mechanisms distinguished by the 3 assays are underway.
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