Chromium sensitive mutants of the yeast Saccharomyces cerevisiae

Ten mutants of Saccharomyces cerevisiae sensitive to CrO3 were obtained and genetically analyzed. All of them were recessive. Segregation of the sensitivity after crossing them with a wild type strain indicated that the sensitivity of some mutants was determined by single mutations and that of others was caused by multiple mutations. Among 6 mutations found in mutants having single mutations responsible for the sensitivity, 6 loci were distinguished by complementation. One of them was identified as LYS7, the gene previously known as the structure gene for homocitric dehydrase, in terms of co-segregation and co-reversion of chromium sensitivity and lysine dependency which did not complement an authentic lys7 mutation.