Characterization of Two Mutant Strains of Saccharomyces cerevisiae Deficient in Coproporphyrinogen III Oxidase Activity

Abstract

Two new hemedeficient mutants of S. cerevisiae were isolated on the basis of their catalase deficiency. Mutant H11 accumulated and excreted coproporphyrin III and was completely deficient in heme; the cell-free extract had no coproporphyrinogen oxidase activity. Mutant H12 accumulated uroporphyrin to coproporphyrin III and excreted coproporphyrin III and contained a small amount of heme; the cell-free extract had a residual coproporphyrinogen oxidase activity. The 2 mutations were allelic and the mutant phenotypes were under the control of a single, recessive nuclear gene.