Figure 4.

OGG1 expression suppresses the frequency of mitochondrial mutants. Yeast and human OGG1 cDNA was cloned under the control of the constitutive ADH promoter as described in Materials and Methods. Both wild-type (WT) and ogg1 null mutant (ogg1) were transformed and the frequency of mitochondrial mutants was determined by the colony color assay (see Materials and Methods). (A) Suppression of spontaneous mitochondrial mutants in wild-type and ogg1 null mutant cells expressing either yeast or human OGG1. (B) Suppression of adriamycin-induced mitochondrial mutants in wild-type cells expressing either yeast or human OGG1 (yOGG1 and hOGG1, respectively). Adriamycin concentration was 50 µg/ml. The number of independent cultures used in the study is shown in parentheses in (A).