OVEREXPRESSION OF THE YEAST HAM1 GENE PREVENTS 6-N-HYDROXYLAMINOPURINE MUTAGENESIS IN ESCHERICHIA-COLI

The base analogue 6-N-hydroxylaminopurine (HAP) is a potent mutagen in a variety of prokaryotic and eukaryotic organisms. Mutations in the y east ham1 gene sender the cells hypersensitive to the mutagenic effect of HAP. We have found that this gene has homologues in a variety of o rganisms from bacteria to man. We have overexpressed yeast Ham1p in E. coli. We demonstrate that under conditions when this protein constitu tes approximately 30% of cellular protein, the host strain is protecte d both from toxic and mutagenic effects of HAP. This result indicates that sole Ham1p activity might be sufficient for destruction of HAP or its metabolites in bacterial cells.