title: Induction of resistance to alkylating agents in E. coli: the ada+ gene product serves both as a regulatory protein and as an enzyme for repair of mutagenic damage.
abstract: The expression of several inducible enzymes for repair of alkylated DNA in Escherichia coli is controlled by the ada+ gene. This regulatory gene has been cloned into a multicopy plasmid and shown to code for a 37-kd protein. Antibodies raised against homogeneous O6-methylguanine-DNA methyltransferase (the main repair activity for mutagenic damage in alkylated DNA) were found to cross-react with this 37-kd protein. Cell extracts from several independently derived ada mutants contain variable amounts of an altered 37-kd protein after an inducing alkylation treatment. In addition, an 18-kd protein identical with the previously isolated O6-methyl-guanine-DNA methyltransferase has been identified as a product of the ada+ gene. The smaller polypeptide is derived from the 37-kd protein by proteolytic processing.
mesh_terms: D000477:Alkylating Agents / Q000633:toxicity*; D001426:Bacterial Proteins / Q000235:genetics*; D004260:DNA Repair; D004352:Drug Resistance, Microbial; D004926:Escherichia coli / Q000187:drug effects* / Q000235:genetics; D005796:Genes; D005798:Genes, Bacterial; D005809:Genes, Regulator; D008780:Methyltransferases / Q000235:genetics*; D009693:Nucleic Acid Hybridization; D019853:O(6)-Methylguanine-DNA Methyltransferase; D010641:Phenotype; D010957:Plasmids
chemical_list: D000477:Alkylating Agents; D001426:Bacterial Proteins; D008780:Methyltransferases; D019853:O(6)-Methylguanine-DNA Methyltransferase