title: Comparison of repair of methylated pyrimidines in poly(dT) by extracts from rat liver and Escherichia coli.
abstract: Partially purified preparations of O6-alkylguanine-DNA alkyltransferase from rat liver and E. coli were tested for their ability to repair O4-methylthymine in a methylated poly(dT) X poly(dA) substrate. The bacterial preparation readily carried out this reaction, but no loss of O4-methylthymine was obtained with the rat liver protein. These results indicate a significant difference in specificity between the mammalian and bacterial proteins which could have important consequences for carcinogenesis and mutagenesis by alkylating agents in mammalian cells.
mesh_terms: D000818:Animals; D004260:DNA Repair; D004926:Escherichia coli / Q000201:enzymology*; D006147:Guanine / Q000031:analogs & derivatives / Q000032:analysis; D008099:Liver / Q000201:enzymology*; D008745:Methylation; D008780:Methyltransferases / Q000302:isolation & purification / Q000378:metabolism*; D019853:O(6)-Methylguanine-DNA Methyltransferase; D011071:Poly T / Q000378:metabolism*; D011089:Polydeoxyribonucleotides / Q000378:metabolism*; D051381:Rats; D013941:Thymine / Q000031:analogs & derivatives / Q000032:analysis
chemical_list: D011089:Polydeoxyribonucleotides; D011071:Poly T; C021223:O-4-methylthymine; D006147:Guanine; C008449:O-(6)-methylguanine; D008780:Methyltransferases; D019853:O(6)-Methylguanine-DNA Methyltransferase; D013941:Thymine