Isolation of Deoxyribonucleic Acid Methylase Mutants of Escherichia coli K-12

摘要: Fourteen deoxyribonucleic acid (DNA) and 10 ribonucleic (RNA) methylation mutants were isolated from Escherichia coli K-12 by examining the ability of nucleic acids prepared clones unselected mutagenized cells to accept methyl groups wild-type crude extract. Eleven DNA deficient in 5-methylcytosine (5-MeC) designated Dcm. Three N6-methyladenine (N6-MeA) Dam. Extracts tested for DNA-cytosine:S-adenosylmethionine DNA-adenine:S-adenosylmethionine methyltransferase activities. With one exception, all had reduced or absent activity. A representative Dcm mutation was located at 36 37 min a Dam 60-to 66-min region on genetic map. The no obvious associated phenotypic abnormality. defective their restrict λ. None mutations effect being lethal.