The deoxyribonucleic acid modification enzyme of bacteriophage P1. Purification and properties

Abstract

The bacteriophage P1 modification enzyme, assayed by the specific methylation of unmodified bacteriophage 82 DNA, has been purified 500-fold from a bacteriophage P1 lysogen of Escherichia coli. The enzyme catalyses the incorporation of approximately 20-24 methyl groups per bacteriophage 82 DNA molecule. The sole product of methylation is 6-methylaminopurine. Methylation of unmodified bacteriophage DNA confers protection against a challenge by purified bacteriophage P1 restriction enzyme. The pH optimum is 6.0-6.25: the apparent K(m) for S-adenosyl-l-methionine is 5x10(-6)m.