DNA methylase activities in aNeisseria gonorrhoeaeextract

Abstract

Resistance of Neisseria gonorrhoeae DNA to cleavage by various restriction endonucleases suggests the existence of modification enzymes which protect the corresponding recognition sequences. We indeed found methylase activities in N. gonorrhoeae extracts. These activities lead to the methylation of adenine and cytosine residues in bacteriophage λ DNA and DNA from an Escherichia coli Dam− strain. They also result in partial protection of λ DNA to cleavage by the restriction endonucleases HaeII, HaeIII, BamHI and, SacII.