Methylation of adenine and cytosine in some strains of Fusobacterium nucleatum.

DNA from six strains of Fusobacterium nucleatum was examined for possible methylation of adenine or cytosine in the restriction site GATC. F. nucleatum DNA was digested with the restriction enzymes Sau3AI, DpnI and MboI, subjected to electrophoresis in agarose gels and Southern blotting. The blots were hybridized with a polymerase chain reaction (PCR)-amplified DNA probe. Both radioactive and non-radioactive labeling methods were used. Some strains of F. nucleatum were found to be dam methylated or dcm methylated in the sequence GATC; the adenine residue is methylated in strain ATCC 10953, while the cytosine residue is methylated in the strains F1 and F3. Strains F6, ATCC 25586 and Fev1 are probably not methylated in this nucleotide sequence.