Identification and characterization of a Treponema pallidum subsp. pallidum gene encoding a DNA adenine methyltransferase

The nucleotide sequence of a DNA adenine methyltransferase gene (dam) from Treponema pallidum has been determined. Southern blot analysis of T. pallidum chromosomal DNA indicated that this gene is present as a single copy. The dam gene encodes a 303 amino acid protein whose deduced sequence has significant homology with DNA (N-6-adenine) methyltransferases. T. pallidum Dam can be assigned to group a DNA amino methyltransferases based on the order of nine conserved motifs that are present in the protein. Digests of T. pallidum chromosomal DNA performed with isoschizomer restriction endonucleases (Sau3AI, DpnI, and MboI) confirmed the presence of methylated adenine residues in GATC sequences (Dam(+) phenotype).