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 deduc ed sequence has significant homology with DNA (N-6-adenine) methyltran sferases. T. pallidum Dam can be assigned to group a DNA amino methylt ransferases based on the order of nine conserved motifs that are prese nt in the protein. Digests of T. pallidum chromosomal DNA performed wi th isoschizomer restriction endonucleases (Sau3AI, DpnI, and MboI) con firmed the presence of methylated adenine residues in GATC sequences ( Dam(+) phenotype).