Molecular phylogenetics of DNA 5mC-methyltransferases.

We have identified a total of 88 members of the DNA-(cytosine-5) methyltransferase (5mC MTase) family whose sequences have been deposited in the databases. The results of a comparison of these sequences is presented in the form of an alignment-based phylogenetic tree and sequence logos for 10 conserved motifs. Phylogenetic analysis showed that members of the family aggregate into subfamilies which are usually consistent with their target specificity. However, it was also shown that similar target specificity does not necessarily imply close homology of the catalytic domain of MTases, which strongly supports the hypothesis that target recognition evolved independently of catalytic properties. This analysis also indicate that the 5mC MTase was present in the cenancestor (last common ancestor) of eubacteria, archaebacteria, and eukaryotes. The phylogeny of the 5mC MTases catalytic domain provides the basis for establishing the patterns of evolutionary change that characterize this family of proteins with conserved structural core and variable and mobile modules not directly involved in formation of the active site.