Dendrogram of all available
sequences of N4 and N6 MTases of the α group.
The sequences compared consisted of the N- and C-termini, with the central TRD
removed. The TRD was liberally defined as the block corresponding to
residues 77 through 172 according to M.DpnII coordinates
(15). The branches of all N6mA
MTases are some hue of red and of all N4mC MTase some hue of blue.
Thin lines indicate that the target sequence of the enzyme has not
been established by biochemical criteria. Besides those sequences
listed in Table 1, the following were found through the indicated
accession nos: M.AvaI (CAA66984), M.BsoBI (CAA66933),
M.CviAII (S27901), M.CviBI (Q01511),
M.EcDam (P00475), M.EcoRV (P04393),
M.EcoT4Dam (X17641), M.FokI (P14871),
M.MboIA (P34720), M.MvaI (P14244),
M.NcoI (AAC23514), M.NlaIII, M.PspGI (AAC67523), M.SphI (AAB40377)
and M.TpaI (AAB82782). M.FokI
and M.StsI consist of two separable MTases that
are fused as a single polypeptide. The N-terminal portions (M.FokIa and M.StsIa) recognize one
asymmetric target and the C-terminal portions (M.FokIb
and M.StsIb) recognize the other.