Homologues of the Escherichia coli Eco57I restriction-modification methylase are found in several phylogenetically diverse bacteria. The structure of TaqI has been solved [1].

1: Cloning and sequence analysis of the genes coding for Eco57I type IV restriction-modification enzymes. Janulaitis A, Vaisvila R, Timinskas A, Klimasauskas S, Butkus V; Nucleic Acids Res 1992;20:6051-6056. PMID:1334261

2: Differential binding of S-adenosylmethionine S-adenosylhomocysteine and Sinefungin to the adenine-specific DNA methyltransferase M.TaqI. Schluckebier G, Kozak M, Bleimling N, Weinhold E, Saenger W; J Mol Biol. 1997;265:56-67. PMID:8995524