This model describes the N-terminal domain of a group of mostly uncharacterised proteins, including 5-methylcytosine-specific restriction enzyme B (also known as MrcB) from E. coli. MrcB recognises N4- and C5-methylcytosine (and 5-hydroxy-methylcytosines) produced by a broad range of DNA methylases and appears to act against 5-methylcytosine preceded by a purine residue [1]. The N-terminal domain of MrcB has been shown to be a DNA-binding domain, and the crystal structure has been solved [2].

1: McrB: a prokaryotic protein specifically recognizing DNA containing modified cytosine residues. Kruger T, Wild C, Noyer-Weidner M; EMBO J. 1995;14:2661-2669. PMID:7781618

2: The recognition domain of the methyl-specific endonuclease McrBC flips out 5-methylcytosine. Sukackaite R, Grazulis S, Tamulaitis G, Siksnys V; Nucleic Acids Res. 2012;40:7552-7562. PMID:22570415