This is the N-terminal domain found in modification-dependent restriction endonuclease proteins such as AspBHI, which can be found in Azoarcus sp. AspBHI is a homo-tetrameric protein that recognizes 5-methylcytosine in the double-strand DNA sequence context of (C/T) (C/G) (5mC) nucleotide (C/G) and cleaves the two strands at a fixed distance (N12/N16) 3 to the modified cytosine. The N-terminal domain is responsible for DNA-recognition and resembles an SRA-like 5-methylcytosine binding domain in structure and function [1].

1: Structure and mutagenesis of the DNA modification-dependent restriction endonuclease AspBHI. Horton JR, Nugent RL, Li A, Mabuchi MY, Fomenkov A, Cohen-Karni D, Griggs RM, Zhang X, Wilson GG, Zheng Y, Xu SY, Cheng X; Sci Rep. 2014;4:4246. PMID:24604015