This domain is found at the N-terminal end of Restriction endonuclease PvuRts1 I from Proteus vulgaris and similar bacterial sequences. PvuRts1I a modification-dependent endonuclease with high selectivity for 5-hydroxymethylcytosine, an epigenetic marker that is crucial for multiple biological processes, over 5-methylcytosine and cytosine. This protein is organised into a nuclease domain (this entry) and a C-terminal SRA domain (Pfam:PF18491). This domain adopts a typical three- layered alpha-beta-alpha sandwich configuration, with a central five-stranded beta-sheet surrounded by three alpha-helices on one side and one alpha-helix on the other side [1-3].

1: Structural basis for the substrate selectivity of PvuRts1I, a 5-hydroxymethylcytosine DNA restriction endonuclease. Shao C, Wang C, Zang J; Acta Crystallogr D Biol Crystallogr. 2014;70:2477-2486. PMID:25195760

2: Crystal structure of the 5hmC specific endonuclease PvuRts1I. Kazrani AA, Kowalska M, Czapinska H, Bochtler M; Nucleic Acids Res. 2014;42:5929-5936. PMID:24634440

3: Structure of 5-hydroxymethylcytosine-specific restriction enzyme, AbaSI, in complex with DNA. Horton JR, Borgaro JG, Griggs RM, Quimby A, Guan S, Zhang X, Wilson GG, Zheng Y, Zhu Z, Cheng X; Nucleic Acids Res. 2014;42:7947-7959. PMID:24895434