Very short patch repair protein (VSR) is an endonuclease from Escherichia coli and is a sequence specific mismatch endonuclease. It is responsible for the repair of T:G mismatches arising from the deamination of 5-methylcytosine. E. coli has three discovered systems for mismatched base pair recognition, all with different mechanisms. VSR initiates repair by hydrolysing the phosphate 5' of the mismatched T.
Defined by 4 residues: ASP:D-50 [auth A-51]THR:D-62 [auth A-63]HIS:D-68 [auth A-69]ASP:D-96 [auth A-97]