Very short patch repair endonuclease (Vsr)

The Very short patch repair endonuclease (Vsr) is a specialized bacterial enzyme that plays a pivotal role in the Very Short Patch (VSP) repair pathway. Its primary biological function is to correct T:G mismatches that arise from the spontaneous hydrolytic deamination of 5-methylcytosine to thymine, a common occurrence at DNA cytosine methyltransferase (Dcm) recognition sites, typically 5'-CCWGG-3' (PMID: 22912483, 10612397). Vsr recognizes these mismatches and introduces a strand-specific nick 5' to the mismatched thymine, which then allows DNA polymerase I and DNA ligase to restore the original C:G base pair (PMID: 11557809). This mechanism is essential for maintaining genomic stability and preventing C-to-T transition mutations in various bacteria, including Escherichia coli and Neisseria gonorrhoeae (PMID: 30161155). While Vsr is not currently a target for clinical therapeutics, it is a subject of significant interest in the study of bacterial mutation rates, evolution, and the development of antibiotic resistance (PMID: 25877151). Structurally, Vsr belongs to a unique class of endonucleases that share a fold with type II restriction enzymes but utilize a distinct catalytic mechanism involving a critical histidine residue and metal-ion coordination (PMID: 10612397).

Other names

Vsr endonucleaseVsr mismatch endonucleaseVery short patch repair proteinV.EcoKDcm

The enzyme recognizes T:G mismatches within specific DNA sequences (typically 5'-CCWGG-3') and catalyzes a strand-specific nick 5' to the mismatched thymine to initiate repair.