A Gm6AG-binding protein from Vibrio cholerae.

Most known modification-dependent restriction endonucleases target 5-methylcytosine, only a few N6-methyladenine (6mA)-dependent restriction endonucleases have been well-characterized, and the majority of them recognize the G6mATC motif (e.g., DpnI, HHPV4I). Here, we report the identification of a novel 6mA-dependent DNA-binding protein from Vibrio cholerae, VchI, which specifically recognizes the G6mAG motif. VchI contains a winged helix (wH) domain that is homologous to the wH domain in DpnI. However, several key residues involved in 6mA recognition differ between VchI and DpnI, which may contribute to the discrepancy in their recognition specificities. These findings advance our understanding of prokaryotic 6mA modification diversity and the 6mA recognition mechanism of the wH domain, while simultaneously providing an innovative tool for epigenetic research.