DNA methylase Hha1PDB ID: 1MHT
Hha1 adds methyl groups to DNA in bacterial cells, as part of the restriction/modification system that protects the cell from viruses.
HhaI methyltransferase flips its target base out of the DNA helix.
Klimasauskas, S., Kumar, S., Roberts, R.J., Cheng, X.
Journal: (1994) Cell(Cambridge,Mass.) 76: 357-369