DNA (cytosine-5-)-methyltransferase (HhaI)
M-CSA #293
Methyl transferase (MTase) M. Hhal is an m5C-MTase that forms part of a type II restriction-modification system from Haemophilus haemolyticus. The enzyme recognises the specific tetranucleotide sequence, 5-GCGC-3. DNA methylation is found in diverse organisms ranging from bacteria to mammals and plants. Cytosine-5-methyltransferases (m5CMTases) are involved in a variety of biological processes in prokaryotes and eukaryotes by catalysing the transfer of a methyl group from S-adenosyl- L-methionine (AdoMet) to the C5 position of cytosine. MTases exist as a component of restriction and modification systems in bacteria.
Defined by 4 residues: CYS:C-81 [auth A-81]GLU:C-119 [auth A-119]ARG:C-163 [auth A-163]ARG:C-165 [auth A-165]