This family of domains contain only a P-loop motif, that is characteristic of the AAA superfamily. Many of the proteins in this family are just short fragments so there is no Walker B motif.
This enzyme catalyses 5'-hydroxyl kinase, 3'-phosphatase and 2',3'-cyclic phosphodiesterase activities. These activities modify the ends of nicked tRNA generated by bacterial response to infection. These catalytic activities are dependent on magnesium as a cofactor. The kinase activity resides in an N-terminal domain, whilst the phosphatase activity resides in the C-terminal domain. T4 PNK also has the ability to overcome some bacterial suicide defence mechanisms. It is a member of a family of 5'-kinase/3'-phosphatases that mend broken strands in nucleic acids in conjunction with a RNA/DNA ligase. The kinase domain belongs to the adenylate kinase family whilst the phosphatase domain belongs to the L-2-haloacid dehalogenase.
Defined by 4 residues: LYS:A-15ASP:A-35ARG:A-126ASP:A-165