Mutational analysis of the 5'-OH oligonucleotide phosphate acceptor site of T4 polynucleotide kinase.

ABSTRACT: T4 polynucleotide kinase/phosphatase (Pnkp) exemplifies a family of bifunctional enzymes with 5'-kinase and 3'-phosphatase activities that function in nucleic acid repair. The N-terminal kinase domain belongs to the P-loop phosphotransferase superfamily. The kinase is distinguished by a tunnel-like active site with separate entrances on opposite sides of the protein for the NTP phosphate donor and a 5'-OH single-stranded oligonucleotide phosphate acceptor. Here, we probed by mutagenesis the roles of individual amino acids that comprise the acceptor binding site. We thereby identified Glu57 as an important residue, by virtue of its participation in a salt bridge network with two catalytic residues identified previously: Arg38, which binds the 3'-phosphate of the terminal 5'-OH nucleotide, a

SUBMITTER: Wang LK 

PROVIDER: S-EPMC2831316 | biostudies-literature | 2010 Mar

REPOSITORIES: biostudies-literature