Structural highlights
Function
[KIPN_BPT4] Acts as a 5'-hydroxyl kinase, a 3'-phosphatase and a 2',3'-cyclic phosphodiesterase. Catalyzes the transfer of the terminal phosphate of ATP to the 5'-hydroxyl termini of ribo- and deoxyribonucleotides. In the presence of ADP the enzyme also catalyzes an exchange reaction. In the exchange reaction, an excess ADP causes the enzyme to transfer the 5' terminal phosphate from phosphorylated DNA to ADP. These activities modify the ends of nicked tRNA generated by a bacterial response to infection and facilitate repair by T4 RNA ligase.
Evolutionary Conservation
Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf.
Publication Abstract from PubMed
T4 polynucleotide kinase (Pnk), in addition to being an invaluable research tool, exemplifies a family of bifunctional enzymes with 5'-kinase and 3'-phosphatase activities that play key roles in RNA and DNA repair. T4 Pnk is a homotetramer composed of a C-terminal phosphatase domain and an N-terminal kinase domain. The 2.0 A crystal structure of the isolated kinase domain highlights a tunnel-like active site through the heart of the enzyme, with an entrance on the 5' OH acceptor side that can accommodate a single-stranded polynucleotide. The active site is composed of essential side chains that coordinate the beta phosphate of the NTP donor and the 3' phosphate of the 5' OH acceptor, plus a putative general acid that activates the 5' OH. The structure rationalizes the different specificities of T4 and eukaryotic Pnk and suggests a model for the assembly of the tetramer.
Structure and mechanism of T4 polynucleotide kinase: an RNA repair enzyme.,Wang LK, Lima CD, Shuman S EMBO J. 2002 Jul 15;21(14):3873-80. PMID:12110598[1]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
References
- ↑ Wang LK, Lima CD, Shuman S. Structure and mechanism of T4 polynucleotide kinase: an RNA repair enzyme. EMBO J. 2002 Jul 15;21(14):3873-80. PMID:12110598 doi:10.1093/emboj/cdf397
