EC Number   |
General Information |
Reference |
|---|
   2.7.1.78 | physiological function |
bifunctional polynucleotide kinase/phosphatase contains both DNA 5'-kinase and 3'-phosphatase activities required for restoration of 3'-hydroxyls and 5'-phosphates needed to seal the broken DNA. Cellular DNA is constantly assaulted by ionizing radiation and reactive oxygen species. This damage, along with the products of some DNA repair enzymes, may contain 5' hydroxyls or 3' phosphates. These are converted by PNK to 5' phosphates and 3' hydroxyls, which are required for DNA polymerases and DNA ligases to complete repair of the damaged DNA. Productive engagement of a 3'-phosphate terminus may block access of a 5'-hydroxyl to the kinase active site |
723644 |
| 2.7.1.78 | physiological function |
degradation of RegB-cleaved mRNAs depends on a functional T4 polynucleotide kinase/phosphatase. PNK controls the decay of early transcripts predominantly from their 5'-termini. The 5'-OH produced by RegB cleavage is phosphorylated by the kinase activity of PNK. When the 5'-OH RNA end generated by RegB is not phosphorylated by PNK, the attack by RNases E and G is blocked or decreased over a distance of about 300 nt from the RegB site. But after PNK has modified the 5'-terminus and RNase G (or E) has cut at secondary sites, the new 5'-monophosphorylated RNA ends can presumably activate RNases E and G in cascade. The PNK-dependent pathway of degradation becomes effective 5 min postinfectio. The T4 PNK also has a role during normal phage development |
723662 |
| 2.7.1.78 | malfunction |
depletion of Nol9 leads to a severe impairment of ribosome biogenesis. Upon Nol9 knockdown, specific maturation defect at the 5' end of the predominant 5.8S short-form rRNA (5.8SS) occur, possibly due to the Nol9 requirement for 5'>3' exonucleolytic trimming |
722115 |
| 2.7.1.78 | malfunction |
knockdown of polynucleotide kinase and aprataxin-like forkhead-associated using siRNA reduces rejoining of two incompatible I-SceI-generated DNA ends by 50% |
722727 |
| 2.7.1.78 | physiological function |
mice with PNKP inactivation in neural progenitors manifest neurodevelopmental abnormalities and postnatal death. The phenotype involves defective base excision repair and nonhomologous end-joining. Mice homozygous for the T424GfsX48 frame-shift allele are lethal embryonically, and attenuated PNKP levels akin to microcephaly with seizures syndrome show general neurodevelopmental defects. Directed postnatal neural inactivation of PNKP affects specific subpopulations including oligodendrocytes |
750414 |
| 2.7.1.78 | more |
molecular architecture of the enzyme, overview. The mammalian enzyme preferentially phosphorylates 5'-hydroxyl termini within nicked, gapped or double-strand breaks with single-stranded 3'-overhanging ends, whereas single-stranded 5'-termini or blunt double-stranded ends are phosphorylated less efficiently. The selective recognition of the larger, double-stranded DNA substrates is effected by a broad DNA recognition groove composed of two distinct positively charged surfaces. Mechanisms of single-strand break and double-strand break repairs, and of base excision repair, overview |
716975 |
| 2.7.1.78 | more |
molecular architecture of the enzyme, overview. The mammalian enzyme preferentially phosphorylates 5'-hydroxyl termini within nicked, gapped or DSBs with single-stranded 3' overhanging ends, whereas single-stranded 5'-termini or blunt double-stranded ends are phosphorylated less efficiently. The selective recognition of the larger, double-stranded DNA substrates is effected by a broad DNA recognition groove composed of two distinct positively charged surfaces. Mechanisms of single-strand break and double-strand break repairs, and base excision repair, overview |
716975 |
| 2.7.1.78 | more |
molecular architecture of the enzyme, overview. The phage PNK DNA binding cleft forms a narrow channel leading to the conserved catalytic aspartic acid residue that accommodates single-stranded, but not double-stranded, substrates. Mechanisms of single-strand break and double-strand break repairs, overview |
716975 |
| 2.7.1.78 | malfunction |
mutations lead to a loss of enzyme interaction with the tRNA splicing endonuclease complex, largely reduced pretRNA cleavage activity, and accumulation of linear tRNA introns. The affected individuals develop severe motor-sensory defects, cortical dysgenesis, and microcephaly |
729562 |
| 2.7.1.78 | more |
PNK domain architecture, overview |
723644 |
