Recombinant Human Bifunctional polynucleotide phosphatase/kinase (PNKP)

1. Despite presence of an alternative 3'-phosphatase, loss of PNKP significantly sensitizes cells to 3'-phosphate-terminated DSBs, due to a 3'-dephosphorylation defect. PMID: 29807321
2. PNKP mutation in two siblings is associated with progressive ataxia, abnormal saccades, sensorimotor neuropathy and dystonia consistent with ataxia with oculomotor apraxia disorders. PMID: 28552035
3. we have identified a mutation in PNKP, leading to a phenotype of microcephaly with primordial dwarfism. PMID: 27232581
4. XRCC1 and PNKP interact via a high-affinity phosphorylation-dependent interaction site in XRCC1 and a forkhead-associated domain in PNKP. Data suggest a second PNKP interaction site in XRCC1 that binds PNKP with lower affinity and independently of XRCC1 phosphorylation. (XRCC1 = X-ray repair cross complementing protein 1; PNKP = polynucleotide kinase 3'-phosphatase) PMID: 28821613
5. In a recombinant PNKP-XRCC4-LigIV complex, stable binding of PNKP requires XRCC4 phosphorylation. Only one PNKP protomer binds per XRCC4 dimer. Both the PNKP FHA and catalytic domains contact the XRCC4 coiled-coil and LigIV BRCT repeats. A surface on the PNKP phosphatase domain may contact XRCC4-LigIV. A mutation on this surface (E326K) impairs PNKP recruitment to damaged DNA and causes microcephaly with seizures. PMID: 28453785
6. Mutations in TDP1 and APTX have been linked to Spinocerebellar ataxia with axonal neuropathy (SCAN1) and Ataxia-ocular motor apraxia 1 (AOA1), respectively, while mutations in PNKP are considered to be responsible for Microcephaly with seizures (MCSZ) and Ataxia-ocular motor apraxia 4 (AOA4). PMID: 27470939
7. the role for PNKP in maintaining brain function and how perturbation in its activity can account for the varied pathology of neurodegeneration or microcephaly present in microcephaly with seizures and ataxia with oculomotor apraxia 4 respectively. PMID: 27125728
8. In 11 Portuguese patients, PNKP mutations cause ataxia with oculomotor apraxia type 4. PMID: 26970421
9. Here we report that purified wild-type (WT) ATXN3 stimulates, and by contrast the mutant form specifically inhibits, PNKP's 3' phosphatase activity in vitro. ATXN3-deficient cells also show decreased PNKP activity PMID: 25633985
10. We now report that the mutant ATXN3 protein interacts with and inactivates PNKP (polynucleotide kinase 3'-phosphatase), an essential DNA strand break repair enzyme PMID: 25590633
11. We identified homozygous or compound-heterozygous PNKP mutations in eight of the nine Portuguese families we studied, suggesting that, in Portugal, mutations in PNKP are the most frequent cause of ataxia with oculomotor apraxia. PMID: 25728773
12. we show that modest inhibition of PNKP in a PTEN knockout background enhances cellular radiosensitivity, suggesting that such a "synthetic sickness" approach involving the combination of PNKP inhibition with radiotherapy PMID: 23883586
13. Mutations in PNKP have previously been associated with a syndrome of microcephaly, seizures and developmental delay (MIM 613402), and is now associated with a neurodegenerative disorder. PMID: 23224214
14. the interaction between PNKP and XRCC1 has roles in the retention of XRCC1 at DNA damage sites and in DNA alkylation damage repair PMID: 22992732
15. The data suggest that all four known mutations associated with microcephaly, seizures and developmental delay reduce the cellular stability and level of PNKP protein, with three mutations likely ablating cellular DNA 5'-kinase activity and all of the mutations greatly reducing cellular DNA 3'-phosphatase activity. PMID: 22508754
16. the critical role of NEIL2 and PNKP in maintenance of the mammalian mitochondrial genome. PMID: 22130663
17. PNKP distorts target DNA structures to access damaged substrate DNA ends, thus providing a molecular mechanism for the involvement of PNKP in the repair of both single- and double-strand breaks. PMID: 22171004
18. Results reveal that ionizing radiation-induced phosphorylation of PNKP by ATM and DNA-PK regulates PNKP function at DNA double strand breaks. PMID: 21824916
19. Studies indicate that PNKP serves a crucial role in the repair of DNA strand breaks through interactions with other DNA repair proteins, notably XRCC1 and XRCC4. PMID: 21353781
20. CK2-mediated phosphorylation of XRCC4 can have different effects on PNKP activity. PMID: 20852255
21. The neurological abnormalities in individuals with microcephaly, early onset, intractable seizures and develomental delays may reflect a role for PNKP in several DNA repair pathways. PMID: 20118933
22. Involvement of human polynucleotide kinase in double-strand break repair by non-homologous end joining PMID: 12032095
23. First direct physical evidence for ternary complex formation involving a polynucleotide kinase, AMP-PNP, and an oligonucleotide, supports a reaction mechanism in which ATP and DNA bind simultaneously to the enzyme. PMID: 14556639
24. Data show that polynucleotide kinase is associated with the PARP-1-dependent end-joining pathway, and show functional parallels between the PARP-1 and DNA-PK-dependent end-joining processes. PMID: 16364363
25. polynucleotide kinase participates in repair of DNA double-strand breaks by nonhomologous end joining but not homologous recombination PMID: 17638872
26. XRCC1 enhances the capacity of hPNK to discriminate between strand breaks with 5'-OH termini and those with 5'-phosphate termini; and XRCC1 stimulates hPNK activity by displacing hPNK from the phosphorylated DNA product PMID: 17650498
27. The PNKP T5644G variant does not seem to be involved in adenoma recurrence in the Polyp Prevention Trial. PMID: 18414202
28. the FHA domain of PNK binds specifically, and with high affinity to a multiply phosphorylated motif in XRCC1 containing a pSer-pThr dipeptide, and forms a 2:1 PNK:XRCC1 complex. PMID: 19155274

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HGNC: 9154

OMIM: 605610

KEGG: hsa:11284

STRING: 9606.ENSP00000323511

UniGene: Hs.78016