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The RIR motif in the scaffold protein XRCC1 mediates a low-affinity interaction with polynucleotide kinase/phosphatase (PNKP) during DNA single-strand break repair

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posted on 2023-06-09, 07:55 authored by Claire Breslin, Rajam S Mani, Mesfin Fanta, Nicolas Hoch, Michael Weinfield, Keith CaldecottKeith Caldecott
The scaffold protein X-ray repair cross-complementing 1 (XRCC1)interacts with multiple enzymes involved in DNA base excision repair and single-strand break repair(SSBR) and is important for genetic integrity and normal neurological function. One of the most important interactions of XRCC1 is that with polynucleotide kinase/phosphatase(PNKP), a dual-function DNA kinase/phosphatase that processes damaged DNA termini and that, if mutated, results in ataxia with oculomotor apraxia 4 (AOA4) and microcephaly with early-onset seizures and developmental delay(MCSZ). XRCC1 and PNKP interact via a high-affinity phosphorylationdependent interaction site in XRCC1 and a fork-head associated domain in PNKP. Here, we identified using biochemical and biophysical approaches a second PNKP interaction site in XRCC1 that binds PNKP with lower affinity and independently of XRCC1 phosphorylation. However, this interaction nevertheless stimulated PNKP activity and promoted SSBR and cell survival. The low-affinity interaction site required the highly conserved REV1-interacting (RIR) motif in XRCC1 and included three critical and evolutionarily invariant phenylalanine residues. We propose a bipartite interaction model in which the previously identified highaffinity interaction acts as a molecular tether, holding XRCC1 and PNKP together and thereby promoting the low-affinity interaction identified here, which then stimulates PNKP directly.

Funding

Cellular and Pathological Responses to Chromosome DNA Single-Strand Breaks; G2053; MRC-MEDICAL RESEARCH COUNCIL; MR/P010121/1

Chromosomal Single-strand break Repair: Mechanisms & Degenerative Disease; G0830; MRC-MEDICAL RESEARCH COUNCIL; MR/J006750/1

History

Publication status

  • Published

File Version

  • Published version

Journal

Journal of Biological Chemistry

ISSN

1083-351X

Publisher

American Society for Biochemistry and Molecular Biology

Volume

292

Page range

16024-16031

Department affiliated with

  • Sussex Centre for Genome Damage Stability Publications

Research groups affiliated with

  • Genome Damage and Stability Centre Publications

Full text available

  • Yes

Peer reviewed?

  • Yes

Legacy Posted Date

2017-09-14

First Open Access (FOA) Date

2017-10-06

First Compliant Deposit (FCD) Date

2017-09-14

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