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

Breslin, Claire, Mani, Rajam S, Fanta, Mesfin, Hoch, Nicolas, Weinfield, Michael and Caldecott, Keith W (2017) The RIR motif in the scaffold protein XRCC1 mediates a low-affinity interaction with polynucleotide kinase/phosphatase (PNKP) during DNA single-strand break repair. Journal of Biological Chemistry, 292. pp. 16024-16031. ISSN 1083-351X

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Abstract

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.

Item Type: Article
Schools and Departments: School of Life Sciences > Sussex Centre for Genome Damage and Stability
Research Centres and Groups: Genome Damage and Stability Centre
Depositing User: Sarah Frances
Date Deposited: 14 Sep 2017 13:40
Last Modified: 06 Oct 2017 13:17
URI: http://sro.sussex.ac.uk/id/eprint/70196

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Project NameSussex Project NumberFunderFunder Ref
Chromosomal Single-strand break Repair: Mechanisms & Degenerative DiseaseG0830MRC-MEDICAL RESEARCH COUNCILMR/J006750/1
Cellular and Pathological Responses to Chromosome DNA Single-Strand BreaksG2053MRC-MEDICAL RESEARCH COUNCILMR/P010121/1