Versatility in phospho-dependent molecular recognition of the XRCC1 and XRCC4 DNA-damage scaffolds by aprataxin-family FHA domains
journal contributionposted on 2020-07-14, 13:25 authored by Amy L Cherry, Timothy J Nott, Geoffrey Kelly, Stuart L Rulten, Keith W Caldecott, Stephen J Smerdon
Aprataxin, aprataxin and PNKP-like factor (APLF) and polynucleotide kinase phosphatase (PNKP) are key DNA-repair proteins with diverse functions but which all contain a homologous forkhead-associated (FHA) domain. Their primary binding targets are casein kinase 2-phosphorylated forms of the XRCC1 and XRCC4 scaffold molecules which respectively coordinate single-stranded and double-stranded DNA break repair pathways. Here, we present the high-resolution X-ray structure of a complex of phosphorylated XRCC4 with APLF, the most divergent of the three FHA domain family members. This, combined with NMR and biochemical analysis of aprataxin and APLF binding to singly and multiply-phosphorylated forms of XRCC1 and XRCC4, and comparison with PNKP reveals a pattern of distinct but overlapping binding specificities that are differentially modulated by multi-site phosphorylation. Together, our data illuminate important differences between activities of the three phospho-binding domains, in spite of a close evolutionary relationship between them.
DNA break repairDNA-damage signallingFHA domainAmino Acid SequenceBinding SitesCasein Kinase IICrystallography, X-RayDNA DamageDNA RepairDNA Repair EnzymesDNA-(Apurinic or Apyrimidinic Site) LyaseDNA-Binding ProteinsHumansMolecular Sequence DataNuclear Magnetic Resonance, BiomolecularNuclear ProteinsPhosphorylationPhosphotransferases (Alcohol Group Acceptor)Poly-ADP-Ribose Binding ProteinsProtein Structure, TertiaryX-ray Repair Cross Complementing Protein 1Smerdon U117584228Developmental Biology0601 Biochemistry and Cell Biology