1. Academic Validation
  2. DNA repair factor APLF acts as a H2A-H2B histone chaperone through binding its DNA interaction surface

DNA repair factor APLF acts as a H2A-H2B histone chaperone through binding its DNA interaction surface

  • Nucleic Acids Res. 2018 Aug 21;46(14):7138-7152. doi: 10.1093/nar/gky507.
Ivan Corbeski 1 Klemen Dolinar 1 2 Hans Wienk 1 Rolf Boelens 1 Hugo van Ingen 1 3
Affiliations

Affiliations

  • 1 NMR Spectroscopy, Bijvoet Center for Biomolecular Research, Utrecht University, Padualaan 8, 3584 CH Utrecht, The Netherlands.
  • 2 Group for Nano- and Biotechnological applications, Department of Fundamentals of Electrical Engineering, Mathematics and Physics, University of Ljubljana, Tržaška cesta 25, 1000 Ljubljana, Slovenia.
  • 3 Macromolecular Biochemistry, Leiden Institute of Chemistry, Leiden University, Einsteinweg 55, 2333 CC, Leiden, The Netherlands.
Abstract

Genome replication, transcription and repair require the assembly/disassembly of the nucleosome. Histone chaperones are regulators of this process by preventing formation of non-nucleosomal histone-DNA complexes. Aprataxin and polynucleotide kinase like factor (APLF) is a non-homologous end-joining (NHEJ) DNA repair factor that possesses histone chaperone activity in its acidic domain (APLFAD). Here, we studied the molecular basis of this activity using biochemical and structural methods. We find that APLFAD is intrinsically disordered and binds histone complexes (H3-H4)2 and H2A-H2B specifically and with high affinity. APLFAD prevents unspecific complex formation between H2A-H2B and DNA in a chaperone assay, establishing for the first time its specific histone chaperone function for H2A-H2B. On the basis of a series of nuclear magnetic resonance studies, supported by mutational analysis, we show that the APLFAD histone binding domain uses two aromatic side chains to anchor to the α1-α2 patches on both H2A and H2B, thereby covering most of their DNA-interaction surface. An additional binding site on both APLFAD and H2A-H2B may be involved in the handoff between APLF and DNA or other chaperones. Together, our data support the view that APLF provides not only a scaffold but also generic histone chaperone activity for the NHEJ-complex.

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