RESUMO
Poly(ADP-ribosyl)ation plays a major role in DNA repair, where it regulates chromatin relaxation as one of the critical events in the repair process. However, the molecular mechanism by which poly(ADP-ribose) modulates chromatin remains poorly understood. Here we identify the poly(ADP-ribose)-regulated protein APLF as a DNA-damage-specific histone chaperone. APLF preferentially binds to the histone H3/H4 tetramer via its C-terminal acidic motif, which is homologous to the motif conserved in the histone chaperones of the NAP1L family (NAP1L motif). We further demonstrate that APLF exhibits histone chaperone activities in a manner that is dependent on its acidic domain and that the NAP1L motif is critical for the repair capacity of APLF in vivo. Finally, we identify structural analogs of APLF in lower eukaryotes with the ability to bind histones and localize to the sites of DNA-damage-induced poly(ADP-ribosyl)ation. Collectively, these findings define the involvement of histone chaperones in poly(ADP-ribose)-regulated DNA repair reactions.
Assuntos
Reparo do DNA , Chaperonas de Histonas/fisiologia , Fosfoproteínas/fisiologia , Motivos de Aminoácidos , Animais , Caenorhabditis elegans/genética , Linhagem Celular , Dano ao DNA , DNA Liase (Sítios Apurínicos ou Apirimidínicos) , Eucariotos/genética , Células HeLa , Chaperonas de Histonas/química , Chaperonas de Histonas/genética , Histonas/metabolismo , Humanos , Dados de Sequência Molecular , Fosfoproteínas/química , Fosfoproteínas/genética , Proteínas de Ligação a Poli-ADP-Ribose , Mapeamento de Interação de Proteínas , Proteínas/química , Proteínas/genética , Proteínas/fisiologia , Homologia de Sequência , tRNA MetiltransferasesRESUMO
Addition of poly(ADP-ribose) (PAR) is an important post-translational modification in higher eukaryotes. Several DNA repair and checkpoint proteins possess specific PAR-binding zinc-finger (PBZ) modules critical for function. Here, we present solution structures of the two PBZ modules of aprataxin and PNK-like factor (APLF), revealing a novel type of zinc finger. By combining in vivo PAR-binding data with NMR interaction data using PAR fragments, we propose a structural basis for PBZ-PAR recognition.