Effect of double-strand break DNA sequence on the PARP-1 NHEJ pathway.
Efficient repair of DNA double-strand breaks (DSBs) is critical for the maintenance of genomic integrity. In mammalian cells, DSBs are preferentially repaired by non-homologous end-joining (NHEJ). We have previously described a new DSBs microhomology end-joining pathway depending on PARP-1 and the XRCC1/DNA ligase III complex. In this study we analysed, with recombinant proteins and protein extracts, the effect of DSB end sequences: (i) on the DSB synapsis activity; (ii) on the end-joining activity. We report that PARP-1 DSB synapsis activity is independent of the DSB sequence and could be detected with non-complementary DSBs. We demonstrate also that the efficiency of DSBs repair by PARP-1 NHEJ is strongly dependent on the presence of G:C base pairs at microhomology termini. These results highlight a new role of the PARP-1 protein on the synapsis of DSBs and could explain why the PARP-1 NHEJ pathway is strongly dependent on the DSBs microhomology sequence.
Institut de Pharmacologie et de Biologie Structurale, CNRS UMR5089, 205 route de Narbonne, F-31077 Toulouse, Cedex, France.
Marc
M
Audebert
Bernard
B
Salles
Patrick
P
Calsou
D001482:Base Composition; D001483:Base Sequence; D004247:DNA / Q000737:chemistry* / Q000378:metabolism*; D004260:DNA Repair; D006367:HeLa Cells; D006801:Humans; D000071137:Poly (ADP-Ribose) Polymerase-1; D011065:Poly(ADP-ribose) Polymerases / Q000737:chemistry / Q000378:metabolism*; D011995:Recombination, Genetic
D004247:DNA; C499320:PARP1 protein, human; D000071137:Poly (ADP-Ribose) Polymerase-1; D011065:Poly(ADP-ribose) Polymerases