We have previously described in mammalian Caspase-3/7 Inhibitor a new DSBs microhomology end-joining pathway, independent of DNA–PK, and relying on the poly(ADP-ribose) polymerase-1 (PARP-1) protein, the XRCC1/DNA ligase III complex [32] and the polynucleotide kinase PNK [33]. This repair pathway is dependent on the microhomology length at the break site [32]. The implication of PARP-1 in an alternative pathway of NHEJ has since been confirmed in vivo and in vitro [34].
In this study, we have tested whether the PARP-1 DSBs microhomology end-joining pathway corresponds to the DNA–PK independent NHEJ and analysed the effect of DSBs termini variants on the PARP-1 end-joining pathway. Using an in vitro approach, we report that the DSBs synapsis efficiency of the PARP-1 protein is independent of the DSBs extremity and can be detected with non-complementary overhang DSB. With recombinant proteins as well as with protein extracts, the PARP-1 NHEJ pathway is strongly dependent on the DSB sequence overhang. PARP-1 NHEJ with a microhomology overhang involving four A:T bases is repaired as efficiently as blunt-end DSB, but this reaction is tenfold lower than with an overhang involving four G:C bases.
View User's Journal
The surface water N O
 |
