PARP1 directly disassembles nucleosomes to regulate DNA repair.

Researchers found that PARP1 directly and asymmetrically evicts histone dimers near DNA strand breaks, disassembling nucleosomes into oriented hexasomes. In the presence of HPF1, PARP1 forms stable PARylated hexasomes that promote recruitment of DNA- and PAR-dependent factors. In human cells, PARP activity directly increases chromatin accessibility and generates subnucleosomal species.