Asymmetric nucleosome PARylation at DNA breaks mediates directional nucleosome sliding by ALC1.

Bacic L, Gaullier G, Mohapatra J, Mao G, Brackmann K, Panfilov M, Liszczak G, Sabantsev A, Deindl S

Nat Commun 15 (1) 1000 [2024-02-02; online 2024-02-02]

The chromatin remodeler ALC1 is activated by DNA damage-induced poly(ADP-ribose) deposited by PARP1/PARP2 and their co-factor HPF1. ALC1 has emerged as a cancer drug target, but how it is recruited to ADP-ribosylated nucleosomes to affect their positioning near DNA breaks is unknown. Here we find that PARP1/HPF1 preferentially initiates ADP-ribosylation on the histone H2B tail closest to the DNA break. To dissect the consequences of such asymmetry, we generate nucleosomes with a defined ADP-ribosylated H2B tail on one side only. The cryo-electron microscopy structure of ALC1 bound to such an asymmetric nucleosome indicates preferential engagement on one side. Using single-molecule FRET, we demonstrate that this asymmetric recruitment gives rise to directed sliding away from the DNA linker closest to the ADP-ribosylation site. Our data suggest a mechanism by which ALC1 slides nucleosomes away from a DNA break to render it more accessible to repair factors.

Cryo-EM [Service]

PubMed 38307862

DOI 10.1038/s41467-024-45237-8

Crossref 10.1038/s41467-024-45237-8

pmc: PMC10837151
pii: 10.1038/s41467-024-45237-8

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