Mechanistic Insights into Autoinhibition of the Oncogenic Chromatin Remodeler ALC1

• DOI: 10.1016/j.molcel.2017.10.017
• Publication Date: 2017-12-07T17:39:50Z
• Authors: Laura C. Lehmann; Graeme Hewitt; Shintaro Aibara; Alexander Leitner; Emil Marklund; Sarah L. Maslen; Varun Maturi; Yang Chen; David van der Spoel; J. Mark Skehel; Aristidis Moustakas; Simon J. Boulton; Sebastian Deindl
• Keywords: 0301 basic medicine; DNA Repair; Cell- och molekylärbiologi; Static Electricity; Poly (ADP-Ribose) Polymerase-1; Molecular Dynamics Simulation; Article; Poly ADP Ribosylation; 03 medical and health sciences; Catalytic Domain; Cell Line, Tumor; Scattering, Small Angle; Humans; Protein Interaction Domains and Motifs; DNA Helicases; Chromatin Assembly and Disassembly; Nucleosomes; DNA-Binding Proteins; Enzyme Activation; Microscopy, Electron; Protein Transport; Mutation; Cell and Molecular Biology; DNA Damage; Protein Binding

Human ALC1 is an oncogene-encoded chromatin-remodeling enzyme required for DNA repair that possesses a poly(ADP-ribose) (PAR)-binding macro domain. Its engagement with PARylated PARP1 activates ALC1 at sites of DNA damage, but the underlying mechanism remains unclear. Here, we establish a dual role for the macro domain in autoinhibition of ALC1 ATPase activity and coupling to nucleosome mobilization. In the absence of DNA damage, an inactive conformation of the ATPase is maintained by juxtaposition of the macro domain against predominantly the C-terminal ATPase lobe through conserved electrostatic interactions. Mutations within this interface displace the macro domain, constitutively activate the ALC1 ATPase independent of PARylated PARP1, and alter the dynamics of ALC1 recruitment at DNA damage sites. Upon DNA damage, binding of PARylated PARP1 by the macro domain induces a conformational change that relieves autoinhibitory interactions with the ATPase motor, which selectively activates ALC1 remodeling upon recruitment to sites of DNA damage.