Biological Sciences

Events and seminars

Poly-ADP-ribose releases the autoinhibition of the oncogenic chromatin remodeler Alc1

Andreas Ladurner, Ludwig-Maximilians-Universitat Munchen

22nd November 2016 at 1:00pm [Download iCalendar / .ics file]

Michael Swann Bulding, 7.15

Chromatin remodeling enzymes are essential in order to establish, alter or maintain eukaryotic chromatin structure and function. Their recruitment to the chromatin template is regulated by the presence of globular proteins domains capable of recognizing post-translationally modified histones, such as specific acetyl-lysine or methyl-lysine marks recognized by bromodomains and chromodomains, respectively. Increasing evidence, however, also suggests that post-translational modifications regulate the enzymatic activity of remodelers, and not just their recruitment. We will present unpublished work showing that the enzymatic activity of the human poly-ADP-ribose-dependent nucleosome remodeler Alc1/Chd1L is regulated exquisitely by oligomeric ADP-ribose ligands. Specifically, we find that tri-ADP-ribose binds the C-terminal macrodomain of the remodelers with nanomolar affinity, which in turns leads to a loss of intramolecular interaction with the catalytic Snf2 domain of the remodelers ATPase. ITC assays, MS-coupled H/D-exchange measurements, site-directed mutagenesis as well as real-time, live-cell imaging provide molecular insight into the allosteric activation of this remodeler mediated by oligomeric forms of ADP-ribose. Our data provide a mechanistic basis for Alc1/Chd1L’s function as an exquisite sensor of the DNA-damage-induced and PARP1-mediated synthesis of poly-ADP-ribose, fully consistent with the rapid recruitment of Alc1/Chd1L to DNA damage sites in live cells. Our data reveal an unprecedented mechanism for the ligand-induced, allosteric regulation of a critical remodeling enzyme and oncogene.

Host Philipp Voigt and Atlanta Cook

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