A03 - A poly-ADP-ribose switch releases the autoinhibition of the oncogenic remodeler Alc1/Chd1L
DNA damage rapidly induces the activity of the ADP-ribosyltransferases PARP1, 2 and 3, which act as dynamic post-translational modifiers of chromatin. We discovered that the nucleosome remodeler (Alc1/Chd1L) robustly enriches at poly-ADP-ribose (PAR) synthesis sites upon laser-mediated induction of DNA damage in vivo. The recruitment is mediated by its PAR-binding macrodomain.
The project will utilize biophysical and structural analyses to determine how the Alc1 macrodomain recognizes PAR, conformationally responds to the binding of its allosteric ligand and in turn activates the enzymatic activity of the remodeler. Further, we will exploit our engineering of a constitutively-active Alc1 fragment to characterize sequence motifs that couple ATPase activity to the productive remodelling of chromatin vivo. We will obtain fundamental mechanistic insight into the allosteric activation of a unique remodeller by a post-translational modification.
The human oncogene ALC1/CHD1L greatly decompacts chromatin structure upon UV-induced DNA damage. The chromatin at the DNA damage site is visualised using a photo-activatable histone H2B protein. The same chromatin region that is photo-activated is also damaged by the UV irradiation.