Abstract A42: Identification of glutamate and aspartate ADP-ribosylation sites onto histones by mass mass spectrometry

Chromatin structure and function is regulated by histone post-translational modifications. Histone proteins are subject to a variety of post-translational modifications that can work combinatorially to alter the transcriptional state or the repair of DNA damage. The landscape of histone modifications includes mono- and poly(ADP-ribosylation), which can directly alter nucleosome structure and DNA accessibility. ADP-ribosylation occuring on glutamate and aspartate residues was the most intensively studied histone ADP-ribosylation modification in the past, primarily because these carboxylester-type ADP-ribose–protein bonds were the most susceptible to hydroxylamine hydrolysis, a particularly fast and efficient method of protein de-ADP-ribosylation. Taking advantage of hydroxylamine-based developments in the identification of ADP-ribosylated residues by liquid-chromatography tandem mass spectrometry (LC-MS/MS), we generated a repertoire of glutamate- and aspartate-specific ADP-ribosylation sites onto histones. In our study, high confidence MS/MS-assigned ADP-ribosylation site identification onto a combination of in vitro and in vivo ADP-ribosylated histones revealed that all five major classes of histones are targets for D/E ADP-ribosylation. We found that the histone tails are not the sole location of the sites of ADP-ribosylation. Significant ADP-ribosylation sites were located in central globular regions of histones adding to the complexity of the histone modification landscape. Citation Format: Jean-Philippe Gagne, Florence Roux-Dalvai, Daniel Defoy, Arnaud Droit, Hendzel J. Michael, Guy G. Poirier. Identification of glutamate and aspartate ADP-ribosylation sites onto histones by mass mass spectrometry [abstract]. In: Proceedings of the AACR Special Conference on DNA Repair: Tumor Development and Therapeutic Response; 2016 Nov 2-5; Montreal, QC, Canada. Philadelphia (PA): AACR; Mol Cancer Res 2017;15(4_Suppl):Abstract nr A42.