Elucidating the temporal dynamics of chromatin-associated protein release upon DNA digestion by quantitative proteomic approach

Chromatin is a highly dynamic well organized nucleoprotein complex of DNA and proteins that controls DNA-dependent processes such as transcription, replication, repair and many others. Chromatin structure is regulated by various chromatin associated proteins, post-translational modifications of histones and DNA methylation, but a complete picture of structural changes in chromatin architecture is unclear due to the lack of comprehensive data of chromatin-associated proteins and their bindings to different chromatin regions. This study temporally released chromatin-associated proteins by DNase I and MNase treatment and profiled them by exponentially modified protein abundance index (emPAI) based label-free quantitative proteomics. We identified 694 high confidence proteins, with 160 known chromatin-associated proteins. Identified proteins were functionally classified into histones, non-histones involved in architectural maintenance, proteins involved in DNA replication and repair, transcription machinery, transcription regulation, other chromatin proteins, cell cycle proteins and several novel proteins. Numerous proteins presumed to be chromatin associated were identified and their chromatin interactions were explored. The comprehensive differential chromatin bound proteome might expand our knowledge of the proteins that were associated with different chromatin regions, which could be very useful in elucidating chromatin biology.