Assessment of Combinatorial Post-Translational Modifications on All Core Histones in Selected Yeast Mutants Using Top Down Mass Spectrometry

摘要

Histones are subject to various modifications which in combination create specific modification patterns along different chromatin regions to define diverse cellular events. Global assessment of histone modifications provides a powerful tool to study the function of different histone modifying enzymes and the interplay among them. Here, we showed a global view of all core histones in yeast provided by tandem mass spectrometry of intact histones. This allowed detailed characterization of >50 distinct histone forms and quantitative assessment of them in more than 15 mutants, including Gcn5 and other well known HATs, HDACs and HMTs. We not only showed the combination of modifications but also the direct linkage between lys-4 tri-methylation and acetylation levels on the same histone H3 tail. By using this strategy, we also identified distinct histone PTMs that correlate with their ability to resist apoptosis in different mutants.