title: Characterization of histone H2A and H2B variants and their post-translational modifications by mass spectrometry.
abstract: The nucleosome, the fundamental structural unit of chromatin, contains an octamer of core histones H3, H4, H2A, and H2B. Incorporation of histone variants alters the functional properties of chromatin. To understand the global dynamics of chromatin structure and function, analysis of histone variants incorporated into the nucleosome and their covalent modifications is required. Here we report the first global mass spectrometric analysis of histone H2A and H2B variants derived from Jurkat cells. A combination of mass spectrometric techniques, HPLC separations, and enzymatic digestions using endoproteinase Glu-C, endoproteinase Arg-C, and trypsin were used to identify histone H2A and H2B subtypes and their modifications. We identified nine histone H2A and 11 histone H2B subtypes, among them proteins that only had been postulated at the gene level. The two main H2A variants, H2AO and H2AC, as well as H2AL were either acetylated at Lys-5 or phosphorylated at Ser-1. For the replacement histone H2AZ, acetylation at Lys-4 and Lys-7 was found. The main histone H2B variant, H2BA, was acetylated at Lys-12, -15, and -20. The analysis of core histone subtypes with their modifications provides a first step toward an understanding of the functional significance of the diversity of histone structures.
authors.affiliation: Genome and Proteome Sciences, Novartis Institutes for Biomedical Research, CH-4056 Basel, Switzerland.
authors.forename: Débora
authors.initials: D
authors.lastname: Bonenfant
authors.forename: Michèle
authors.initials: M
authors.lastname: Coulot
authors.forename: Harry
authors.initials: H
authors.lastname: Towbin
authors.forename: Patrick
authors.initials: P
authors.lastname: Schindler
authors.forename: Jan
authors.initials: J
authors.lastname: van Oostrum
mesh_terms: D000595:Amino Acid Sequence; D002851:Chromatography, High Pressure Liquid; D006657:Histones / Q000032:analysis / Q000737:chemistry* / Q000378:metabolism*; D006801:Humans; D019169:Jurkat Cells; D013058:Mass Spectrometry; D008969:Molecular Sequence Data; D008970:Molecular Weight; D010455:Peptides / Q000032:analysis / Q000737:chemistry; D011499:Protein Processing, Post-Translational; D020539:Sequence Analysis, Protein
chemical_list: D006657:Histones; D010455:Peptides