Electrophoresis of avian erythroid histones

Analysis of core histones by liquid chromatography-mass spectrometry and peptide mapping

Histone acetylation and methylation are processes that are generally considered to play crucial roles in the chromatin-based regulatory mechanism. Characterization of the histones as well as their modification sites has become increasingly important. In this paper, the use of LC-MS and peptide mapping methods to analyze chicken core histones and identify the modification sites is reported. Microbore C(4) HPLC separated the core histones into H2A, H2B, H3 and H4 using HFBA as the ion-pairing agent. The four subclasses of histones and their putative acetylated or methylated isoforms were identified by LC-MS simultaneously. MALDI-TOF and tandem mass spectrometry provided peptide mapping of the modification sites of the histones through trypsin digestion of the HPLC eluents. This approach is straightforward and prospective for further application in the field of chromatin research.

The vertebrate linker histones H1 zero, H5, and H1M are descendants of invertebrate "orphon" histone H1 genes

We investigated the evolutionary history of the divergent vertebrate linker histones H1 zero, H5, and H1M. We observed that the sequence of the central conserved domain of these vertebrate proteins shares characteristic features with histone H1 proteins of plants and invertebrate animals which otherwise never appear in any vertebrate histone H1 protein. A quantitative analysis of 58 linker histone sequences also reveals that these proteins are more similar to invertebrate and plant histone H1 than to histone H1 of vertebrates. A phylogenetic tree deduced from an alignment of the central domain of all known linker histones places H1 zero, H5, and H1M in close vicinity to invertebrate sperm histone H1 proteins and to invertebrate histone H1 proteins encoded by polyadenylated mRNAs. We therefore conclude that the ancestors of the vertebrate linker histones H1 zero, H5, and H1M diverged from the main group of histone H1 proteins before the vertebrate type of histone H1 was established in evolution. We discuss this observation in the general context of linker histone evolution.