Cataloging Posttranslational Modifications in Plant Histones

Eukaryotic DNA exist in the nuclei in the form of a complex with proteins called chromatin. Access to the information encoded in the DNA requires the opening of the chromatin. Modulation of the chromatin structure is therefore an important layer of regulation for DNA-templated processes. The basic unit of the chromatin is the nucleosome, which contains DNA wrapped around an octamer of histones, H2A, H2B, H3, and H4. Because histones are a structural part of the nucleosome, its modification can lead to changes in chromatin structure. Amino acid residues in histones could be modified with at least 20 different types of functional groups leading to a vast number of modified residues. Here, an overview of the histone modifications found in plants is provided. We focus mainly in proteomic-based studies either aimed to identify PTMs on purified histones or proteome-wide analysis of particular modifications. The strategies used for cataloging modifications in plants are also described. Profiling of histone modifications is important to begin to understand their functions as mediators of gene regulation in plant biological systems.