Similar yet critically different: the distribution, dynamics and function of histone variants

Variants of core and linker histones show specific expression patterns and genomic distribution making an essential contribution to the combinatorial complexity of Arabidopsis chromatin structure. Abstract Organization of the genetic information into chromatin plays an important role in the regulation of all DNA template-based reactions. The incorporation of different variant versions of the core histones H3, H2A, and H2B, or the linker histone H1 results in nucleosomes with unique properties. Histone variants can differ by only a few amino acids or larger protein domains and their incorporation may directly affect nucleosome stability and higher order chromatin organization or indirectly influence chromatin function through histone variant-specific binding partners. Histone variants employ dedicated histone deposition machinery for their timely and locus-specific incorporation into chromatin. Plants have evolved specific histone variants with unique expression patterns and features. In this review, we discuss our current knowledge on histone variants in Arabidopsis, their mode of deposition, variant-specific post-translational modifications, and genome-wide distribution, as well as their role in defining different chromatin states.