Nucleosome signalling; An evolving concept

The enzymes responsible for placing and removing histone modifications, and the modification-binding proteins themselves, are ubiquitous, numerous and conserved amongst eukaryotes. Like the nucleosome, they date back to the earliest eukaryotes and may have played integral and essential roles in eukaryotic evolution. The present properties and epigenetic functions of the nucleosome reflect its evolutionary past and the selective pressures to which it has responded and can be better understood in this context. This article is part of a Special Issue entitled: Molecular mechanisms of histone modification function.