PWWP domains and their modes of sensing DNA and histone methylated lysines.

Chromatin plays an important role in gene transcription control, cell cycle progression, recombination, DNA replication and repair. The fundamental unit of chromatin, the nucleosome, is formed by a DNA duplex wrapped around an octamer of histones. Histones are susceptible to various post-translational modifications, covalent alterations that change the chromatin status. Lysine methylation is one of the major post-translational modifications involved in the regulation of chromatin function. The PWWP domain is a member of the Royal superfamily that functions as a chromatin methylation reader by recognizing both DNA and histone methylated lysines. The PWWP domain three-dimensional structure is based on an N-terminal hydrophobic β-barrel responsible for histone methyl-lysine binding, and a C-terminal α-helical domain. In this review, we set out to discuss the most recent literature on PWWP domains, focusing on their structural features and the mechanisms by which they specifically recognize DNA and histone methylated lysines at the level of the nucleosome.