[DOT1: a distinct class of histone lysine methyltransferase].

Lysine methylation is an important covalent modification of histone and has fundamental and divers roles in biological processes including regulation of chromatin structure dynamics and gene expression. Recently, a distinct class of histone lysine methyltransferase DOT1 was found to methylate histone H3 lysine79 (H3K79) residue, which is located on the accessible face of the core nucleosome. The DOT1 proteins do not contain a SET domain, a conserved sequence motif found in all previously characterized histone H3 lysine methyltransferases that act on the histone N-termianl tail. The characteristics of DOT1 proteins and H3K79 methylation suggest that they may have important and characteristic functions. Here, we summarize recent advances in specific structure of DOT1 protein, biological functions of DOT1 proteins and H3K79 methylation and trans-histone regulatory1 between histone H2B ubiquitination and H3K79 methylation.