Crystal structure of yeast Esa1 suggests a unified mechanism for catalysis and substrate binding by histone acetyltransferases.

Esa1 is the catalytic subunit of the NuA4 histone acetylase (HAT) complex that acetylates histone H4, and it is a member of the MYST family of HAT proteins that includes the MOZ oncoprotein and the HIV-1 Tat interacting protein Tip60. Here we report the X-ray crystal structure of the HAT domain of Esa1 bound to coenzyme A and investigate the protein's catalytic mechanism. Our data reveal that Esa1 contains a central core domain harboring a putative catalytic base, and flanking domains that are implicated in histone binding. Comparisons with the Gcn5/PCAF and Hat1 proteins suggest a unified mechanism of catalysis and histone binding by HAT proteins, whereby a structurally conserved core domain mediates catalysis, and sequence variability within a structurally related N- and C-terminal scaffold determines substrate specificity.