Asf1-like structure of the conserved Yaf9 YEATS domain and role in H2A. Z deposition and acetylation

Chromatin can be modified by posttranslational modifications of histones, ATP-dependent remodeling, and incorporation of histone variants. The Saccharomyces cerevisiae protein Yaf9 is a subunit of both the essential histone acetyltransferase complex NuA4 and the ATP-dependent chromatin remodeling complex SWR1-C, which deposits histone variant H2A.Z into euchromatin. Yaf9 contains a YEATS domain, found in proteins associated with multiple chromatin-modifying enzymes and transcription complexes across eukaryotes. Here, we established the conservation of YEATS domain function from yeast to human, and determined the structure of this region from Yaf9 by x-ray crystallography to 2.3 angstrom resolution. The Yaf9 YEATS domain consisted of a beta-sandwich characteristic of the Ig fold and contained three distinct conserved structural features. The structure of the Yaf9 YEATS domain was highly similar to that of the histone chaperone Asf1, a similarity that extended to an ability of Yaf9 to bind histones H3 and H4 in vitro. Using structure-function analysis, we found that the YEATS domain was required for Yaf9 function, histone variant H2A.Z chromatin deposition at specific promoters, and H2A.Z acetylation.