AF9 Links Histone Acetylation to DOT1L-Mediated H3K79 Methylation

The recognition of modified histones by “reader” proteins constitutes a key mechanism regulating gene expression in the chromatin context. Compared with the great variety of readers for histone methylation, few protein modules that recognize histone acetylation are known. Here we show that the evolutionarily conserved YEATS domains constitute a novel family of acetyllysine readers. The human AF9 YEATS domain binds strongly to histone H3K9 acetylation and, to a lesser extent, H3K27 and H3K18 acetylation. Crystal structural studies revealed that AF9 YEATS adopts an eight-stranded immunoglobin fold and utilizes a serine-lined aromatic “sandwiching” cage for acetyllysine readout, representing a novel recognition mechanism that is distinct from that of known acetyllysine readers. Histone acetylation recognition by AF9 is important for the chromatin recruitment of the H3K79 methyltransferase DOT1L. Together, our studies identify the YEATS domain as a novel acetyllysine-binding module, thereby establishing the first direct link between histone acetylation and DOTL1-mediated H3K79 methylation in transcription control. ChIP-seq analysis of AF9, H3K79me3, H3K9ac in Hela cells and H3K79me3 in Hela AF9 knockdown and Hela Dot1L knockdown cells.