Gcn5 regulates the dissociation of SWI/SNF from chromatin by acetylation of Swi2/Snf2.

The positive link between the SWI/SNF and the Gcn5 histone acetyltransferase in transcriptional activation has been well described. Here we report an inhibitory role for Gcn5 in SWI/SNF targeting. We demonstrate that Gcn5-containing complexes directly acetylate the Snf2 subunit of the SWI/SNF complex in vitro, as well as in vivo. Moreover, the acetylation of Snf2 facilitates the dissociation of the SWI/SNF complex from acetylated histones, and reduces its association with promoters in vivo. These data reveal a novel mechanism by which Gcn5 modulates chromatin structure not only through the acetylation of histones, but also by directly acetylating Snf2.