Ordered recruitment of transcription and chromatin remodeling factors to acell cycle- and developmentally regulated promoter

Gene activation in eukaryotes requires chromatin remodeling complexes like Swi/Snf and histone acetylases like SAGA. How these factors are recruited t o promoters is not yet understood. Using CHIP, we measured recruitment of S wi/Snf, SAGA, the repressor Ash1p, and transcription factors Swi5p and SBF to the HO endonuclease promoter as cells progress through the yeast cell cy cle. Swi5p's entry into nuclei at the end of anaphase recruits Swi/Snf, whi ch then recruits SAGA. These two factors then facilitate SBF's binding. Ash 1p, which only accumulates in daughter cell nuclei, binds to HO soon after Swi5p and aborts recruitment of Swi/Snf, SAGA, and SBF. Swi5p remains at HO for only 5 min. Swi/Snf's and SAGA's subsequent persistence at HO is self sustaining and constitutes an "epigenetic memory" of HO's transient interac tion with Swi5p.