The Isw2 chromatin remodeling complex represses early meiotic genes upon recruitment by Ume6p

The ISWI class of chromatin remodeling factors exhibits potent chromatin re modeling activities in vitro. However, the in vivo functions of this class of factors are unknown at a molecular level. We have found that S. cerevisi ae Isw2 complex represses transcription of early meiotic genes during mitot ic growth in a parallel pathway to Rpd3-Sin3 histone deacetylase complex. T his repressor function of lsw2 complex is largely dependent upon Ume6p, whi ch recruits the complex to target genes. Nuclease digestion analyses reveal ed that Isw2 complex establishes nuclease-inaccessible chromatin structure near the Ume6p binding site in vivo. Based on these findings, we propose a model for the mechanism of transcriptional repression by two distinct chrom atin remodeling complexes.