Functional delineation of three groups of the ATP-dependent family of chromatin remodeling enzymes

ATP-dependent chromatin remodeling enzymes antagonize the inhibitory effect s of chromatin. We com pare six different remodeling complexes: ySWI/SNF, y RSC, hSWI/SNF, xMi-2, dCHRAC, and dNURF. We find that each complex uses sim ilar amounts of ATP to remodel nucleosomal arrays at nearly identical rates . We also perform assays with arrays reconstituted with hyperacetylated or trypsinized histones and isolated histone (H3/H4)(2) tetramers. The results define three groups of the ATP-dependent family of remodeling enzymes. In addition we investigate the ability of an acidic activator to recruit remod eling complexes to nucleosomal arrays. We propose that ATP-dependent chroma tin remodeling enzymes share a common reaction mechanism and that a key dis tinction between complexes is in their mode of regulation or recruitment.