PURIFICATION AND PROPERTIES OF AN ATP-DEPENDENT NUCLEOSOME REMODELINGFACTOR

We report the purification of an ATP-dependent nucleosome remodeling f actor (NURF) from Drosophila embryo extracts. NURF is composed of at l east four polypeptides that act in concert with the GAGA transcription factor to alter chromatin structure at the hsp70 promoter. The energy requirement is attributed to an ATPase activity that is stimulated by nucleosomes but not by free DNA or histones, suggesting that NURF act s directly on a nucleosome to perturb its structure. This finding and the physical properties of NURF contrast sharply with the multisubunit SW12/SNF2 complex, which has also been shown to alter nucleosomes in an ATP-dependent manner. The results suggest that two distinct systems may be involved in remodeling chromatin for transcription.