ATP-dependent histone octamer sliding mediated by the chromatin remodelingcomplex NURF

Drosophila NURF is an ATP-dependent chromatin remodeling complex that conta ins ISWI, a member of the SW12/SNF2 family of ATPases. We demonstrate that NURF catalyzes the bidirectional redistribution of mononucleosomes reconsti tuted on hsp70 promoter DNA. In the presence of NURF, nucleosomes adopt one predominant position from an ensemble of possible locations within minutes . Movements occur in cis, with no transfer to competing DNA. Migrating inte rmediates trapped by fro III digestion reveal progressive nucleosome motion in increments of several base pairs. All four core histones are retained q uantitatively during this process, indicating that the general integrity of the histone octamer is maintained. We suggest that NURF remodels nucleosom es by transiently decreasing the activation energy for short-range sliding of the histone octamer.