ACTIVATED RSC-NUCLEOSOME COMPLEX AND PERSISTENTLY ALTERED FORM OF THENUCLEOSOME

RSC, an abundant, essential chromatin-remodeling complex, related to S WI/SNF complex, binds nucleosomes and naked DNA with comparable affini ties, as shown by gel shift analysis. The RSC-nucleosome complex is co nverted in the presence of ATP to a slower migrating form. This activa ted complex exhibits greatly increased susceptibility to endo- and exo nucleases but retains a full complement of histones. Activation persis ts in the absence of ATP, and on removal of RSC, the nucleosome is rel eased in an altered form, with a diminished electrophoretic mobility, greater sedimentation rate, and marked instability at elevated ionic s trength. The reaction is reversible in the presence of RSC and ATP, wi th conversion of the altered form back to the nucleosome.