RSC unravels the nucleosome

RSC and SWI/SNF chromatin-remodeling complexes were previously reported to generate a stably altered nucleosome. We now describe the formation of hybr ids between nucleosomes of different sizes, showing that the stably altered structure is a noncovalent dimer. A basis for dimer formation is suggested by an effect of RSC on the supercoiling of closed, circular arrays of nucl eosomes. The effect may be explained by the interaction of RSC with DNA at the ends of the nucleosome, which could lead to the release 60-80 bp or mor e from the ends. DNA released in this way may be trapped in the stable dime r or lead to alternative fates such as histone octamer transfer to another DNA or sliding along the same DNA molecule.