  RSC is an essential chromatin remodeling factor that is required for the
control of several processes including transcription, repair and replication.
The ability of RSC to relocate centrally positioned mononucleosomes at the end
of nucleosomal DNA is firmly established, but the data on RSC action on
oligo-nucleosomal templates remains still scarce. By using Atomic Force
Microscopy (AFM) imaging, we have quantitatively studied the RSC- induced
mobilization of positioned di- and trinucleosomes as well as the directionality
of mobilization on mononucleosomal template labeled at one end with
streptavidin. AFM imaging showed only a limited set of distinct configurational
states for the remodeling products. No stepwise or preferred directionality of
the nucleosome motion was observed. Analysis of the corresponding reaction
pathways allows deciphering the mechanistic features of RSC-induced nucleosome
relocation. The final outcome of RSC remodeling of oligosome templates is the
packing of the nucleosomes at the edge of the template, providing large
stretches of DNA depleted of nucleosomes. This feature of RSC may be used by
the cell to overcome the barrier imposed by the presence of nucleosomes.
