Figure 5.

MNase digestion analysis reveals that prenucleosomes are associated with ∼80 bp of DNA. Mono-prenucleosomes were reconstituted by NAP1-mediated deposition onto the central 80 bp of the 601 DNA (with two 5-nt overhangs) and ligated to two free 80-bp DNA fragments (each containing a single 5-nt overhang) to give mono-prenucleosomes that are flanked by 85-bp DNA extensions, as indicated in the diagram. The samples were digested with MNase, and the 5′ ends of the resulting DNA fragments were mapped by primer extension analysis. The 5′ ends of the primers corresponded to the ends of the central 80 bp of the 601 sequences; thus, the majority of the MNase-digested fragments ranged in size from ∼78 to 85 bp. The control lanes show the ends of the unligated (single white dots) and ligated (double white dots) DNA fragments prior to MNase digestion.