title: Persistence of cruciform structure and preferential location of nucleosomes on some regions of pBR322 and ColE 1 DNAs.
abstract: Inverted repeats of pBR322 and ColE 1 DNAs have been analyzed for the presence of cruciform structures upon formation of nucleosomes, using S1, P1 and restriction enzyme analysis. In both cases the fraction of molecules showing nuclease-sensitive sites is unaffected by the DNA relaxation, owing to the formation of nucleosomes. A kinetic mechanism, based on the freezing of cruciform structures on the nucleosome surface or nearby, is proposed. This hypothesis is supported by a preferential location of nucleosomes at the DNA sequences containing the nuclease-sensitive sites, as indicated by restriction enzyme analysis and electron microscopy visualization after psoralen cross-linking.
mesh_terms: D004262:DNA Restriction Enzymes; D004278:DNA, Superhelical / Q000032:analysis*; D004587:Electrophoresis, Agar Gel; D011564:Furocoumarins; D006657:Histones / Q000032:analysis; D008854:Microscopy, Electron; D009690:Nucleic Acid Conformation; D009707:Nucleosomes / Q000032:analysis*; D010446:Peptide Fragments / Q000032:analysis; D010777:Photochemistry; D010957:Plasmids
chemical_list: D004278:DNA, Superhelical; D011564:Furocoumarins; D006657:Histones; D009707:Nucleosomes; D010446:Peptide Fragments; D004262:DNA Restriction Enzymes