title: Isolation of Z-DNA binding proteins from SV40 minichromosomes: evidence for binding to the viral control region.
abstract: Proteins dissociated from SV40 minichromosomes by increasing NaCl concentration were tested for their binding to Z-DNA [Br-poly(dG-dC)] and B-DNA [poly (dG-dC)]. Z-DNA binding proteins are largely released in 0.2 M NaCl whereas most B-DNA binding proteins are not released until 0.6 M NaCl. Incubation of SV40 minichromosomes with Z-DNA-Sephadex in low salt solution results in proteins with Z-DNA binding activity (PZ proteins). These proteins bind to negatively supercoiled DNAs containing left-handed Z-DNA but not to relaxed DNAs. They compete with anti-Z-DNA antibodies in binding to negatively supercoiled DNAs. The binding is tighter to negatively supercoiled SV40 DNA than to other plasmids, suggesting sequence-specific Z-DNA binding. PZ proteins binding to negatively supercoiled SV40 DNA interfere with cleavage at the Sph I sites, within the 72 bp repeat sequences of the viral control region, but not with cleavage at the Bgl I site, at the origin of replication. Removal of PZ proteins also exposes the Sph I sites in the SV40 minichromosomes while addition of PZ proteins makes the sites inaccessible.
authors.forename: F
authors.initials: F
authors.lastname: Azorin
authors.forename: A
authors.initials: A
authors.lastname: Rich
mesh_terms: D001483:Base Sequence; D001665:Binding Sites; D004261:DNA Replication; D004262:DNA Restriction Enzymes; D004278:DNA, Superhelical / Q000378:metabolism*; D004279:DNA, Viral / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000302:isolation & purification / Q000378:metabolism*; D015252:Deoxyribonucleases, Type II Site-Specific; D005814:Genes, Viral; D008970:Molecular Weight; D009690:Nucleic Acid Conformation; D013539:Simian virus 40 / Q000032:analysis / Q000235:genetics* / Q000378:metabolism; D014764:Viral Proteins / Q000302:isolation & purification / Q000378:metabolism*; D014779:Virus Replication
chemical_list: D004278:DNA, Superhelical; D004279:DNA, Viral; D004268:DNA-Binding Proteins; D014764:Viral Proteins; D004262:DNA Restriction Enzymes; C046184:endodeoxyribonuclease PaeI; D015252:Deoxyribonucleases, Type II Site-Specific; C018492:GCCNNNNNGGC-specific type II deoxyribonucleases