title: Spacing is crucial for coordination of domain functions within the simian virus 40 core origin of replication.
abstract: The simian virus 40 core origin of replication is composed of distinct domains that are bracketed by DNA spacers. We created a matched set of insertion mutations in spacer sites to study the spatial relationships among origin domains. Insertions larger than a single base pair severely inhibit replication regardless of the helical phasing between domains. Replication-defective mutations reduce T-antigen binding and T-antigen-induced KMnO4 modifications of DNA to various extents. Mutations in the early half of the origin reduce T-antigen functions in the entire origin, whereas mutations in the late half reduce functions only in that half. Surprisingly, some mutations that severely inhibit DNA replication reduce T-antigen-induced melting and other structural changes within origin DNA to only a limited extent. In contrast, all replication-defective origin mutations prevent T antigen from extending the primary replication bubble beyond the limits of the core origin of replication. We conclude, therefore, that T-antigen-induced events within the core origin must be spatially coordinated for conversion of T-antigen hexamers bound to the core origin into mobile helicase units.
authors.affiliation: Department of Microbiology, State University of New York, Stony Brook 11794-8621.
authors.forename: R
authors.initials: R
authors.lastname: Parsons
authors.forename: P
authors.initials: P
authors.lastname: Tegtmeyer
mesh_terms: D001483:Base Sequence; D004261:DNA Replication / Q000235:genetics*; D004279:DNA, Viral / Q000096:biosynthesis* / Q000235:genetics; D003850:Deoxyribonuclease I / Q000378:metabolism; D008969:Molecular Sequence Data; D016254:Mutagenesis, Insertional; D011196:Potassium Permanganate / Q000494:pharmacology; D013539:Simian virus 40 / Q000235:genetics* / Q000502:physiology; D014162:Transfection; D014779:Virus Replication / Q000235:genetics
chemical_list: D004279:DNA, Viral; D011196:Potassium Permanganate; D003850:Deoxyribonuclease I