title: Multiple DNA secondary structures in perfect inverted repeat inserts in plasmids. Right-handed B-DNA, cruciforms, and left-handed Z-DNA.
abstract: The capabilities of five recombinant plasmids, containing relatively long (approximately 60-100 base pairs) perfect inverted repeat (IR) inserts, to support supercoil stabilized non-B-DNA structures were studied in vitro. The IRs were also alternating purine-pyrimidine sequences, thus, each could form either left-handed Z-DNA or cruciforms. Single-strand specific endonucleases, restriction endonucleases and methylases, and OsO4 modifications were used to characterize the DNA structures. Two-dimensional gel electrophoretic studies indicated that three of the five IRs formed both cruciforms and Z-DNA. (C-G) containing inserts preferred to form Z-DNA, whereas (T-G) sequences favored cruciforms. In vivo supercoil relaxation experiments demonstrated the existence of cruciforms in Escherichia coli. The physiological significance of these structures is discussed.
authors.affiliation: Department of Biochemistry, School of Medicine, University of Alabama, Birmingham 35294.
authors.forename: J A
authors.initials: JA
authors.lastname: Blaho
authors.forename: J E
authors.initials: JE
authors.lastname: Larson
authors.forename: M J
authors.initials: MJ
authors.lastname: McLean
authors.forename: R D
authors.initials: RD
authors.lastname: Wells
mesh_terms: D001483:Base Sequence; D004262:DNA Restriction Enzymes; D004251:DNA Transposable Elements; D004269:DNA, Bacterial / Q000648:ultrastructure*; D004278:DNA, Superhelical / Q000648:ultrastructure; D004926:Escherichia coli / Q000235:genetics*; D007700:Kinetics; D008958:Models, Molecular; D009690:Nucleic Acid Conformation; D010957:Plasmids
chemical_list: D004251:DNA Transposable Elements; D004269:DNA, Bacterial; D004278:DNA, Superhelical; D004262:DNA Restriction Enzymes