title: In vivo existence of left-handed DNA.
abstract: A genetic-biochemical assay has been developed to investigate the in vivo existence and consequences of unusual DNA structures. Left-handed DNA was shown to exist in living Escherichia coli. The EcoRI methyltransferase gene (temperature-sensitive) was cloned to serve as a probe for perturbed GAATTC sites in vivo. This plasmid was cotransformed with different plasmids containing inserts that had varying capacities to form left-handed helices or cruciforms with a target EcoRI site in the center or at the ends of the inserts. Inhibition of methylation in vivo was found for the stable inserts with the longest left-handed helices. In vitro methylation with the purified M.EcoRI enzyme agreed with the in vivo results.
authors.affiliation: Department of Biochemistry, School of Medicine, University of Alabama, Birmingham 35294.
authors.forename: A
authors.initials: A
authors.lastname: Jaworski
authors.forename: W
authors.initials: W
authors.lastname: Zacharias
authors.forename: W T
authors.initials: WT
authors.lastname: Hsieh
authors.forename: J A
authors.initials: JA
authors.lastname: Blaho
authors.forename: J E
authors.initials: JE
authors.lastname: Larson
authors.forename: R D
authors.initials: RD
authors.lastname: Wells
mesh_terms: D001426:Bacterial Proteins / Q000378:metabolism*; D001483:Base Sequence; D004247:DNA / Q000032:analysis*; D004269:DNA, Bacterial / Q000378:metabolism / Q000648:ultrastructure*; D004274:DNA, Recombinant / Q000378:metabolism; D007700:Kinetics; D008745:Methylation; D009690:Nucleic Acid Conformation; D010957:Plasmids; D015265:Site-Specific DNA-Methyltransferase (Adenine-Specific) / Q000378:metabolism*
chemical_list: D001426:Bacterial Proteins; D004269:DNA, Bacterial; D004274:DNA, Recombinant; D004247:DNA; C020098:DNA modification methylase EcoRI; D015265:Site-Specific DNA-Methyltransferase (Adenine-Specific)