title: Bent helix formation between RNA hairpins with complementary loops.
abstract: The initial interaction between the ColE1 plasmid specific transcripts RNA I and RNA II, which function as antisense regulators of plasmid replication, comprises a transient complex between complementary loops found within the RNA secondary structures. Multidimensional heteronuclear magnetic resonance spectroscopy was used to characterize complexes formed between model RNA hairpins having seven nucleotide complementary loops. Seven base pairs are formed in the loop-loop helix, with continuous helical stacking of the loop residues on the 3' side of their helical stems. A sharp bend in the loop-loop helix, documented by gel electrophoresis, narrows the major groove and allows bridging of the phosphodiester backbones across the major groove in order to close the hairpin loops at their 5'-ends. The bend is further enhanced by the binding of Rom, a ColE1 encoded protein that regulates replication.
authors.affiliation: Department of Chemistry, Yale University, New Haven, CT 06511, USA.
authors.forename: J P
authors.initials: JP
authors.lastname: Marino
authors.forename: R S
authors.initials: RS
authors.lastname: Gregorian
authors.forename: G
authors.initials: G
authors.lastname: Csankovszki
authors.forename: D M
authors.initials: DM
authors.lastname: Crothers
mesh_terms: D001426:Bacterial Proteins / Q000737:chemistry / Q000378:metabolism; D003086:Bacteriocin Plasmids / Q000235:genetics*; D001482:Base Composition; D001483:Base Sequence; D003196:Computer Graphics; D004591:Electrophoresis, Polyacrylamide Gel; D018257:Helix-Loop-Helix Motifs; D009682:Magnetic Resonance Spectroscopy; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009690:Nucleic Acid Conformation; D017433:Protein Structure, Secondary; D012313:RNA / Q000737:chemistry* / Q000378:metabolism; D012329:RNA, Bacterial / Q000737:chemistry* / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; C042027:RNA I; C034477:RNA primers; D012329:RNA, Bacterial; C042833:ROM protein, Bacteria; D012313:RNA