title: Coaxially stacked RNA helices in the catalytic center of the Tetrahymena ribozyme.
abstract: Coaxial stacking of helical elements is a determinant of three-dimensional structure in RNA. In the catalytic center of the Tetrahymena group I intron, helices P4 and P6 are part of a tertiary structural domain that folds independently of the remainder of the intron. When P4 and P6 were fused with a phosphodiester linkage, the resulting RNA retained the detailed tertiary interactions characteristic of the native P4-P6 domain and even required lower magnesium ion concentrations for folding. These results indicate that P4 and P6 are coaxial in the P4-P6 domain and, therefore, in the native ribozyme. Helix fusion could provide a general method for identifying pairs of coaxially stacked helices in biological RNA molecules.
authors.affiliation: Howard Hughes Medical Institute, Department of Chemistry and Biochemistry, University of Colorado, Boulder 80309.
authors.forename: F L
authors.initials: FL
authors.lastname: Murphy
authors.forename: Y H
authors.initials: YH
authors.lastname: Wang
authors.forename: J D
authors.initials: JD
authors.lastname: Griffith
authors.forename: T R
authors.initials: TR
authors.lastname: Cech
mesh_terms: D000818:Animals; D001483:Base Sequence; D004492:Edetic Acid; D004591:Electrophoresis, Polyacrylamide Gel; D005296:Ferrous Compounds; D007438:Introns; D008274:Magnesium / Q000494:pharmacology; D008969:Molecular Sequence Data; D009690:Nucleic Acid Conformation; D016337:RNA, Catalytic / Q000737:chemistry* / Q000648:ultrastructure; D016053:RNA, Protozoan / Q000737:chemistry* / Q000648:ultrastructure; D013768:Tetrahymena / Q000235:genetics*
chemical_list: D005296:Ferrous Compounds; D016337:RNA, Catalytic; D016053:RNA, Protozoan; C055526:Fe(II)-EDTA; D004492:Edetic Acid; D008274:Magnesium