title: A self-splicing group I intron in the nuclear pre-rRNA of the green alga, Ankistrodesmus stipitatus.
abstract: The nuclear small subunit ribosomal RNA gene of the unicellular green alga Ankistrodesmus stipitatus contains a group I intron, the first of its kind to be found in the nucleus of a member of the plant kingdom. The intron RNA closely resembles the group I intron found in the large subunit rRNA precursor of Tetrahymena thermophila, differing by only eight nucleotides of 48 in the catalytic core and having the same peripheral secondary structure elements. The Ankistrodesmus RNA self-splices in vitro, yielding the typical group I intron splicing intermediates and products. Unlike the Tetrahymena intron, however, splicing is accelerated by high concentrations of monovalent cations and is rate-limited by the exon ligation step. This system provides an opportunity to understand how limited changes in intron sequence and structure alter the properties of an RNA catalytic center.
authors.affiliation: Department of Molecular, Cellular and Developmental Biology, Howard Hughes Medical Institute, University of Colorado, Boulder 80309.
authors.forename: J A
authors.initials: JA
authors.lastname: Dávila-Aponte
authors.forename: V A
authors.initials: VA
authors.lastname: Huss
authors.forename: M L
authors.initials: ML
authors.lastname: Sogin
authors.forename: T R
authors.initials: TR
authors.lastname: Cech
mesh_terms: D000818:Animals; D001483:Base Sequence; D002412:Cations / Q000378:metabolism; D000460:Chlorophyta / Q000235:genetics*; D005091:Exons / Q000235:genetics; D007438:Introns / Q000235:genetics*; D007700:Kinetics; D008969:Molecular Sequence Data; D009690:Nucleic Acid Conformation; D012322:RNA Precursors / Q000235:genetics / Q000378:metabolism*; D016337:RNA, Catalytic / Q000235:genetics / Q000378:metabolism*; D013696:Temperature; D013768:Tetrahymena / Q000235:genetics
chemical_list: D002412:Cations; D012322:RNA Precursors; D016337:RNA, Catalytic