title: One binding site determines sequence specificity of Tetrahymena pre-rRNA self-splicing, trans-splicing, and RNA enzyme activity.
abstract: The specificity of reactions catalyzed by the Tetrahymena pre-rRNA intervening sequence (IVS) was studied using site-specific mutagenesis. Two sequences required for 5' splice-site selection during self-splicing were defined. Single-base changes in either a 5' exon sequence or a 5' exon-binding site within the IVS disrupt their ability to pair and result in inefficient or inaccurate splicing. Combinations that restore complementarity suppress the effect of the single-base changes. Sequence alterations in the 5' exon-binding site also change the specificity of two other reactions: intermolecular exon ligation (trans-splicing) and the enzymatic nucleotidyltransferase activity of the IVS RNA. Thus the substrate specificity of an RNA enzyme can be changed in a manner predictable by the rules of Watson-Crick base-pairing.
mesh_terms: D001483:Base Sequence; D001665:Binding Sites; D005091:Exons; D006160:Guanosine Triphosphate / Q000378:metabolism; D007438:Introns; D009154:Mutation; D009690:Nucleic Acid Conformation; D009713:Nucleotidyltransferases / Q000378:metabolism; D012326:RNA Splicing; D012335:RNA, Ribosomal / Q000235:genetics*; D013379:Substrate Specificity; D013698:Templates, Genetic; D013768:Tetrahymena / Q000502:physiology
chemical_list: D012335:RNA, Ribosomal; D006160:Guanosine Triphosphate; D009713:Nucleotidyltransferases