A ribozyme selected from variants of U6 snRNA promotes 2',5'-branch formation.
In vitro selection was used to sample SnRNA-related sequences for ribozyme activities, and several 2',5'-branch-forming ribozymes were isolated. One such ribozyme is highly dependent upon an 11-nt motif that contains a conserved U6 snRNA sequence (ACAGAGA-box) known to be important for pre-mRNA splicing. The ribozyme reaction is similar to the first step of splicing in that an internal 2'-hydroxyl of an unpaired adenosine attacks at the 5'-phosphate of a guanosine. It differs in that the leaving group is diphosphate rather than a 5' exon. The finding that lariat formation can be accomplished by a small RNA with sequences related to U6 snRNA indicates that the RNA available in the spliceosome may be involved in RNA-catalyzed branch formation.
Tuschl
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Department of Biology, Massachusetts Institute of Technology, Cambridge 02139, USA.
Sharp
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PA
Bartel
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D000818:Animals; D001483:Base Sequence; D017124:Conserved Sequence; D005091:Exons; D015723:Gene Library; D014644:Genetic Variation; D007438:Introns; D007700:Kinetics; D008969:Molecular Sequence Data; D009690:Nucleic Acid Conformation; D009838:Oligodeoxyribonucleotides; D010802:Phylogeny; D012322:RNA Precursors / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D012326:RNA Splicing; D016337:RNA, Catalytic / Q000378:metabolism*; D012342:RNA, Small Nuclear / Q000235:genetics*; D012441:Saccharomyces cerevisiae / Q000235:genetics; D016415:Sequence Alignment; D012689:Sequence Homology, Nucleic Acid; D013379:Substrate Specificity; D014351:Trypanosomatina / Q000235:genetics
D009838:Oligodeoxyribonucleotides; D012322:RNA Precursors; D016337:RNA, Catalytic; D012342:RNA, Small Nuclear; C405486:U6 small nuclear RNA