title: Cwf16p Associating with the Nineteen Complex Ensures Ordered Exon Joining in Constitutive Pre-mRNA Splicing in Fission Yeast.
abstract: Exons are ligated in an ordered manner without the skipping of exons in the constitutive splicing of pre-mRNAs with multiple introns. To identify factors ensuring ordered exon joining in constitutive pre-mRNA splicing, we previously screened for exon skipping mutants in Schizosaccharomyces pombe using a reporter plasmid, and characterized three exon skipping mutants named ods1 (ordered splicing 1), ods2, and ods3, the responsible genes of which encode Prp2/U2AF59, U2AF23, and SF1, respectively. They form an SF1-U2AF59-U2AF23 complex involved in recognition of the branch and 3' splice sites in pre-mRNA. In the present study, we identified a fourth ods mutant, ods4, which was isolated in an exon-skipping screen. The ods4+ gene encodes Cwf16p, which interacts with the NineTeen Complex (NTC), a complex thought to be involved in the first catalytic step of the splicing reaction. We isolated two multi-copy suppressors for the ods4-1 mutation, Srp2p, an SR protein essential for pre-mRNA splicing, and Tif213p, a translation initiation factor, in S. pombe. The overexpression of Srp2p suppressed the exon-skipping phenotype of all ods mutants, whereas Tif213p suppressed only ods4-1, which has a mutation in the translational start codon of the cwf16 gene. We also showed that the decrease in the transcriptional elongation rate induced by drug treatment suppressed exon skipping in ods4-1. We propose that Cwf16p/NTC participates in the early recognition of the branch and 3' splice sites and cooperates with the SF1-U2AF59-U2AF23 complex to maintain ordered exon joining.
authors: Department of Biological Sciences, Graduate School of Science and Technology, Kumamoto University, Kumamoto, Japan.
authors: Noriko
authors: N
authors: Sasaki-Haraguchi
authors: Department of Biological Sciences, Graduate School of Science and Technology, Kumamoto University, Kumamoto, Japan.
authors: Takeshi
authors: T
authors: Ikuyama
authors: Department of Biological Sciences, Graduate School of Science and Technology, Kumamoto University, Kumamoto, Japan.
authors: Shogo
authors: S
authors: Yoshii
authors: Department of Biological Sciences, Graduate School of Science and Technology, Kumamoto University, Kumamoto, Japan.
authors: Tomoko
authors: T
authors: Takeuchi-Andoh
authors: Regeneron Pharmaceuticals, Inc., Tarrytown, New York, United States of America.
authors: David
authors: D
authors: Frendewey
authors: Department of Biological Sciences, Graduate School of Science and Technology, Kumamoto University, Kumamoto, Japan.
authors: Tokio
authors: T
authors: Tani
mesh_terms: D017398:Alternative Splicing / Q000235:genetics*; D005091:Exons / Q000235:genetics; D007438:Introns / Q000235:genetics; D046912:Multiprotein Complexes / Q000235:genetics*; D009154:Mutation; D012322:RNA Precursors / Q000235:genetics; D022821:RNA Splice Sites / Q000235:genetics; D012326:RNA Splicing / Q000235:genetics; D000072260:RNA Splicing Factors; D012568:Schizosaccharomyces / Q000235:genetics; D029702:Schizosaccharomyces pombe Proteins / Q000235:genetics*; D017381:Spliceosomes / Q000235:genetics*
chemical_list: D046912:Multiprotein Complexes; D012322:RNA Precursors; D022821:RNA Splice Sites; D000072260:RNA Splicing Factors; D029702:Schizosaccharomyces pombe Proteins; C000607474:bpb1 protein, S pombe