title: Characterization of the ptr5+ gene involved in nuclear mRNA export in fission yeast.
abstract: To analyze the mechanisms of mRNA export from the nucleus to the cytoplasm, we have isolated eleven mutants, ptr [poly(A)(+) RNA transport] 1 to 11, which accumulate poly(A)(+) RNA in the nucleus at a nonpermissive temperature in Schizosaccharomyces pombe. Of those, the ptr5-1 mutant shows dots- or a ring-like accumulation of poly(A)(+) RNA at the nuclear periphery after shifting to the nonpermissive temperature. We cloned the ptr5(+) gene and found that it encodes a component of the nuclear pore complex (NPC), nucleoporin 85 (Nup85). The ptr5-1 mutant shows no defects in protein transport, suggesting the specific involvement of Ptr5p/Nup85p in nuclear mRNA export in S. pombe. We identified Seh1p, a nucleoporin interacting with Nup85p, an mRNA-binding protein Mlo3p, and Sac3p, a component of the TREX-2 complex involved in coupling of nuclear mRNA export with transcription, as multi-copy suppressors for the ptr5-1 mutation. In addition, we found that the ptr5-1 mutation is synthetically lethal with a mutation of the mRNA export factor Rae1p, and that the double mutant exaggerates defective nuclear mRNA export, suggesting that Ptr5p/Nup85p is involved in nuclear mRNA export through Rae1p. Interestingly, the ptr5-1 mutation also showed synthetic effects with several prp pre-mRNA splicing mutations, suggesting a functional linkage between the NPCs and the splicing apparatus in the yeast nucleus.
authors.affiliation: Department of Biological Sciences, Graduate School of Science and Technology, Kumamoto University, Kurokami, Kumamoto 860-8555, Japan.
authors.forename: Nobuyoshi
authors.initials: N
authors.lastname: Watanabe
authors.forename: Terumasa
authors.initials: T
authors.lastname: Ikeda
authors.forename: Fumitaka
authors.initials: F
authors.lastname: Mizuki
authors.forename: Tokio
authors.initials: T
authors.lastname: Tani
mesh_terms: D021581:Active Transport, Cell Nucleus; D017398:Alternative Splicing; D002467:Cell Nucleus / Q000378:metabolism*; D005800:Genes, Fungal; D034521:Nuclear Matrix-Associated Proteins / Q000235:genetics / Q000378:metabolism; D028861:Nuclear Pore Complex Proteins / Q000235:genetics / Q000378:metabolism*; D029543:Nucleocytoplasmic Transport Proteins / Q000235:genetics / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism*; D016601:RNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D012568:Schizosaccharomyces / Q000235:genetics / Q000378:metabolism*; D029702:Schizosaccharomyces pombe Proteins / Q000235:genetics / Q000378:metabolism*; D013489:Suppression, Genetic
chemical_list: C503583:Mlo3 protein, S pombe; D034521:Nuclear Matrix-Associated Proteins; D028861:Nuclear Pore Complex Proteins; D029543:Nucleocytoplasmic Transport Proteins; C571155:Nup85 protein, S pombe; D012333:RNA, Messenger; D016601:RNA-Binding Proteins; D029702:Schizosaccharomyces pombe Proteins; C571156:Seh1 protein, S pombe; C092953:rae1 protein, S pombe