title: Yeast ntr1/spp382 mediates prp43 function in postspliceosomes.
abstract: The Ntr1 and Ntr2 proteins of Saccharomyces cerevisiae have been reported to interact with proteins involved in pre-mRNA splicing, but their roles in the splicing process are unknown. We show here that they associate with a postsplicing complex containing the excised intron and the spliceosomal U2, U5, and U6 snRNAs, supporting a link with a late stage in the pre-mRNA splicing process. Extract from cells that had been metabolically depleted of Ntr1 has low splicing activity and accumulates the excised intron. Also, the level of U4/U6 di-snRNP is increased but those of the free U5 and U6 snRNPs are decreased in Ntr1-depleted extract, and increased levels of U2 and decreased levels of U4 are found associated with the U5 snRNP protein Prp8. These results suggest a requirement for Ntr1 for turnover of the excised intron complex and recycling of snRNPs. Ntr1 interacts directly or indirectly with the intron release factor Prp43 and is required for its association with the excised intron. We propose that Ntr1 promotes release of excised introns from splicing complexes by acting as a spliceosome receptor or RNA-targeting factor for Prp43, possibly assisted by the Ntr2 protein.
authors.affiliation: Wellcome Trust Centre for Cell Biology, University of Edinburgh, King's Buildings, Mayfield Road, Edinburgh EH9 3JR, United Kingdom.
authors.forename: Kum-Loong
authors.initials: KL
authors.lastname: Boon
authors.forename: Tatsiana
authors.initials: T
authors.lastname: Auchynnikava
authors.forename: Gretchen
authors.initials: G
authors.lastname: Edwalds-Gilbert
authors.forename: J David
authors.initials: JD
authors.lastname: Barrass
authors.forename: Alastair P
authors.initials: AP
authors.lastname: Droop
authors.forename: Christophe
authors.initials: C
authors.lastname: Dez
authors.forename: Jean D
authors.initials: JD
authors.lastname: Beggs
mesh_terms: D053487:DEAD-box RNA Helicases; D007438:Introns / Q000235:genetics; D011485:Protein Binding; D020365:RNA Helicases / Q000378:metabolism*; D012326:RNA Splicing / Q000235:genetics; D017411:Ribonucleoproteins, Small Nuclear / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000378:metabolism*; D017381:Spliceosomes / Q000378:metabolism*
chemical_list: C507653:Ntr2 protein, S cerevisiae; D017411:Ribonucleoproteins, Small Nuclear; D029701:Saccharomyces cerevisiae Proteins; C507652:Spp382 protein, S cerevisiae; C109034:PRP43 protein, S cerevisiae; D053487:DEAD-box RNA Helicases; D020365:RNA Helicases