title: The U5 snRNA internal loop 1 is a platform for Brr2, Snu114 and Prp8 protein binding during U5 snRNP assembly.
abstract: The U5 small nuclear ribonucleoprotein particle (snRNP) forms the heart of the spliceosome which is required for intron removal from pre-mRNA. The proteins Prp8, Snu114 and Brr2 all assemble with the U5 small nuclear RNA (snRNA) to produce the U5 snRNP. Successful assembly of the U5 snRNP, then incorporation of this snRNP into the U4/U6.U5 tri-snRNP and the spliceosome, is essential for producing an active spliceosome. We have investigated the requirements for Prp8, Snu114 and Brr2 association with the U5 snRNA to form the U5 snRNP in yeast. Mutations were constructed in the highly conserved loop 1 and internal loop 1 (IL1) of the U5 snRNA and their function assessed in vivo. The influence of these U5 mutations on association of Prp8, Snu114 and Brr2 with the U5 snRNA were then determined. U5 snRNA loop 1 and both sides of IL1 in U5 were important for association of Prp8, Snu114 and Brr2 with the U5 snRNA. Mutations in the 3' side of U5 IL1 resulted in the greatest reduction of Prp8, Snu114 and Brr2 association with the U5 snRNA. Genetic screening of brr2 and U5 snRNA mutants revealed synthetic lethal interactions between alleles in Brr2 and the 3' side of U5 snRNA IL1 which reflects reduced association between Brr2 and U5 IL1. We propose that the U5 snRNA IL1 is a platform for protein binding and is required for Prp8, Brr2 and Snu114 association with the U5 snRNA to form the U5 snRNP.
authors.affiliation: Faculty of Life Sciences, The University of Manchester, Michael Smith Building, Oxford Road, Manchester, M13 9PT, United Kingdom.
authors.forename: Verity
authors.initials: V
authors.lastname: Nancollis
authors.forename: Jayalath P D
authors.initials: JP
authors.lastname: Ruckshanthi
authors.forename: Lily Novak
authors.initials: LN
authors.lastname: Frazer
authors.forename: Raymond T
authors.initials: RT
authors.lastname: O'Keefe
mesh_terms: D009154:Mutation; D009690:Nucleic Acid Conformation; D011485:Protein Binding / Q000235:genetics; D020365:RNA Helicases / Q000235:genetics* / Q000378:metabolism; D012342:RNA, Small Nuclear / Q000235:genetics* / Q000378:metabolism; D017414:Ribonucleoprotein, U4-U6 Small Nuclear / Q000235:genetics* / Q000378:metabolism; D017415:Ribonucleoprotein, U5 Small Nuclear / Q000235:genetics* / Q000378:metabolism; D017411:Ribonucleoproteins, Small Nuclear; D012441:Saccharomyces cerevisiae / Q000235:genetics; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics* / Q000378:metabolism; D017381:Spliceosomes / Q000235:genetics / Q000378:metabolism / Q000648:ultrastructure
chemical_list: C077018:PRP8 protein, S cerevisiae; D012342:RNA, Small Nuclear; D017414:Ribonucleoprotein, U4-U6 Small Nuclear; D017415:Ribonucleoprotein, U5 Small Nuclear; D017411:Ribonucleoproteins, Small Nuclear; C472240:SNU114 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; C405485:U5 small nuclear RNA; C104158:BRR2 protein, S cerevisiae; D020365:RNA Helicases
keywords: Brr2; PRE-mRNA SPLICING; Prp8; SACCHAROMYCES CEREVISIAE; SPLICEOSOME; Snu114; U5 snRNP