title: Splicing factor slt11p and its involvement in formation of U2/U6 helix II in activation of the yeast spliceosome.
abstract: Slt11p is a new splicing factor identified on the basis of synthetic lethality with a mutation in the 5' end of U2 snRNA, a region that is involved in intermolecular U2/U6 helix II interaction. Slt11p is required for spliceosome assembly. Our genetic results suggest that Slt11p is involved in the base-pairing interaction of U2/U6 helix II in vivo. We showed that the recombinant protein binds to RNAs with some degree of structural specificity. Slt11p also anneals RNA and binds to the resulting duplexes, which contain two separated helical regions. These RNA structures are reminiscent of U2/U6 helix II, which is formed concomitantly with U4/U6 stem II, and suggest that Slt11p facilitates the cooperative formation of helix II in association with stem II in the spliceosome. We show that Slt11p and Slu7p, a second-step factor, interact with each other both in vivo and in vitro and that the binding of Slu7p to Slt11p impairs the RNA-binding activity of the latter. These results suggest that the function of Slt11p is regulated by Slu7p in the spliceosome.
authors.affiliation: Banting and Best Department of Medical Research and Department of Molecular and Medical Genetics, University of Toronto, Toronto, Ontario, Canada M5G 1L6.
authors.forename: D
authors.initials: D
authors.lastname: Xu
authors.forename: J D
authors.initials: JD
authors.lastname: Friesen
mesh_terms: D000595:Amino Acid Sequence; D001483:Base Sequence; D005656:Fungal Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D009690:Nucleic Acid Conformation; D012326:RNA Splicing; D000072260:RNA Splicing Factors; D012331:RNA, Fungal / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D012342:RNA, Small Nuclear / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D016601:RNA-Binding Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D017411:Ribonucleoproteins, Small Nuclear; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins; D017386:Sequence Homology, Amino Acid; D017381:Spliceosomes / Q000378:metabolism*
chemical_list: C422223:ECM2 protein, S cerevisiae; D005656:Fungal Proteins; D000072260:RNA Splicing Factors; D012331:RNA, Fungal; D012342:RNA, Small Nuclear; D016601:RNA-Binding Proteins; D017411:Ribonucleoproteins, Small Nuclear; C095479:SLU7 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; C405484:U2 small nuclear RNA; C405486:U6 small nuclear RNA