title: Conservation of structure and subunit interactions in yeast homologues of splicing factor 3b (SF3b) subunits.
abstract: Human SAP 49, a subunit of the multimeric splicing factor 3b (SF3b), contains two RNA recognition motifs (RRMs) and binds another SF3b subunit called SAP 145, whose yeast homologue is CUS1. Here we show that the predicted yeast open reading frame YOR319w (HSH49) encodes an essential yeast splicing factor. Using bacterially expressed proteins, we find that yeast HSH49 binds CUS1. Mutations that alter putative RNA-binding residues of either HSH49 RRM are lethal in vivo, but do not prevent binding to CUS1 in vitro, suggesting that the predicted RNA-binding surfaces of HSH49 are not required for interaction with CUS1. In vivo interaction tests show that HSH49 and CUS1 associate primarily through the N-terminal RRM of HSH49. Recombinant HSH49 protein has a general RNA-binding activity that does not require CUS1. The parallels in structure and interaction between two SF3b subunits from yeast implies that the mechanism of SF3b action is highly conserved.
authors.affiliation: Center for the Molecular Biology of RNA, Biology Department, University of California at Santa Cruz, 95064, USA.
authors.forename: H
authors.initials: H
authors.lastname: Igel
authors.forename: S
authors.initials: S
authors.lastname: Wells
authors.forename: R
authors.initials: R
authors.lastname: Perriman
authors.forename: M
authors.initials: M
authors.lastname: Ares
mesh_terms: D000595:Amino Acid Sequence; D001665:Binding Sites; D017124:Conserved Sequence; D005656:Fungal Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D008969:Molecular Sequence Data; D012326:RNA Splicing; D000072260:RNA Splicing Factors; D012331:RNA, Fungal / Q000378:metabolism; D016601:RNA-Binding Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D017413:Ribonucleoprotein, U2 Small Nuclear; D012441:Saccharomyces cerevisiae / Q000235:genetics; D029701:Saccharomyces cerevisiae Proteins; D017386:Sequence Homology, Amino Acid
chemical_list: C097976:CUS1 protein, S cerevisiae; D005656:Fungal Proteins; C110066:HSH49 protein, S cerevisiae; D000072260:RNA Splicing Factors; D012331:RNA, Fungal; D016601:RNA-Binding Proteins; D011993:Recombinant Fusion Proteins; D017413:Ribonucleoprotein, U2 Small Nuclear; C486348:SF3B2 protein, human; C486347:SF3B4 protein, human; D029701:Saccharomyces cerevisiae Proteins