title: Crystal structure of the beta-finger domain of Prp8 reveals analogy to ribosomal proteins.
abstract: Prp8 stands out among hundreds of splicing factors as a key regulator of spliceosome activation and a potential cofactor of the splicing reaction. We present here the crystal structure of a 274-residue domain (residues 1,822-2,095) near the C terminus of Saccharomyces cerevisiae Prp8. The most striking feature of this domain is a beta-hairpin finger protruding out of the protein (hence, this domain will be referred to as the beta-finger domain), resembling many globular ribosomal proteins with protruding extensions. Mutations throughout the beta-finger change the conformational equilibrium between the first and the second catalytic step. Mutations at the base of the beta-finger affect U4/U6 unwinding-mediated spliceosome activation. Prp8 may insert its beta-finger into the first-step complex (U2/U5/U6/pre-mRNA) or U4/U6.U5 tri-snRNP and stabilize these complexes. Mutations on the beta-finger likely alter these interactions, leading to the observed mutant phenotypes. Our results suggest a possible mechanism of how Prp8 regulates spliceosome activation. These results also demonstrate an analogy between a spliceosomal protein and ribosomal proteins that insert extensions into folded rRNAs and stabilize the ribosome.
authors.affiliation: Department of Biochemistry and Molecular Genetics, Anschutz Medical Campus, University of Colorado Denver, Aurora, CO 80045, USA.
authors.forename: Kui
authors.initials: K
authors.lastname: Yang
authors.forename: Lingdi
authors.initials: L
authors.lastname: Zhang
authors.forename: Tao
authors.initials: T
authors.lastname: Xu
authors.forename: Annie
authors.initials: A
authors.lastname: Heroux
authors.forename: Rui
authors.initials: R
authors.lastname: Zhao
mesh_terms: D000595:Amino Acid Sequence; D002384:Catalysis; D018360:Crystallography, X-Ray; D008969:Molecular Sequence Data; D011485:Protein Binding; D017510:Protein Folding; D054730:Protein Interaction Domains and Motifs; D012342:RNA, Small Nuclear / Q000378:metabolism; D016914:Ribonuclease H / Q000737:chemistry / Q000378:metabolism; D017414:Ribonucleoprotein, U4-U6 Small Nuclear; D017415:Ribonucleoprotein, U5 Small Nuclear; D012269:Ribosomal Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D016415:Sequence Alignment; D017381:Spliceosomes / Q000378:metabolism
chemical_list: C077018:PRP8 protein, S cerevisiae; D012342:RNA, Small Nuclear; D017414:Ribonucleoprotein, U4-U6 Small Nuclear; D017415:Ribonucleoprotein, U5 Small Nuclear; D012269:Ribosomal Proteins; D029701:Saccharomyces cerevisiae Proteins; C405482:U4 small nuclear RNA; C405486:U6 small nuclear RNA; D016914:Ribonuclease H
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