title: ATP-dependent unwinding of U4/U6 snRNAs by the Brr2 helicase requires the C terminus of Prp8.
abstract: The spliceosome is a highly dynamic machine requiring multiple RNA-dependent ATPases of the DExD/H-box family. A fundamental unanswered question is how their activities are regulated. Brr2 function is necessary for unwinding the U4/U6 duplex, a step essential for catalytic activation of the spliceosome. Here we show that Brr2-dependent dissociation of U4/U6 snRNAs in vitro is activated by a fragment from the C terminus of the U5 snRNP protein Prp8. In contrast to its helicase-stimulating activity, this fragment inhibits Brr2 U4/U6-dependent ATPase activity. Notably, U4/U6 unwinding activity is not stimulated by fragments carrying alleles of prp8 that in humans confers an autosomal dominant form of retinitis pigmentosa. Because Brr2 activity must be restricted to prevent premature catalytic activation, our results have important implications for fidelity maintenance in the spliceosome.
authors.affiliation: Department of Biochemistry and Biophysics, University of California, San Francisco, 600 16th Street, California 94143, USA.
authors.forename: Corina
authors.initials: C
authors.lastname: Maeder
authors.forename: Alan K
authors.initials: AK
authors.lastname: Kutach
authors.forename: Christine
authors.initials: C
authors.lastname: Guthrie
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism*; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism; D005799:Genes, Dominant; D006801:Humans; D009154:Mutation; D010446:Peptide Fragments / Q000737:chemistry / Q000378:metabolism; D011489:Protein Denaturation; D020365:RNA Helicases / Q000235:genetics / Q000378:metabolism*; D012326:RNA Splicing / Q000235:genetics; D012331:RNA, Fungal / Q000235:genetics; D016601:RNA-Binding Proteins; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism; D012174:Retinitis Pigmentosa / Q000235:genetics; D017414:Ribonucleoprotein, U4-U6 Small Nuclear / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D017415:Ribonucleoprotein, U5 Small Nuclear; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000254:growth & development / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D017381:Spliceosomes / Q000235:genetics
chemical_list: D002352:Carrier Proteins; C077018:PRP8 protein, S cerevisiae; C115374:PRPF8 protein, human; D010446:Peptide Fragments; D012331:RNA, Fungal; D016601:RNA-Binding Proteins; D011994:Recombinant Proteins; D017414:Ribonucleoprotein, U4-U6 Small Nuclear; D017415:Ribonucleoprotein, U5 Small Nuclear; D029701:Saccharomyces cerevisiae Proteins; D000255:Adenosine Triphosphate; C104158:BRR2 protein, S cerevisiae; D020365:RNA Helicases