Abstract
The Ski2-like RNA helicase Brr2 is a core component of the spliceosome that must be tightly regulated to ensure correct timing of spliceosome activation. Little is known about mechanisms of regulation of Ski2-like helicases by protein cofactors. Here we show by crystal structure and biochemical analyses that the Prp8 protein, a major regulator of the spliceosome, can insert its C-terminal tail into Brr2's RNA-binding tunnel, thereby intermittently blocking Brr2's RNA-binding, adenosine triphosphatase, and U4/U6 unwinding activities. Inefficient Brr2 repression is the only recognizable phenotype associated with certain retinitis pigmentosa-linked Prp8 mutations that map to its C-terminal tail. Our data show how a Ski2-like RNA helicase can be reversibly inhibited by a protein cofactor that directly competes with RNA substrate binding.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Amino Acid Motifs
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Amino Acid Sequence
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Binding, Competitive*
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Carrier Proteins / genetics
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Carrier Proteins / metabolism*
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Humans
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Molecular Sequence Data
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Mutation
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Protein Structure, Tertiary
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RNA / metabolism*
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RNA Helicases / metabolism
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RNA-Binding Proteins
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Ribonucleoprotein, U4-U6 Small Nuclear / metabolism
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Ribonucleoprotein, U5 Small Nuclear / metabolism
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Ribonucleoproteins, Small Nuclear / antagonists & inhibitors*
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Ribonucleoproteins, Small Nuclear / chemistry
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Ribonucleoproteins, Small Nuclear / metabolism*
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Saccharomyces cerevisiae Proteins / metabolism
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Spliceosomes / metabolism*
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Substrate Specificity
Substances
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Carrier Proteins
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PRP8 protein, S cerevisiae
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PRPF8 protein, human
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RNA-Binding Proteins
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Ribonucleoprotein, U4-U6 Small Nuclear
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Ribonucleoprotein, U5 Small Nuclear
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Ribonucleoproteins, Small Nuclear
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SNRNP200 protein, human
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Saccharomyces cerevisiae Proteins
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RNA
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BRR2 protein, S cerevisiae
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RNA Helicases