Abstract
The yeast mitochondrial protein Suv3p is a putative NTP-dependent RNA helicase. Here we report that in cells lacking Suv3p, there is an approximately 50-fold increase in the excised form of the group I intron omega of the mitochondrial 31S rRNA gene. Surprisingly, little mature 21S rRNA accumulates in those cells; instead, unligated 21S rRNA exons appear. Intron overaccumulation could lead to spliced exon reopening via a reaction known to be catalyzed by group I introns in vitro. We also show that Suv3p is a functional component of a novel mitochondrial NTP-dependent 3'-to-5' exoribonuclease activity that can degrade group I intron RNAs. These findings account for group I intron overaccumulation in cells lacking Suv3p and define a novel function for putative RNA helicases in direct RNA degradation.
Publication types
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Research Support, Non-U.S. Gov't
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Research Support, U.S. Gov't, Non-P.H.S.
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Research Support, U.S. Gov't, P.H.S.
MeSH terms
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Base Sequence
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DEAD-box RNA Helicases
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DNA, Fungal / analysis
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Exons / genetics
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Exoribonucleases / isolation & purification
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Exoribonucleases / metabolism*
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Fungal Proteins / genetics
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Fungal Proteins / isolation & purification
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Fungal Proteins / metabolism*
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Introns* / genetics
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Mitochondria / enzymology*
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Molecular Sequence Data
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RNA / metabolism
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RNA Helicases
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RNA Nucleotidyltransferases / isolation & purification
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RNA Nucleotidyltransferases / metabolism*
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RNA Splicing / physiology*
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RNA, Fungal / analysis
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RNA, Fungal / biosynthesis
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RNA, Fungal / metabolism
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RNA, Mitochondrial
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RNA, Ribosomal / biosynthesis
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RNA, Ribosomal / metabolism
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Recombinant Fusion Proteins / biosynthesis
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Recombinant Fusion Proteins / isolation & purification
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Saccharomyces cerevisiae / enzymology
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Saccharomyces cerevisiae Proteins*
Substances
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DNA, Fungal
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Fungal Proteins
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RNA, Fungal
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RNA, Mitochondrial
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RNA, Ribosomal
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Recombinant Fusion Proteins
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Saccharomyces cerevisiae Proteins
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RNA
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RNA Nucleotidyltransferases
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Exoribonucleases
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SUV3 protein, S cerevisiae
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DEAD-box RNA Helicases
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RNA Helicases