The DExH box protein Suv3p is a component of a yeast mitochondrial 3'-to-5' exoribonuclease that suppresses group I intron toxicity.
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.
Margossian
S P
SP
Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas 75235, USA.
Li
H
H
Zassenhaus
H P
HP
Butow
R A
RA
D001483:Base Sequence; D053487:DEAD-box RNA Helicases; D004271:DNA, Fungal / Q000032:analysis; D005091:Exons / Q000235:genetics; D005095:Exoribonucleases / Q000302:isolation & purification / Q000378:metabolism*; D005656:Fungal Proteins / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D007438:Introns / Q000235:genetics; D008928:Mitochondria / Q000201:enzymology*; D008969:Molecular Sequence Data; D012313:RNA / Q000378:metabolism; D020365:RNA Helicases; D012316:RNA Nucleotidyltransferases / Q000302:isolation & purification / Q000378:metabolism*; D012326:RNA Splicing / Q000502:physiology*; D012331:RNA, Fungal / Q000032:analysis / Q000096:biosynthesis / Q000378:metabolism; D000077278:RNA, Mitochondrial; D012335:RNA, Ribosomal / Q000096:biosynthesis / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000096:biosynthesis / Q000302:isolation & purification; D012441:Saccharomyces cerevisiae / Q000201:enzymology; D029701:Saccharomyces cerevisiae Proteins
D004271:DNA, Fungal; D005656:Fungal Proteins; D012331:RNA, Fungal; D000077278:RNA, Mitochondrial; D012335:RNA, Ribosomal; D011993:Recombinant Fusion Proteins; D029701:Saccharomyces cerevisiae Proteins; D012313:RNA; D012316:RNA Nucleotidyltransferases; D005095:Exoribonucleases; C075918:SUV3 protein, S cerevisiae; D053487:DEAD-box RNA Helicases; D020365:RNA Helicases