The 3′ end of yeast 5.8S rRNA is generated by an exonuclease processing mechanism

Philip Mitchell*, Elisabeth Petfalski, David Tollervey

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

Eukaryotic rRNAs (with the exception of 5S rRNA) are synthesized from a contiguous pie-rRNA precursor by a complex series of processing reactions. Final maturation of yeast 5.8S rRNA involves processing of a 3′-extended, 7S precursor that contains ∼140 nucleotides of the internal transcribed spacer 2 (ITS2) region. In yeast strains carrying the temperature-sensitive (ts) rrp4-1 mutation, 5.8S rRNA species were observed with 3′ extensions of variable length extending up to the 3′ end of the 7S pre-rRNA. These 3′-extended 5.8S rRNA species were observed at low levels in rrp4-1 strains under conditions permissive for growth and increased in abundance upon transfer to the nonpermissive temperature. The RRP4 gene was cloned by complementation of the ts growth phenotype of rrp4-1 strains. RRP4 encodes an essential protein of 39-kD predicted molecular mass. Immunoprecipitated Rrp4p exhibited a 3′ → 5′ exoribonuclease activity in vitro that required RNA with a 3′-terminal hydroxyl group and released nucleoside 5′ monophosphates. We conclude that the 7S pre-rRNA is processed to 5.8S rRNA by a 3′ → 5′ exonuclease activity involving Rrp4p. Homologs of Rrp4p are found in both humans and the fission yeast Schizosaccaromyces pombe (43% and 52% identity, respectively), suggesting that the mechanism of 5.8S rRNA 3′ end formation has been conserved throughout eukaryotes.

Original languageEnglish
Pages (from-to)502-513
Number of pages12
JournalGenes and Development
Volume10
Issue number4
DOIs
Publication statusPublished - 15 Feb 1996

Keywords

  • 3′ → 5′ exonuclease
  • RNA processing
  • rRNA
  • RRP4 gene
  • S. cerevisiae

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