Surveillance of nuclear-restricted pre-ribosomes within a subnucleolar region of Saccharomyces cerevisiae

C Dez, J Houseley, D Tollervey

Research output: Contribution to journalArticlepeer-review

Abstract

We previously hypothesized that HEAT-repeat (Huntington, elongation A subunit, TOR) ribosome synthesis factors function in ribosome export. We report that the HEAT-repeat protein Sda1p is a component of late 60S pre-ribosomes and is required for nuclear export of both ribosomal subunits. In strains carrying the ts-lethal sda1-2 mutation, pre-60S particles were rapidly degraded following transfer to 37 degrees C. Polyadenylated forms of the 27S pre-rRNA and the 25S rRNA were detected, suggesting the involvement of the Trf4p/Air/Mtr4p polyadenylation complex ( TRAMP). The absence of Trf4p suppressed polyadenylation and stabilized the pre-rRNA and rRNA. The absence of the nuclear exosome component Rrp6p also conferred RNA stabilization, with some hyperadenylation. We conclude that the nuclear-restricted pre-ribosomes are polyadenylated by TRAMP and degraded by the exosome. In sda1-2 strains at 37 degrees C, pre-40S and pre-60S ribosomes initially accumulated in the nucleoplasm, but then strongly concentrated in a subnucleolar focus, together with exosome and TRAMP components. Localization of pre-ribosomes to this focus was lost in sda1-2 strains lacking Trf4p or Rrp6p. We designate this nucleolar focus the No- body and propose that it represents a site of pre-ribosome surveillance.

Original languageEnglish
Pages (from-to)1534-1546
Number of pages13
JournalEMBO Journal
Volume25
Issue number7
DOIs
Publication statusPublished - 5 Apr 2006

Keywords

  • exosome
  • polyadenylation
  • ribosome synthesis

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