A nuclear AAA-type ATPase (Rix7p) is required for biogenesis and nuclear export of 60S ribosomal subunits

EMBO J. 2001 Jul 16;20(14):3695-704. doi: 10.1093/emboj/20.14.3695.

Abstract

Ribosomal precursor particles are assembled in the nucleolus before export into the cytoplasm. Using a visual assay for nuclear accumulation of 60S subunits, we have isolated several conditional-lethal strains with defects in ribosomal export (rix mutants). Here we report the characterization of a mutation in an essential gene, RIX7, which encodes a novel member of the AAA ATPase superfamily. The rix7-1 temperature-sensitive allele carries a point mutation that causes defects in pre-rRNA processing, biogenesis of 60S ribosomal subunits, and their subsequent export into the cytoplasm. Rix7p, which associates with 60S ribosomal precursor particles, localizes throughout the nucleus in exponentially growing cells, but concentrates in the nucleolus in stationary phase cells. When cells resume growth upon shift to fresh medium, Rix7p-green fluorescent protein exhibits a transient perinuclear location. We propose that a nuclear AAA ATPase is required for restructuring nucleoplasmic 60S pre-ribosomal particles to make them competent for nuclear export.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adenosine Triphosphatases / genetics
  • Adenosine Triphosphatases / metabolism*
  • Base Sequence
  • Biological Transport
  • Cell Nucleolus / metabolism
  • Cell Nucleus / enzymology*
  • Cytoplasm / metabolism
  • DNA Primers
  • Green Fluorescent Proteins
  • Luminescent Proteins / metabolism
  • Mutation
  • Nuclear Proteins
  • RNA Processing, Post-Transcriptional / genetics
  • RNA, Ribosomal / metabolism
  • Recombinant Fusion Proteins / metabolism
  • Ribosomes / metabolism*
  • Saccharomyces cerevisiae / genetics
  • Saccharomyces cerevisiae / metabolism
  • Saccharomyces cerevisiae Proteins*

Substances

  • DNA Primers
  • Luminescent Proteins
  • Nuclear Proteins
  • RNA, Ribosomal
  • Recombinant Fusion Proteins
  • Saccharomyces cerevisiae Proteins
  • Green Fluorescent Proteins
  • Adenosine Triphosphatases
  • RIX7 protein, S cerevisiae