The essential WD-repeat protein Rsa4p is required for rRNA processing and intra-nuclear transport of 60S ribosomal subunits

Nucleic Acids Res. 2005 Oct 12;33(18):5728-39. doi: 10.1093/nar/gki887. Print 2005.

Abstract

We report the characterization of a novel factor, Rsa4p (Ycr072cp), which is essential for the synthesis of 60S ribosomal subunits. Rsa4p is a conserved WD-repeat protein that seems to localize in the nucleolus. In vivo depletion of Rsa4p results in a deficit of 60S ribosomal subunits and the appearance of half-mer polysomes. Northern hybridization and primer extension analyses of pre-rRNA and mature rRNAs show that depletion of Rsa4p leads to the accumulation of the 27S, 25.5S and 7S pre-rRNAs, resulting in a reduction of the mature 25S and 5.8S rRNAs. Pulse-chase analyses of pre-rRNA processing reveal that, at least, this is due to a strong delay in the maturation of 27S pre-rRNA intermediates to mature 25S rRNA. Furthermore, depletion of Rsa4p inhibited the release of the pre-60S ribosomal particles from the nucleolus to the nucleoplasm, as judged by the predominantly nucleolar accumulation of the large subunit Rpl25-eGFP reporter construct. We propose that Rsa4p associates early with pre-60S ribosomal particles and provides a platform of interaction for correct processing of rRNA precursors and nucleolar release of 60S ribosomal subunits.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Motifs
  • Amino Acid Sequence
  • Biological Transport
  • Cell Nucleolus / chemistry
  • Cell Nucleolus / metabolism
  • Cell Nucleus / metabolism*
  • Conserved Sequence
  • Gene Expression Regulation
  • Molecular Sequence Data
  • RNA Precursors / metabolism
  • RNA Processing, Post-Transcriptional*
  • RNA, Ribosomal / metabolism*
  • Ribosomal Proteins / analysis
  • Ribosomal Proteins / genetics
  • Ribosomal Proteins / physiology*
  • Ribosomes / metabolism*
  • Saccharomyces cerevisiae / genetics
  • Saccharomyces cerevisiae / metabolism*
  • Saccharomyces cerevisiae Proteins / analysis
  • Saccharomyces cerevisiae Proteins / genetics
  • Saccharomyces cerevisiae Proteins / physiology*

Substances

  • RNA Precursors
  • RNA, Ribosomal
  • Ribosomal Proteins
  • Rsa4 protein, S cerevisiae
  • Saccharomyces cerevisiae Proteins