The eukaryote-specific N-terminal extension of ribosomal protein S31 contributes to the assembly and function of 40S ribosomal subunits

Nucleic Acids Res. 2016 Sep 19;44(16):7777-91. doi: 10.1093/nar/gkw641. Epub 2016 Jul 15.


The archaea-/eukaryote-specific 40S-ribosomal-subunit protein S31 is expressed as an ubiquitin fusion protein in eukaryotes and consists of a conserved body and a eukaryote-specific N-terminal extension. In yeast, S31 is a practically essential protein, which is required for cytoplasmic 20S pre-rRNA maturation. Here, we have studied the role of the N-terminal extension of the yeast S31 protein. We show that deletion of this extension partially impairs cell growth and 40S subunit biogenesis and confers hypersensitivity to aminoglycoside antibiotics. Moreover, the extension harbours a nuclear localization signal that promotes active nuclear import of S31, which associates with pre-ribosomal particles in the nucleus. In the absence of the extension, truncated S31 inefficiently assembles into pre-40S particles and two subpopulations of mature small subunits, one lacking and another one containing truncated S31, can be identified. Plasmid-driven overexpression of truncated S31 partially suppresses the growth and ribosome biogenesis defects but, conversely, slightly enhances the hypersensitivity to aminoglycosides. Altogether, these results indicate that the N-terminal extension facilitates the assembly of S31 into pre-40S particles and contributes to the optimal translational activity of mature 40S subunits but has only a minor role in cytoplasmic cleavage of 20S pre-rRNA at site D.

MeSH terms

  • Alleles
  • Aminoglycosides / pharmacology
  • Anti-Bacterial Agents / pharmacology
  • Cell Nucleolus / drug effects
  • Cell Nucleolus / metabolism
  • Mutation / genetics
  • Nuclear Localization Signals / metabolism
  • Phenotype
  • Polyribosomes / drug effects
  • Polyribosomes / metabolism
  • Protein Biosynthesis / drug effects
  • RNA Processing, Post-Transcriptional / drug effects
  • Ribosomal Proteins / metabolism*
  • Ribosome Subunits, Small, Eukaryotic / metabolism*
  • Saccharomyces cerevisiae / cytology
  • Saccharomyces cerevisiae / drug effects
  • Saccharomyces cerevisiae / growth & development
  • Saccharomyces cerevisiae / metabolism*
  • Saccharomyces cerevisiae Proteins / metabolism*


  • Aminoglycosides
  • Anti-Bacterial Agents
  • Nuclear Localization Signals
  • Ribosomal Proteins
  • Rps31 protein, S cerevisiae
  • Saccharomyces cerevisiae Proteins