Identification of stop codon readthrough genes in Saccharomyces cerevisiae

Nucleic Acids Res. 2003 May 1;31(9):2289-96. doi: 10.1093/nar/gkg330.

Abstract

We specifically sought genes within the yeast genome controlled by a non-conventional translation mechanism involving the stop codon. For this reason, we designed a computer program using the yeast database genomic regions, and seeking two adjacent open reading frames separated only by a unique stop codon (called SORFs). Among the 58 SORFs identified, eight displayed a stop codon bypass level ranging from 3 to 25%. For each of the eight sequences, we demonstrated the presence of a poly(A) mRNA. Using isogenic [PSI(+)] and [psi(-)] yeast strains, we showed that for two of the sequences the mechanism used is a bona fide readthrough. However, the six remaining sequences were not sensitive to the PSI state, indicating either a translation termination process independent of eRF3 or a new stop codon bypass mechanism. Our results demonstrate that the presence of a stop codon in a large ORF may not always correspond to a sequencing error, or a pseudogene, but can be a recoding signal in a functional gene. This emphasizes that genome annotation should take into account the fact that recoding signals could be more frequently used than previously expected.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Base Sequence
  • Codon, Terminator / genetics*
  • Genes, Fungal / genetics*
  • Lac Operon / genetics
  • Luciferases / genetics
  • Luciferases / metabolism
  • Open Reading Frames / genetics
  • Plasmids / genetics
  • Protein Biosynthesis
  • RNA, Messenger / genetics
  • RNA, Messenger / metabolism
  • Recombinant Fusion Proteins / genetics
  • Recombinant Fusion Proteins / metabolism
  • Saccharomyces cerevisiae / genetics*
  • Sequence Homology, Nucleic Acid
  • Software*
  • beta-Galactosidase / genetics
  • beta-Galactosidase / metabolism

Substances

  • Codon, Terminator
  • RNA, Messenger
  • Recombinant Fusion Proteins
  • Luciferases
  • beta-Galactosidase