Translational readthrough of the PDE2 stop codon modulates cAMP levels in Saccharomyces cerevisiae

Mol Microbiol. 2002 Feb;43(3):641-52. doi: 10.1046/j.1365-2958.2002.02770.x.


The efficiency of translation termination in yeast can vary several 100-fold, depending on the context around the stop codon. We performed a computer analysis designed to identify yeast open reading frames (ORFs) containing a readthrough motif surrounding the termination codon. Eight ORFs were found to display inefficient stop codon recognition, one of which, PDE2, encodes the high-affinity cAMP phosphodiesterase. We demonstrate that Pde2p stability is very impaired by the readthrough-dependent extension of the protein. A 20-fold increase in readthrough of PDE2 was observed in a [PSI+] as compared with a [psi-] strain. Consistent with this observation, an important increase in cAMP concentration was observed in suppressor backgrounds. These results provide a molecular explanation for at least some of the secondary phenotypes associated with suppressor backgrounds.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Codon, Terminator*
  • Cyclic AMP / metabolism*
  • Cyclic Nucleotide Phosphodiesterases, Type 2
  • Mutation
  • Open Reading Frames
  • Phosphoric Diester Hydrolases / genetics*
  • Phosphoric Diester Hydrolases / metabolism
  • Protein Biosynthesis*
  • Saccharomyces cerevisiae / genetics*
  • Saccharomyces cerevisiae / metabolism


  • Codon, Terminator
  • Cyclic AMP
  • Phosphoric Diester Hydrolases
  • Cyclic Nucleotide Phosphodiesterases, Type 2