Translational readthrough of the PDE2 stop codon modulates cAMP levels in Saccharomyces cerevisiae.
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.
Namy
Olivier
O
Laboratoire de génétique moléculaire de la traduction, Institut de Génétique et Microbiologie, Université Paris-Sud, Orsay, France.
Duchateau-Nguyen
Guillemette
G
Rousset
Jean-Pierre
JP
D018388:Codon, Terminator; D000242:Cyclic AMP / Q000378:metabolism*; D054678:Cyclic Nucleotide Phosphodiesterases, Type 2; D009154:Mutation; D016366:Open Reading Frames; D010727:Phosphoric Diester Hydrolases / Q000235:genetics* / Q000378:metabolism; D014176:Protein Biosynthesis; D012441:Saccharomyces cerevisiae / Q000235:genetics* / Q000378:metabolism
D018388:Codon, Terminator; D000242:Cyclic AMP; D010727:Phosphoric Diester Hydrolases; D054678:Cyclic Nucleotide Phosphodiesterases, Type 2