Structural and Functional Insights into Saccharomyces cerevisiae Tpa1, a Putative Prolylhydroxylase Influencing Translation Termination and Transcription.
Fiche publication
Date publication
octobre 2010
Auteurs
Membres identifiés du Cancéropôle Est :
Dr SERAPHIN Bertrand
Tous les auteurs :
Henri J, Rispal D, Bayart E, van Tilbeurgh H, Seraphin B, Graille M
Lien Pubmed
Résumé
Efficiency of translation termination relies on the specific recognition of the three stop codons by the eukaryotic translation termination factor cRF1. To date only a few proteins are known to be involved in translation termination in eukaryotes. Saccharomyces cerevisiae Tpa1, a largely conserved but uncharacterized protein, has been described to associate with a messenger ribonucleoprotein complex located at the 3' end of mRNAs that contains at least eRF1, eRF3, and Pab1. Deletion of the TPA1 gene results in a decrease of translation termination efficacy and an increase in mRNAs half-lives and longer mRNA poly(A) tails. In parallel, Schizosaccharomyces pombe Ofd1, a Tpa1 ortholog, and its partner Nro1 have been implicated in the regulation of the stability of a transcription factor that regulates genes essential for the cell response to hypoxia. To gain insight into Tpa1/Ofd1 function, we have solved the crystal structure of S. cerevisiae Tpa1 protein. This protein is composed of two equivalent domains with the double-stranded beta-helix fold. The N-terminal domain displays a highly conserved active site with strong similarities with prolyl-4-hydroxylases. Further functional studies show that the integrity of Tpa1 active site as well as the presence of Yor051c/Ett1 (the S. cerevisiae Nro1 ortholog) are essential for correct translation termination. In parallel, we show that Tpa1 represses the expression of genes regulated by Hap1, a transcription factor involved in the response to levels of heme and oxygen. Altogether, our results support that Tpa1 is a putative enzyme acting as an oxygen sensor and influencing several distinct regulatory pathways.
Référence
J Biol Chem. 2010 Oct 1;285(40):30767-78