CORDIS provides links to public deliverables and publications of HORIZON projects.
Links to deliverables and publications from FP7 projects, as well as links to some specific result types such as dataset and software, are dynamically retrieved from OpenAIRE .
Exploitable results
The transcription activation sites (UAS) of SUP35 and SUP45 were mapped and characterised. In both cases they contain and Abf1p-site and a T-rich element which are usually present in promoter regions of yeast ribosomal protein genes. We showed that the regulation patterns of SUP35 and SUP45 transcripts are strikingly similar to those ribsomal genes. An unusual feature was found for the SUP35 gene: it harbors a cryptic internal promoter element.
Genetic and biochemical evidences obtained during this project suggest that SUP35 protein may adopt a specific self-propagating conformation, similarly to mammalian prions, giving rise to the cytoplasmically inherited suppressor determinant [PSI+]. We developed a cell-free assay to study the conversion of Sup35p from [psi-] cells to the prion-like [PSI+]-specific form. This technique allowed us to demonstrate the general similarity of yeast and mammalian prions and provided a new support for the "protein only" hypothesis for the inheritance of yeast [PSI+] phenotype. The mechanism of inhibition of [PSI+] prion propagation by the mutation in the N-terminus of Sup35p was studied. This work opens the way to investigate the structural rules defining the inhibitory potential of altered prion proteins.
We have demonstrated earlier that yeast Sup35 and Sup45 proteins interact to form a complex functional in termination of translation. In the present study two sites for Sup45p binding were localised within the Sup35p molecule. We have also demonstrated that binding of Sup45p and Sup35p is critical for the de novo appearing cells containing [PSI+] prion. The study of yeast [PSI+] prion also allowed us to demonstrate that prion phenomenon may represent a novel mechanism of regulation of gene expression at the post-translational level. This mechanism presumes that the N-terminal domain of Sup35p, which is responsible for the [PSI+]-dependent aggregation of the protein, may be regarded as a cis-acting repressor of the polypeptide chain release function of the Sup35p C-terminal domain. In addition, Sup35p N-terminal domain may act as a trans-acting repressor of another polypeptide chain release factor, Sup45p.
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