title: Yeast prions: could they be exaptations? The URE2/[URE3] system in Kluyveromyces lactis.
abstract: We examined aspects of the URE2/[URE3] prion system in Kluyveromyces lactis, which lies on a different evolutionary branch from Saccharomyces. We first analysed the polymorphism of the prion-forming domain in 38 strains. Considerable differences were found between these two genera, with little variation within K. lactis. We then analysed the regulatory function of Ure2p, using a deletion of URE2. We assessed the deregulation of two reporter genes: DAL5 and GDH2. Both were derepressed in the mutant strain, as in Saccharomyces. Finally, we tried to obtain the [URE3] prion from K. lactis. Despite the use of many different experimental conditions, we were unable to obtain a prion from Ure2p. This finding calls into question the extent to which the prion form of Ure2p may be considered an evolutionary adaptation, instead suggesting that an exaptation phenomenon may be more likely than a continuous selection history.
authors.affiliation: Université de Lyon, Université Lyon 1, Génétique Moléculaire des levures, UMR5240, Villeurbanne, France.
authors.forename: Rim Al
authors.initials: RA
authors.lastname: Safadi
authors.forename: Nicolas
authors.initials: N
authors.lastname: Talarek
authors.forename: Noémie
authors.initials: N
authors.lastname: Jacques
authors.forename: Michel
authors.initials: M
authors.lastname: Aigle
mesh_terms: D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism*; D017930:Genes, Reporter; D005979:Glutathione Peroxidase / Q000235:genetics / Q000378:metabolism*; D007716:Kluyveromyces / Q000201:enzymology*; D010641:Phenotype; D011110:Polymorphism, Genetic; D011328:Prions / Q000235:genetics / Q000378:metabolism*; D012641:Selection, Genetic; D017384:Sequence Deletion
chemical_list: D005656:Fungal Proteins; D011328:Prions; D005979:Glutathione Peroxidase