title: The iron-sulphur protein RNase L inhibitor functions in translation termination.
abstract: The iron-sulphur (Fe-S)-containing RNase L inhibitor (Rli1) is involved in ribosomal subunit maturation, transport of both ribosomal subunits to the cytoplasm, and translation initiation through interaction with the eukaryotic initiation factor 3 (eIF3) complex. Here, we present a new function for Rli1 in translation termination. Through co-immunoprecipitation experiments, we show that Rli1 interacts physically with the translation termination factors eukaryotic release factor 1 (eRF1)/Sup45 and eRF3/Sup35 in Saccharomyces cerevisiae. Genetic interactions were uncovered between a strain depleted for Rli1 and sup35-21 or sup45-2. Furthermore, we show that downregulation of RLI1 expression leads to defects in the recognition of a stop codon, as seen in mutants of other termination factors. By contrast, RLI1 overexpression partly suppresses the read-through defects in sup45-2. Interestingly, we find that although the Fe-S cluster is not required for the interaction of Rli1 with eRF1 or its other interacting partner, Hcr1, from the initiation complex eIF3, it is required for its activity in translation termination; an Fe-S cluster mutant of RLI1 cannot suppress the read-through defects of sup45-2.
authors.affiliation: Abteilung für Molekulare Strukturbiologie, Institut für Mikrobiologie und Genetik, Göttinger Zentrum für Molekulare Biowissenschaften, Georg-August-Universität Göttingen, Göttingen, Germany.
authors.forename: Sohail
authors.initials: S
authors.lastname: Khoshnevis
authors.forename: Thomas
authors.initials: T
authors.lastname: Gross
authors.forename: Carmen
authors.initials: C
authors.lastname: Rotte
authors.forename: Claudia
authors.initials: C
authors.lastname: Baierlein
authors.forename: Ralf
authors.initials: R
authors.lastname: Ficner
authors.forename: Heike
authors.initials: H
authors.lastname: Krebber
mesh_terms: D018528:ATP-Binding Cassette Transporters / Q000378:metabolism*; D003062:Codon; D004722:Endoribonucleases / Q000009:adverse effects* / Q000378:metabolism*; D005656:Fungal Proteins / Q000378:metabolism; D005816:Genetic Complementation Test; D047468:Immunoprecipitation; D007501:Iron / Q000378:metabolism*; D007506:Iron-Sulfur Proteins / Q000378:metabolism*; D010454:Peptide Termination Factors / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000235:genetics; D029701:Saccharomyces cerevisiae Proteins / Q000378:metabolism*; D013696:Temperature; D014178:Translocation, Genetic; D020798:Two-Hybrid System Techniques; D001616:beta-Galactosidase / Q000378:metabolism
chemical_list: D018528:ATP-Binding Cassette Transporters; D003062:Codon; D005656:Fungal Proteins; D007506:Iron-Sulfur Proteins; D010454:Peptide Termination Factors; C492990:RLI1 protein, S cerevisiae; C068068:SUP35 protein, S cerevisiae; C080775:SUP45 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D007501:Iron; D004722:Endoribonucleases; C031956:2-5A-dependent ribonuclease; D001616:beta-Galactosidase