title: The products of the SUP45 (eRF1) and SUP35 genes interact to mediate translation termination in Saccharomyces cerevisiae.
abstract: The product of the yeast SUP45 gene (Sup45p) is highly homologous to the Xenopus eukaryote release factor 1 (eRF1), which has release factor activity in vitro. We show, using the two-hybrid system, that in Saccharomyces cerevisiae Sup45p and the product of the SUP35 gene (Sup35p) interact in vivo. The ability of Sup45p C-terminally tagged with (His)6 to specifically precipitate Sup35p from a cell lysate was used to confirm this interaction in vitro. Although overexpression of either the SUP45 or SUP35 genes alone did not reduce the efficiency of codon-specific tRNA nonsense suppression, the simultaneous overexpression of both the SUP35 and SUP45 genes in nonsense suppressor tRNA-containing strains produced an antisuppressor phenotype. These data are consistent with Sup35p and Sup45p forming a complex with release factor properties. Furthermore, overexpression of either Xenopus or human eRF1 (SUP45) genes also resulted in anti-suppression only if that strain was also overexpressing the yeast SUP35 gene. Antisuppression is a characteristic phenotype associated with overexpression of both prokaryote and mitochondrial release factors. We propose that Sup45p and Sup35p interact to form a release factor complex in yeast and that Sup35p, which has GTP binding sequence motifs in its C-terminal domain, provides the GTP hydrolytic activity which is a demonstrated requirement of the eukaryote translation termination reaction.
authors.affiliation: Research School of Biosciences, University of Kent, Canterbury, UK.
authors.forename: I
authors.initials: I
authors.lastname: Stansfield
authors.forename: K M
authors.initials: KM
authors.lastname: Jones
authors.forename: V V
authors.initials: VV
authors.lastname: Kushnirov
authors.forename: A R
authors.initials: AR
authors.lastname: Dagkesamanskaya
authors.forename: A I
authors.initials: AI
authors.lastname: Poznyakovski
authors.forename: S V
authors.initials: SV
authors.lastname: Paushkin
authors.forename: C R
authors.initials: CR
authors.lastname: Nierras
authors.forename: B S
authors.initials: BS
authors.lastname: Cox
authors.forename: M D
authors.initials: MD
authors.lastname: Ter-Avanesyan
authors.forename: M F
authors.initials: MF
authors.lastname: Tuite
mesh_terms: D000595:Amino Acid Sequence; D001483:Base Sequence; D015153:Blotting, Western; D005656:Fungal Proteins / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D005800:Genes, Fungal; D006639:Histidine; D008969:Molecular Sequence Data; D005810:Multigene Family; D009838:Oligodeoxyribonucleotides; D010443:Peptide Chain Termination, Translational / Q000235:genetics*; D010454:Peptide Termination Factors; D010957:Plasmids; D011328:Prions; D011485:Protein Binding; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000302:isolation & purification / Q000378:metabolism; D015183:Restriction Mapping; D012441:Saccharomyces cerevisiae / Q000235:genetics* / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins; D013489:Suppression, Genetic
chemical_list: D005656:Fungal Proteins; D009838:Oligodeoxyribonucleotides; D010454:Peptide Termination Factors; D011328:Prions; D011994:Recombinant Proteins; C068068:SUP35 protein, S cerevisiae; C080775:SUP45 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D006639:Histidine