The products of the SUP45 (eRF1) and SUP35 genes interact to mediate translation termination in Saccharomyces cerevisiae

EMBO J. 1995 Sep 1;14(17):4365-73.

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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Base Sequence
  • Blotting, Western
  • Fungal Proteins / genetics
  • Fungal Proteins / isolation & purification
  • Fungal Proteins / metabolism*
  • Genes, Fungal*
  • Histidine
  • Molecular Sequence Data
  • Multigene Family*
  • Oligodeoxyribonucleotides
  • Peptide Chain Termination, Translational / genetics*
  • Peptide Termination Factors*
  • Plasmids
  • Prions*
  • Protein Binding
  • Recombinant Proteins / biosynthesis
  • Recombinant Proteins / isolation & purification
  • Recombinant Proteins / metabolism
  • Restriction Mapping
  • Saccharomyces cerevisiae / genetics*
  • Saccharomyces cerevisiae / metabolism*
  • Saccharomyces cerevisiae Proteins*
  • Suppression, Genetic

Substances

  • Fungal Proteins
  • Oligodeoxyribonucleotides
  • Peptide Termination Factors
  • Prions
  • Recombinant Proteins
  • SUP35 protein, S cerevisiae
  • SUP45 protein, S cerevisiae
  • Saccharomyces cerevisiae Proteins
  • Histidine