Mutations in elongation factor 1beta, a guanine nucleotide exchange factor, enhance translational fidelity.
Translation elongation factor 1beta (EF-1beta) is a member of the family of guanine nucleotide exchange factors, proteins whose activities are important for the regulation of G proteins critical to many cellular processes. EF-1beta is a highly conserved protein that catalyzes the exchange of bound GDP for GTP on EF-1alpha, a required step to ensure continued protein synthesis. In this work, we demonstrate that the highly conserved C-terminal region of Saccharomyces cerevisiae EF-1beta is sufficient for normal cell growth. This region of yeast and metazoan EF-1beta and the metazoan EF-1beta-like protein EF-1delta is highly conserved. Human EF-1beta, but not human EF-1delta, is functional in place of yeast EF-1beta, even though both EF-1beta and EF-1delta have previously been shown to have guanine nucleotide exchange activity in vitro. Based on the sequence and functional homology, mutagenesis of two C-terminal residues identical in all EF-1beta protein sequences was performed, resulting in mutants with growth defects and sensitivity to translation inhibitors. These mutants also enhance translational fidelity at nonsense codons, which correlates with a reduction in total protein synthesis. These results indicate the critical function of EF-1beta in regulating EF-1alpha activity, cell growth, translation rates, and translational fidelity.
Department of Molecular Genetics and Microbiology, UMDNJ Robert Wood Johnson Medical School, Piscataway, New Jersey, USA.
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Carr-Schmid
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Valente
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Loik
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Williams
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Starita
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D000483:Alleles; D000595:Amino Acid Sequence; D003062:Codon / Q000235:genetics; D018388:Codon, Terminator; D016368:Frameshift Mutation; D005656:Fungal Proteins / Q000235:genetics / Q000502:physiology*; D005816:Genetic Complementation Test; D006153:Guanosine Diphosphate / Q000378:metabolism; D006160:Guanosine Triphosphate / Q000378:metabolism*; D006801:Humans; D008969:Molecular Sequence Data; D009154:Mutation; D010441:Peptide Chain Elongation, Translational; D020648:Peptide Elongation Factor 1; D010445:Peptide Elongation Factors / Q000235:genetics / Q000502:physiology*; D014176:Protein Biosynthesis; D012331:RNA, Fungal / Q000235:genetics; D012441:Saccharomyces cerevisiae / Q000235:genetics* / Q000378:metabolism; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D013045:Species Specificity
D003062:Codon; D018388:Codon, Terminator; D005656:Fungal Proteins; D020648:Peptide Elongation Factor 1; D010445:Peptide Elongation Factors; D012331:RNA, Fungal; D006153:Guanosine Diphosphate; D006160:Guanosine Triphosphate