Abstract
Recognition of a start codon by the initiator aminoacyl-tRNA determines the reading frame of messenger RNA (mRNA) translation by the ribosome. In eukaryotes, the GTPase eIF5B collaborates in the correct positioning of the initiator Met-tRNAiMet on the ribosome in the later stages of translation initiation, gating entrance into elongation. Leveraging the long residence time of eIF5B on the ribosome recently identified by single-molecule fluorescence measurements, we determine the cryoEM structure of the naturally long-lived ribosome complex with eIF5B and Met-tRNAiMet immediately before transition into elongation. The structure uncovers an unexpected, eukaryotic specific and dynamic fidelity checkpoint implemented by eIF5B in concert with components of the large ribosomal subunit.
Publication types
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Research Support, N.I.H., Extramural
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Research Support, N.I.H., Intramural
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Research Support, Non-U.S. Gov't
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Video-Audio Media
MeSH terms
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Acylation
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Anticodon
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Cryoelectron Microscopy
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Eukaryotic Initiation Factors / chemistry*
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Eukaryotic Initiation Factors / genetics
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Eukaryotic Initiation Factors / metabolism*
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Guanosine Diphosphate / metabolism
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Models, Molecular
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Nucleic Acid Conformation
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Peptide Chain Elongation, Translational*
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Peptide Chain Initiation, Translational*
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RNA, Transfer, Met / chemistry
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RNA, Transfer, Met / metabolism
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Ribosome Subunits, Large / chemistry
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Ribosome Subunits, Large / genetics
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Ribosome Subunits, Large / metabolism*
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Ribosome Subunits, Large, Eukaryotic
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Ribosome Subunits, Small, Eukaryotic
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Saccharomyces cerevisiae / genetics
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Saccharomyces cerevisiae / metabolism
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Saccharomyces cerevisiae Proteins / chemistry
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Saccharomyces cerevisiae Proteins / genetics
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Saccharomyces cerevisiae Proteins / metabolism
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Serine / metabolism
Substances
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Anticodon
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Eukaryotic Initiation Factors
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RNA, Transfer, Met
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Saccharomyces cerevisiae Proteins
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eukaryotic initiation factor-5B
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Guanosine Diphosphate
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Serine