Abstract
A structural and mechanistic explanation for the selection of tRNAs by the ribosome has been elusive. Here, we report crystal structures of the 30S ribosomal subunit with codon and near-cognate tRNA anticodon stem loops bound at the decoding center and compare affinities of equivalent complexes in solution. In ribosomal interactions with near-cognate tRNA, deviation from Watson-Crick geometry results in uncompensated desolvation of hydrogen-bonding partners at the codon-anticodon minor groove. As a result, the transition to a closed form of the 30S induced by cognate tRNA is unfavorable for near-cognate tRNA unless paromomycin induces part of the rearrangement. We conclude that stabilization of a closed 30S conformation is required for tRNA selection, and thereby structurally rationalize much previous data on translational fidelity.
Publication types
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Comparative Study
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Research Support, Non-U.S. Gov't
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Research Support, U.S. Gov't, P.H.S.
MeSH terms
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Anti-Bacterial Agents / metabolism
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Anti-Bacterial Agents / pharmacology
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Anticodon / chemistry
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Anticodon / metabolism
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Base Pairing
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Binding, Competitive
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Codon / chemistry
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Codon / metabolism
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Crystallography, X-Ray
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Hydrogen Bonding
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Models, Molecular
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Nucleic Acid Conformation
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Paromomycin / metabolism
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Paromomycin / pharmacology
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RNA, Bacterial / chemistry
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RNA, Bacterial / metabolism
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RNA, Ribosomal, 16S / chemistry
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RNA, Ribosomal, 16S / metabolism
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RNA, Transfer / chemistry*
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RNA, Transfer / metabolism*
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RNA, Transfer, Phe / chemistry
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RNA, Transfer, Phe / metabolism
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Ribosomes / chemistry
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Ribosomes / metabolism*
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Structure-Activity Relationship
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Thermodynamics
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Thermus thermophilus
Substances
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Anti-Bacterial Agents
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Anticodon
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Codon
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RNA, Bacterial
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RNA, Ribosomal, 16S
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RNA, Transfer, Phe
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Paromomycin
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RNA, Transfer
Associated data
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PDB/1N32
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PDB/1N33
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PDB/1N34
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PDB/1N36