Abstract
The ribosome undergoes pronounced periodic conformational changes during protein synthesis. Of particular importance are those occurring around the decoding site, the region of the 16 S rRNA interacting with the mRNA-(tRNA)(2) complex. We have incorporated structural information from X-ray crystallography and nuclear magnetic resonance into cryo-electron microscopic maps of ribosomal complexes designed to capture structural changes at the translocation step of the polypeptide elongation cycle. The A-site region of the decoding site actively participates in the translocation of the tRNA from the A to the P-site upon GTP hydrolysis by elongation factor G, shifting approximately 8 A toward the P-site. This implies that elongation factor G actively pushes both the decoding site and the mRNA/tRNA complex during translocation.
Copyright 2000 Academic Press.
Publication types
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Research Support, U.S. Gov't, P.H.S.
MeSH terms
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Base Sequence
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Binding Sites
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Cryoelectron Microscopy
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Crystallography, X-Ray
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Escherichia coli / chemistry
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Escherichia coli / genetics*
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Guanosine Diphosphate / metabolism
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Guanosine Triphosphate / analogs & derivatives*
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Guanosine Triphosphate / metabolism
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Hydrolysis
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Models, Molecular
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Nuclear Magnetic Resonance, Biomolecular
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Nucleic Acid Conformation
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Peptide Chain Elongation, Translational*
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Peptide Elongation Factor G / metabolism
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Protein Conformation
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RNA, Ribosomal, 16S / chemistry*
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RNA, Ribosomal, 16S / genetics
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RNA, Ribosomal, 16S / metabolism*
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RNA, Transfer / chemistry
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RNA, Transfer / genetics
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RNA, Transfer / metabolism*
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Ribosomes / chemistry
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Ribosomes / genetics
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Ribosomes / metabolism*
Substances
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Peptide Elongation Factor G
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RNA, Ribosomal, 16S
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Guanosine Diphosphate
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5'-guanylylmethylenebisphosphonate
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Guanosine Triphosphate
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RNA, Transfer