Visualization of tRNA movements on the Escherichia coli 70S ribosome during the elongation cycle |
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Authors: | Agrawal R K Spahn C M Penczek P Grassucci R A Nierhaus K H Frank J |
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Institution: | Wadsworth Center, Department of Biomedical Sciences, State University of New York, Albany, New York 12201, USA. |
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Abstract: | Three-dimensional cryomaps have been reconstructed for tRNA-ribosome complexes in pre- and posttranslocational states at 17-A resolution. The positions of tRNAs in the A and P sites in the pretranslocational complexes and in the P and E sites in the posttranslocational complexes have been determined. Of these, the P-site tRNA position is the same as seen earlier in the initiation-like fMet-tRNA(f)(Met)-ribosome complex, where it was visualized with high accuracy. Now, the positions of the A- and E-site tRNAs are determined with similar accuracy. The positions of the CCA end of the tRNAs at the A site are different before and after peptide bond formation. The relative positions of anticodons of P- and E-site tRNAs in the posttranslocational state are such that a codon-anticodon interaction at the E site appears feasible. |
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Keywords: | ribosomes protein synthesis tRNA-binding sites cryoelectron microscopy elongation cycle |
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