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Substrate Selection and Peptide Bond Formation by the Ribosome
Author(s) -
Rodnina Marina V.,
Kothe Ute,
Beringer Malte,
Gromadski Kirill B.,
Bieling Peter
Publication year - 2006
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.20.4.a35-d
Subject(s) - transfer rna , ribosome , p site , chemistry , ternary complex , a site , t arm , genetic code , ribosomal rna , biophysics , stereochemistry , biology , biochemistry , rna , amino acid , binding site , enzyme , gene
The ribosome recognizes aminoacyl‐tRNA through shape discrimination of the codon‐anticodon duplex and regulates the rates of GTP hydrolysis by EF‐Tu and aa‐tRNA accommodation in the A site by an induced fit mechanism. Initial recognition of ternary complexes is achieved through interactions between EF‐Tu and the C‐terminal domain of the ribosomal protein L12. Any mismatch in the codon‐anticodon complex results in a uniformly 1000‐fold faster dissociation of tRNA from the ribosome and slower forward reactions, essentially independently of the nature and position of the mismatch. These data provide evidence that high fidelity of tRNA selection is achieved by a ribosome switch between accepting and rejecting modes regardless of thermodynamic stability of the codon‐anticodon complexes or their docking partners at the decoding site. The catalysis of peptidyl transfer reaction does not require ribosome groups ionizing at neutral pH, indicating that the ribosome is a poor general acid‐base catalyst. Instead, most of the catalytic power of the ribosome must result from the binding of tRNA substrates in the active site by interactions with rRNA, providing a preorganized environment facilitating the reaction.