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Conformational flexibility required for class I release factor function
Author(s) -
Gautam Amit,
Eyler Daniel E,
Green Rachel
Publication year - 2007
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.21.5.a647-a
Subject(s) - peptidyl transferase , peptide bond , chemistry , transfer rna , mutant , ribosome , tripeptide , stereochemistry , peptide , biochemistry , biophysics , microbiology and biotechnology , biology , rna , gene
Bacterial release factors (RFs) bind to ribosomes stalled at stop codons and stimulate hydrolysis of the peptidyl‐tRNA bond. A universally conserved GGQ motif in the RF reaches into the peptidyl transferase center to promote peptide release. A separate motif, the tripeptide anticodon, interacts with the stop codon. In the crystal structures of bacterial RFs, these two motifs are approximately 20 A apart. On the ribosome, however, the decoding site and the peptidyl transferase center are 70 A apart. Thus, in order to simultaneously bind both sites, the RF must adopt a significantly different conformation in solution. We have engineered RF mutants that can form disulfide bonds while in the crystal conformation. Under reducing conditions, where the disulfide bond is disrupted, these mutants possess wild‐type release activity. The mutant RFs exhibit diminished release activity under oxidizing conditions. These results indicate that the crystal structure conformation of bacterial class I RFs is inactive for release. Funded by HHMI