title: Decoding at the ribosomal A site: antibiotics, misreading and energy of aminoacyl-tRNA binding.
abstract: The binding of Phe-tRNAPhe at the programmed ribosomal A site has been investigated using antibiotics that influence this binding in different ways. The adhesion of Phe-tRNAPhe, the consumption of GTP and the extent of the peptidyl transfer reaction were monitored. All of the five known misreading-inducing antibiotics that were tested stabilised the binding of Phe-tRNAPhe after its affixture to the A site by EF-Tu with GTP hydrolysis. The stabilisation was sufficient to overcome a single mismatch in the codon-anticodon interaction. Combinations of stabilising and destabilising influences were found to be additive, thus supporting the concepts: (1) that there is a 'correct' binding energy for aminoacyl tRNA in the A site, whose reduction hampers polypeptide synthesis and whose increase makes it inaccurate by by-passing proofreading; and (2) that the different antibiotics affect the bound aminoacyl tRNA at different points.
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D003062:Codon; D004926:Escherichia coli / Q000378:metabolism; D010455:Peptides / Q000378:metabolism; D014176:Protein Biosynthesis / Q000187:drug effects*; D012333:RNA, Messenger; D012345:RNA, Transfer, Amino Acid-Specific / Q000378:metabolism*; D012270:Ribosomes / Q000187:drug effects / Q000378:metabolism*
chemical_list: D000900:Anti-Bacterial Agents; D003062:Codon; D010455:Peptides; D012333:RNA, Messenger; D012345:RNA, Transfer, Amino Acid-Specific