title: Tuning the affinity of aminoacyl-tRNA to elongation factor Tu for optimal decoding.
abstract: To better understand why aminoacyl-tRNAs (aa-tRNAs) have evolved to bind bacterial elongation factor Tu (EF-Tu) with uniform affinities, mutant tRNAs with differing affinities for EF-Tu were assayed for decoding on Escherichia coli ribosomes. At saturating EF-Tu concentrations, weaker-binding aa-tRNAs decode their cognate codons similarly to wild-type tRNAs. However, tighter-binding aa-tRNAs show reduced rates of peptide bond formation due to slow release from EF-Tu•GDP. Thus, the affinities of aa-tRNAs for EF-Tu are constrained to be uniform by their need to bind tightly enough to form the ternary complex but weakly enough to release from EF-Tu during decoding. Consistent with available crystal structures, the identity of the esterified amino acid and three base pairs in the T stem of tRNA combine to define the affinity of each aa-tRNA for EF-Tu, both off and on the ribosome.
authors.affiliation: Department of Molecular Biosciences, Northwestern University, Evanston, IL 60208, USA.
authors.forename: Jared M
authors.initials: JM
authors.lastname: Schrader
authors.forename: Stephen J
authors.initials: SJ
authors.lastname: Chapman
authors.forename: Olke C
authors.initials: OC
authors.lastname: Uhlenbeck
mesh_terms: D001483:Base Sequence; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism; D029968:Escherichia coli Proteins / Q000235:genetics / Q000378:metabolism*; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009154:Mutation; D009690:Nucleic Acid Conformation; D010444:Peptide Elongation Factor Tu / Q000235:genetics / Q000378:metabolism*; D011485:Protein Binding; D014176:Protein Biosynthesis; D011487:Protein Conformation; D012346:RNA, Transfer, Amino Acyl / Q000235:genetics / Q000378:metabolism*; D012270:Ribosomes / Q000378:metabolism
chemical_list: D029968:Escherichia coli Proteins; D012346:RNA, Transfer, Amino Acyl; D010444:Peptide Elongation Factor Tu