title: A sequence element that tunes Escherichia coli tRNA(Ala)(GGC) to ensure accurate decoding.
abstract: Mutating the rare A32-U38 nucleotide pair at the top of the anticodon loop of Escherichia coli tRNA(Ala)(GGC) to a more common U32-A38 pair results in a tRNA that performs almost normally on cognate codons but is unusually efficient in reading near-cognate codons. Pre-steady state kinetic measurements on E. coli ribosomes show that, unlike the wild-type tRNA(Ala)(GGC), the misreading mutant tRNA(Ala)(GGC) shows rapid GTP hydrolysis and no detectable proofreading on near-cognate codons. Similarly, tRNA(Ala)(GGC) mutated to contain C32-G38, a pair that is found in some bacterial tRNA(Ala)(GGC) sequences, was able to decode only the cognate codons, whereas tRNA(Ala)(GGC) containing a more common C32-A38 pair was able to decode all cognate and near-cognate codons tested. We propose that many of the phylogenetically conserved sequence elements present in each tRNA have evolved to suppress translation of near-cognate codons.
authors.affiliation: Department of Biochemistry, Molecular Biology and Cell Biology, Northwestern University, Evanston, Illinois 60208, USA.
authors.forename: Sarah
authors.initials: S
authors.lastname: Ledoux
authors.forename: Mikołaj
authors.initials: M
authors.lastname: Olejniczak
authors.forename: Olke C
authors.initials: OC
authors.lastname: Uhlenbeck
mesh_terms: D000409:Alanine / Q000235:genetics / Q000378:metabolism; D000926:Anticodon / Q000235:genetics*; D001483:Base Sequence; D003062:Codon / Q000235:genetics*; D017124:Conserved Sequence; D004926:Escherichia coli / Q000235:genetics / Q000502:physiology*; D006160:Guanosine Triphosphate / Q000378:metabolism; D007700:Kinetics; D008958:Models, Molecular; D017354:Point Mutation; D014176:Protein Biosynthesis; D012344:RNA, Transfer, Ala / Q000235:genetics* / Q000378:metabolism*
chemical_list: D000926:Anticodon; D003062:Codon; D012344:RNA, Transfer, Ala; D006160:Guanosine Triphosphate; D000409:Alanine