A sequence element that tunes Escherichia coli tRNA(Ala)(GGC) to ensure accurate decoding.

Sarah Ledoux, Mikołaj Olejniczak, Olke C Uhlenbeck

Nature structural & molecular biology 2009 Apr

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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.

Citation

Sarah Ledoux, Mikołaj Olejniczak, Olke C Uhlenbeck. A sequence element that tunes Escherichia coli tRNA(Ala)(GGC) to ensure accurate decoding. Nature structural & molecular biology. 2009 Apr;16(4):359-64