期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：2020
卷号：117
期号：28
页码：16333-16338
DOI：10.1073/pnas.2004170117
出版社：The National Academy of Sciences of the United States of America
摘要：Bacterial transfer RNAs (tRNAs) contain evolutionarily conserved sequences and modifications that ensure uniform binding to the ribosome and optimal translational accuracy despite differences in their aminoacyl attachments and anticodon nucleotide sequences. In the tRNA anticodon stem−loop, the anticodon sequence is correlated with a base pair in the anticodon loop (nucleotides 32 and 38) to tune the binding of each tRNA to the decoding center in the ribosome. Disruption of this correlation renders the ribosome unable to distinguish correct from incorrect tRNAs. The molecular basis for how these two tRNA features combine to ensure accurate decoding is unclear. Here, we solved structures of the bacterial ribosome containing either wild-type tRNA GGC Ala or tRNA GGC Ala containing a reversed 32–38 pair on cognate and near-cognate codons. Structures of wild-type tRNA GGC Ala bound to the ribosome reveal 23S ribosomal RNA (rRNA) nucleotide A1913 positional changes that are dependent on whether the codon−anticodon interaction is cognate or near cognate. Further, the 32–38 pair is destabilized in the context of a near-cognate codon−anticodon pair. Reversal of the pairing in tRNA GGC Ala ablates A1913 movement regardless of whether the interaction is cognate or near cognate. These results demonstrate that disrupting 32–38 and anticodon sequences alters interactions with the ribosome that directly contribute to misreading.
