8hu1
E. coli 70S ribosome complexed with tRNA_Ile2 bearing L34 and ct6A37 in classical state
Structural highlights
FunctionRS3_ECOLI Binds the lower part of the 30S subunit head. Binds mRNA in the 70S ribosome, positioning it for translation (By similarity).[1] Plays a role in mRNA unwinding by the ribosome, possibly by forming part of a processivity clamp.[2] Publication Abstract from PubMedThe anticodon modifications of transfer RNAs (tRNAs) finetune the codon recognition on the ribosome for accurate translation. Bacteria and archaea utilize the modified cytidines, lysidine (L) and agmatidine (agm(2)C), respectively, in the anticodon of tRNA(Ile) to decipher AUA codon. L and agm(2)C contain long side chains with polar termini, but their functions remain elusive. Here we report the cryogenic electron microscopy structures of tRNAs(Ile) recognizing the AUA codon on the ribosome. Both modifications interact with the third adenine of the codon via a unique C-A geometry. The side chains extend toward 3' direction of the mRNA, and the polar termini form hydrogen bonds with 2'-OH of the residue 3'-adjacent to the AUA codon. Biochemical analyses demonstrated that AUA decoding is facilitated by the additional interaction between the polar termini of the modified cytidines and 2'-OH of the fourth mRNA residue. We also visualized cyclic N(6)-threonylcarbamoyladenosine (ct(6)A), another tRNA modification, and revealed a molecular basis how ct(6)A contributes to efficient decoding. Structural insights into the decoding capability of isoleucine tRNAs with lysidine and agmatidine.,Akiyama N, Ishiguro K, Yokoyama T, Miyauchi K, Nagao A, Shirouzu M, Suzuki T Nat Struct Mol Biol. 2024 May;31(5):817-825. doi: 10.1038/s41594-024-01238-1. , Epub 2024 Mar 27. PMID:38538915[3] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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