Taura syndrome virus IRES initiates translation by binding its tRNA-mRNA-like structural element in the ribosomal decoding center
RNA Therapeutics Institute; Department of Biochemistry and Molecular Pharmacology
Biochemistry, Biophysics, and Structural Biology | Cell and Developmental Biology | Genetics and Genomics | Therapeutics
In cap-dependent translation initiation, the open reading frame (ORF) of mRNA is established by the placement of the AUG start codon and initiator tRNA in the ribosomal peptidyl (P) site. Internal ribosome entry sites (IRESs) promote translation of mRNAs in a cap-independent manner. We report two structures of the ribosome-bound Taura syndrome virus (TSV) IRES belonging to the family of Dicistroviridae intergenic IRESs. Intersubunit rotational states differ in these structures, suggesting that ribosome dynamics play a role in IRES translocation. Pseudoknot I of the IRES occupies the ribosomal decoding center at the aminoacyl (A) site in a manner resembling that of the tRNA anticodon-mRNA codon. The structures reveal that the TSV IRES initiates translation by a previously unseen mechanism, which is conceptually distinct from initiator tRNA-dependent mechanisms. Specifically, the ORF of the IRES-driven mRNA is established by the placement of the preceding tRNA-mRNA-like structure in the A site, whereas the 40S P site remains unoccupied during this initial step.
DOI of Published Version
Proc Natl Acad Sci U S A. 2014 Jun 24;111(25):9139-44. doi: 10.1073/pnas.1406335111. Epub 2014 Jun 9. Link to article on publisher's site
Proceedings of the National Academy of Sciences of the United States of America
Koh, Cha San; Brilot, Axel F.; Grigorieff, Nikolaus; and Korostelev, Andrei A., "Taura syndrome virus IRES initiates translation by binding its tRNA-mRNA-like structural element in the ribosomal decoding center" (2014). RNA Therapeutics Institute Publications. 29.