Skip to Content

Taura syndrome virus IRES initiates translation by binding its tRNA-mRNA-like structural element in the ribosomal decoding center

TitleTaura syndrome virus IRES initiates translation by binding its tRNA-mRNA-like structural element in the ribosomal decoding center
Publication TypeJournal Article
Year of Publication2014
AuthorsKoh, CS, Brilot AF, Grigorieff N, Korostelev AA
Refereed DesignationRefereed
JournalProc Natl Acad Sci U S A
Volume111
Pagination9139-9144
ISSN1091-6490
Abstract

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.

DOI10.1073/pnas.1406335111
PreviewAttachmentSize
Koh_PNAS2014.pdf3.54 MB