Taura syndrome virus IRES initiates translation by binding its tRNA-mRNA-like structural element in the ribosomal decoding center.
Proc Natl Acad Sci U S A
; 111(25): 9139-44, 2014 Jun 24.
Article
em En
| MEDLINE
| ID: mdl-24927574
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.
Palavras-chave
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Iniciação Traducional da Cadeia Peptídica
/
Picornaviridae
/
Ribossomos
/
RNA Mensageiro
/
RNA de Transferência
/
RNA Viral
/
Conformação de Ácido Nucleico
Idioma:
En
Ano de publicação:
2014
Tipo de documento:
Article