Global shape mimicry of tRNA within a viral internal ribosome entry site mediates translational reading frame selection.
Proc Natl Acad Sci U S A
; 112(47): E6446-55, 2015 Nov 24.
Article
em En
| MEDLINE
| ID: mdl-26554019
ABSTRACT
The dicistrovirus intergenic region internal ribosome entry site (IRES) adopts a triple-pseudoknotted RNA structure and occupies the core ribosomal E, P, and A sites to directly recruit the ribosome and initiate translation at a non-AUG codon. A subset of dicistrovirus IRESs directs translation in the 0 and +1 frames to produce the viral structural proteins and a +1 overlapping open reading frame called ORFx, respectively. Here we show that specific mutations of two unpaired adenosines located at the core of the three-helical junction of the honey bee dicistrovirus Israeli acute paralysis virus (IAPV) IRES PKI domain can uncouple 0 and +1 frame translation, suggesting that the structure adopts distinct conformations that contribute to 0 or +1 frame translation. Using a reconstituted translation system, we show that ribosomes assembled on mutant IRESs that direct exclusive 0 or +1 frame translation lack reading frame fidelity. Finally, a nuclear magnetic resonance/small-angle X-ray scattering hybrid approach reveals that the PKI domain of the IAPV IRES adopts an RNA structure that resembles a complete tRNA. The tRNA shape-mimicry enables the viral IRES to gain access to the ribosome tRNA-binding sites and form intermolecular contacts with the ribosome that are necessary for initiating IRES translation in a specific reading frame.
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Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Biossíntese de Proteínas
/
RNA de Transferência
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Fases de Leitura Aberta
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Dicistroviridae
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Sítios Internos de Entrada Ribossomal
Tipo de estudo:
Prognostic_studies
Limite:
Animals
/
Humans
Idioma:
En
Revista:
Proc Natl Acad Sci U S A
Ano de publicação:
2015
Tipo de documento:
Article