The folding of the hepatitis C virus internal ribosome entry site depends on the 3'-end of the viral genome.
Hepatitis C virus (HCV) translation initiation is directed by an internal ribosome entry site (IRES) and regulated by distant regions at the 3'-end of the viral genome. Through a combination of improved RNA chemical probing methods, SHAPE structural analysis and screening of RNA accessibility using antisense oligonucleotide microarrays, here, we show that HCV IRES folding is fine-tuned by the genomic 3'-end. The essential IRES subdomains IIIb and IIId, and domain IV, adopted a different conformation in the presence of the cis-acting replication element and/or the 3'-untranslatable region compared to that taken up in their absence. Importantly, many of the observed changes involved significant decreases in the dimethyl sulfate or N-methyl-isatoic anhydride reactivity profiles at subdomains IIIb and IIId, while domain IV appeared as a more flexible element. These observations were additionally confirmed in a replication-competent RNA molecule. Significantly, protein factors are not required for these conformational differences to be made manifest. Our results suggest that a complex, direct and long-distance RNA-RNA interaction network plays an important role in the regulation of HCV translation and replication, as well as in the switching between different steps of the viral cycle.
Departamento de Biología Molecular, Instituto de Parasitología y Biomedicina López-Neyra, IPBLN-CSIC, Parque Tecnológico de Ciencias de la Salud, Avda. del Conocimiento s/n, Armilla, 18100 Granada, Spain. cristina_romero@ipb.csic.es
Cristina
C
Romero-López
Alicia
A
Barroso-Deljesus
Ana
A
García-Sacristán
Carlos
C
Briones
Alfredo
A
Berzal-Herranz
D020121:5' Untranslated Regions; D001483:Base Sequence; D016679:Genome, Viral; D016174:Hepacivirus / Q000235:genetics* / Q000502:physiology; D008969:Molecular Sequence Data; D009690:Nucleic Acid Conformation; D020411:Oligonucleotide Array Sequence Analysis; D059370:RNA Folding; D012367:RNA, Viral / Q000737:chemistry*; D014779:Virus Replication
D020121:5' Untranslated Regions; D012367:RNA, Viral