The use of internal ribosome entry sites (IRESs) is one of the unorthodox mechanisms exploited by viruses to initiate the translation of internal genes. Herein, we report a plant virus exploiting an IRES and its 3'-untranslated region (UTR) to express its internal genes, notably the 3'-proximal viral coat protein gene. Hibiscus chlorotic ringspot virus (HCRSV), a positive-strand non-polyadenyla...

In earlier studies, we identified short (6- to 22-nt) sequences that functioned as internal ribosome entry sites (IRESes) and enhanced translation. The size of these IRES elements suggested that they might be prevalent within the messenger population and that individual elements might affect the translation of different groups of mRNAs. To begin to assess the number of different IRES elements i...

The 5'-untranslated region of the ornithine decarboxylase (ODC) mRNA contains an internal ribosomal entry site (IRES). Mutational analysis of the ODC IRES has led to the identification of sequences necessary for cap-independent translation of the ODC mRNA. To discover novel IRES trans-acting factors (ITAFs), we performed a proteomics screen for proteins that regulate ODC translation using the w...

Rhopalosiphum padi virus (RhPV) is an insect virus of the Dicistroviridae family. Recently, the 579-nucleotide-long 5' untranslated region (UTR) of RhPV has been shown to contain an internal ribosome entry site (IRES) that functions efficiently in mammalian, plant, and insect in vitro translation systems. Here, the mechanism of action of the RhPV IRES has been characterized by reconstitution of...

The 5'-untranslated region of the hepatitis C virus (HCV) RNA contains a highly structured motif called IRES (Internal Ribosome Entry Site) responsible for the cap-independent initiation of the viral RNA translation. At first, the IRES binds to the 40S subunit without any initiation factors so that the initiation AUG codon falls into the P site. Here using an original site-directed cross-linkin...

The cricket paralysis virus internal ribosome entry site (IRES) can, in the absence of canonical initiation factors and initiator tRNA (Met-tRNAi), occupy the ribosomal P-site and assemble 80S ribosomes. Here we show that the IRES assembles mRNA-80S ribosome complexes by recruitment of 60S subunits to preformed IRES-40S complexes. Addition of eukaryotic elongation factors eEF1A and eEF2 and ami...

Intermittent rivers and ephemeral streams (IRES) are now recognized to support specific freshwater biodiversity ecosystem services represent approximately half of the global river network, a fraction that is likely increase in context changes. Despite large research efforts on IRES during past few decades, there need for developing systemic approach considers their hydrological, hydrogeological...

The HCV internal ribosome entry site (IRES) directly regulates the assembly of translation initiation complexes on viral mRNA by a sequential pathway that is distinct from canonical eukaryotic initiation. The HCV IRES can form a binary complex with an eIF-free 40S ribosomal subunit. Next, a 48S-like complex assembles at the AUG initiation codon upon association of eIF3 and ternary complex. 80S ...

The teschoviruses constitute a recently defined picornavirus genus. Most of the genome sequence of the porcine teschovirus-1 (PTV) Talfan and several other strains is known. We now demonstrate that initiation of protein synthesis occurs at nucleotide (nt) 412 on the PTV Talfan RNA and that nt 1 to 405 contains an internal ribosome entry site (IRES) that functions efficiently in vitro and within...

Hepatitis C virus (HCV), a widespread human pathogen, is dependent on a highly structured 5'-untranslated region of its mRNA, referred to as internal ribosome entry site (IRES), for the translation of all of its proteins. The HCV IRES initiates translation by directly binding to the small ribosomal subunit (40S), circumventing the need for many eukaryotic translation initiation factors required...