Dataset Information

Structural and Functional Diversity of Plant Virus 3'-Cap-Independent Translation Enhancers (3'-CITEs).

ABSTRACT: Most of the positive-strand RNA plant viruses lack the 5'-cap and/or the poly(A)-tail that act synergistically to stimulate canonical translation of cellular mRNAs. However, they have RNA elements in the 5'- or 3'-untranslated regions of their RNAs that are required for their cap-independent translation. Cap-independent translation enhancers (CITEs) have been identified in the genomic 3'-end of viruses belonging to the family Tombusviridae and the genus Luteovirus. Seven classes of 3'-CITEs have been described to date based on their different RNA structures. They generally control the efficient formation of the translation initiation complex by varying mechanisms. Some 3'-CITEs bind eukaryotic translation initiation factors, others ribosomal subunits, bridging these to the 5'-end by different mechanisms, often long-distance RNA-RNA interactions. As previously proposed and recently found in one case in nature, 3'-CITEs are functionally independent elements that are transferable through recombination between viral genomes, leading to potential advantages for virus multiplication. In this review, the knowledge on 3'-CITEs and their functioning is updated. We also suggest that there is local structural conservation in the regions interacting with eIF4E of 3'-CITEs belonging to different classes.

SUBMITTER: Truniger V

PROVIDER: S-EPMC5712577 | biostudies-literature | 2017

REPOSITORIES: biostudies-literature

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Structural and Functional Diversity of Plant Virus 3'-Cap-Independent Translation Enhancers (3'-CITEs).

Truniger Verónica V Miras Manuel M Aranda Miguel A MA

Frontiers in plant science 20171129

Most of the positive-strand RNA plant viruses lack the 5'-cap and/or the poly(A)-tail that act synergistically to stimulate canonical translation of cellular mRNAs. However, they have RNA elements in the 5'- or 3'-untranslated regions of their RNAs that are required for their cap-independent translation. Cap-independent translation enhancers (CITEs) have been identified in the genomic 3'-end of viruses belonging to the family <i>Tombusviridae</i> and the genus <i>Luteovirus</i>. Seven classes of ...[more]

PMID: 29238357

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Project description:Many plant viruses without 5' caps or 3' poly(A) tails contain 3' proximal, cap-independent translation enhancers (3'CITEs) that bind to ribosomal subunits or translation factors thought to assist in ribosome recruitment. Most 3'CITEs participate in a long-distance kissing-loop interaction with a 5' proximal hairpin to deliver ribosomal subunits to the 5' end for translation initiation. Pea Enation Mosaic Virus (PEMV) contains two adjacent 3'CITEs in the center of its 703-nucleotide 3' untranslated region (3'UTR), the ribosome-binding, kissing-loop T-shaped structure (kl-TSS) and eukaryotic translation initiation factor 4E-binding Panicum mosaic virus-like translation enhance (PTE). We now report that PEMV contains a third, independent 3'CITE located near the 3' terminus. This 3'CITE is composed of three hairpins and two pseudoknots, similar to the TSS 3'CITE of the carmovirus Turnip crinkle virus (TCV). As with the TCV TSS, the PEMV 3'TSS is predicted to fold into a T-shaped structure that binds to 80S ribosomes and 60S ribosomal subunits. A small hairpin (kl-H) upstream of the 3'TSS contains an apical loop capable of forming a kissing-loop interaction with a 5' proximal hairpin and is critical for the accumulation of full-length PEMV in protoplasts. Although the kl-H and 3'TSS are dispensable for the translation of a reporter construct containing the complete PEMV 3'UTR in vitro, deleting the normally required kl-TSS and PTE 3'CITEs and placing the kl-H and 3'TSS proximal to the reporter termination codon restores translation to near wild-type levels. This suggests that PEMV requires three 3'CITEs for proper translation and that additional translation enhancers may have been missed if reporter constructs were used in 3'CITE identification. Importance: The rapid life cycle of viruses requires efficient translation of viral-encoded proteins. Many plant RNA viruses contain 3' cap-independent translation enhancers (3'CITEs) to effectively compete with ongoing host translation. Since only single 3'CITEs have been identified for the vast majority of individual viruses, it is widely accepted that this is sufficient for a virus's translational needs. Pea Enation Mosaic Virus possesses a ribosome-binding 3'CITE that can connect to the 5' end through an RNA-RNA interaction and an adjacent eukaryotic translation initiation factor 4E-binding 3'CITE. We report the identification of a third 3'CITE that binds weakly to ribosomes and requires an upstream hairpin to form a bridge between the 3' and 5' ends. Although both ribosome-binding 3'CITEs are critical for virus accumulation in vivo, only the CITE closest to the termination codon of a reporter open reading frame is active, suggesting that artificial constructs used for 3'CITE identification may underestimate the number of CITEs that participate in translation.

Dataset Information

Structural and Functional Diversity of Plant Virus 3'-Cap-Independent Translation Enhancers (3'-CITEs).

Publications

Structural and Functional Diversity of Plant Virus 3'-Cap-Independent Translation Enhancers (3'-CITEs).

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