The Regulation of Translation in Alphavirus-Infected Cells
Centro de Biología Molecular Severo Ochoa (CSIC-UAM), Universidad Autónoma de Madrid c/Nicolás Cabrera, 1., Cantoblanco, 28049 Madrid, Spain
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Viruses 2018, 10(2), 70; https://doi.org/10.3390/v10020070
Received: 15 January 2018 / Revised: 2 February 2018 / Accepted: 6 February 2018 / Published: 8 February 2018
(This article belongs to the Special Issue Advances in Alphavirus Research)
Sindbis virus (SINV) contains an RNA genome of positive polarity with two open reading frames (ORFs). The first ORF is translated from the genomic RNA (gRNA), rendering the viral non-structural proteins, whereas the second ORF is translated from a subgenomic mRNA (sgRNA), which directs the synthesis of viral structural proteins. SINV infection strongly inhibits host cell translation through a variety of different mechanisms, including the phosphorylation of the eukaryotic initiation factor eIF2α and the redistribution of cellular proteins from the nucleus to the cytoplasm. A number of motifs have been identified in SINV sgRNA, including a hairpin downstream of the AUG initiation codon, which is involved in the translatability of the viral sgRNA when eIF2 is inactivated. Moreover, a 3′-UTR motif containing three stem-loop structures is involved in the enhancement of translation in insect cells, but not in mammalian cells. Accordingly, SINV sgRNA has evolved several structures to efficiently compete for the cellular translational machinery. Mechanistically, sgRNA translation involves scanning of the 5′-UTR following a non-canonical mode and without the requirement for several initiation factors. Indeed, sgRNA-directed polypeptide synthesis occurs even after eIF4G cleavage or inactivation of eIF4A by selective inhibitors. Remarkably, eIF2α phosphorylation does not hamper sgRNA translation during the late phase of SINV infection. SINV sgRNA thus constitutes a unique model of a capped viral mRNA that is efficiently translated in the absence of several canonical initiation factors. The present review will mainly focus in the non-canonical mechanism of translation of SINV sgRNA.
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Keywords:
regulation of translation; alphaviruses; initiation factors; RNA structure; IRES
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MDPI and ACS Style
Carrasco, L.; Sanz, M.A.; González-Almela, E. The Regulation of Translation in Alphavirus-Infected Cells. Viruses 2018, 10, 70. https://doi.org/10.3390/v10020070
AMA Style
Carrasco L, Sanz MA, González-Almela E. The Regulation of Translation in Alphavirus-Infected Cells. Viruses. 2018; 10(2):70. https://doi.org/10.3390/v10020070
Chicago/Turabian StyleCarrasco, Luis; Sanz, Miguel A.; González-Almela, Esther. 2018. "The Regulation of Translation in Alphavirus-Infected Cells" Viruses 10, no. 2: 70. https://doi.org/10.3390/v10020070
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