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An Internal Ribosome Entry Site Directs Translation of the 3′-Gene from Pelargonium Flower Break Virus Genomic RNA: Implications for Infectivity

Pelargonium flower break virus (PFBV, genus Carmovirus) has a single-stranded positive-sense genomic RNA (gRNA) which contains five ORFs. The two 5′-proximal ORFs encode the replicases, two internal ORFs encode movement proteins, and the 3′-proximal ORF encodes a polypeptide (p37) which plays a dual...

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Autores principales: Fernández-Miragall, Olga, Hernández, Carmen
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Public Library of Science 2011
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3144232/
https://www.ncbi.nlm.nih.gov/pubmed/21818349
http://dx.doi.org/10.1371/journal.pone.0022617
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author Fernández-Miragall, Olga
Hernández, Carmen
author_facet Fernández-Miragall, Olga
Hernández, Carmen
author_sort Fernández-Miragall, Olga
collection PubMed
description Pelargonium flower break virus (PFBV, genus Carmovirus) has a single-stranded positive-sense genomic RNA (gRNA) which contains five ORFs. The two 5′-proximal ORFs encode the replicases, two internal ORFs encode movement proteins, and the 3′-proximal ORF encodes a polypeptide (p37) which plays a dual role as capsid protein and as suppressor of RNA silencing. Like other members of family Tombusviridae, carmoviruses express ORFs that are not 5′-proximal from subgenomic RNAs. However, in one case, corresponding to Hisbiscus chlorotic ringspot virus, it has been reported that the 3′-proximal gene can be translated from the gRNA through an internal ribosome entry site (IRES). Here we show that PFBV also holds an IRES that mediates production of p37 from the gRNA, raising the question of whether this translation strategy may be conserved in the genus. The PFBV IRES was functional both in vitro and in vivo and either in the viral context or when inserted into synthetic bicistronic constructs. Through deletion and mutagenesis studies we have found that the IRES is contained within a 80 nt segment and have identified some structural traits that influence IRES function. Interestingly, mutations that diminish IRES activity strongly reduced the infectivity of the virus while the progress of the infection was favoured by mutations potentiating such activity. These results support the biological significance of the IRES-driven p37 translation and suggest that production of the silencing suppressor from the gRNA might allow the virus to early counteract the defence response of the host, thus facilitating pathogen multiplication and spread.
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spelling pubmed-31442322011-08-04 An Internal Ribosome Entry Site Directs Translation of the 3′-Gene from Pelargonium Flower Break Virus Genomic RNA: Implications for Infectivity Fernández-Miragall, Olga Hernández, Carmen PLoS One Research Article Pelargonium flower break virus (PFBV, genus Carmovirus) has a single-stranded positive-sense genomic RNA (gRNA) which contains five ORFs. The two 5′-proximal ORFs encode the replicases, two internal ORFs encode movement proteins, and the 3′-proximal ORF encodes a polypeptide (p37) which plays a dual role as capsid protein and as suppressor of RNA silencing. Like other members of family Tombusviridae, carmoviruses express ORFs that are not 5′-proximal from subgenomic RNAs. However, in one case, corresponding to Hisbiscus chlorotic ringspot virus, it has been reported that the 3′-proximal gene can be translated from the gRNA through an internal ribosome entry site (IRES). Here we show that PFBV also holds an IRES that mediates production of p37 from the gRNA, raising the question of whether this translation strategy may be conserved in the genus. The PFBV IRES was functional both in vitro and in vivo and either in the viral context or when inserted into synthetic bicistronic constructs. Through deletion and mutagenesis studies we have found that the IRES is contained within a 80 nt segment and have identified some structural traits that influence IRES function. Interestingly, mutations that diminish IRES activity strongly reduced the infectivity of the virus while the progress of the infection was favoured by mutations potentiating such activity. These results support the biological significance of the IRES-driven p37 translation and suggest that production of the silencing suppressor from the gRNA might allow the virus to early counteract the defence response of the host, thus facilitating pathogen multiplication and spread. Public Library of Science 2011-07-26 /pmc/articles/PMC3144232/ /pubmed/21818349 http://dx.doi.org/10.1371/journal.pone.0022617 Text en Fernández-Miragall, Hernández. http://creativecommons.org/licenses/by/4.0/ This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are properly credited.
spellingShingle Research Article
Fernández-Miragall, Olga
Hernández, Carmen
An Internal Ribosome Entry Site Directs Translation of the 3′-Gene from Pelargonium Flower Break Virus Genomic RNA: Implications for Infectivity
title An Internal Ribosome Entry Site Directs Translation of the 3′-Gene from Pelargonium Flower Break Virus Genomic RNA: Implications for Infectivity
title_full An Internal Ribosome Entry Site Directs Translation of the 3′-Gene from Pelargonium Flower Break Virus Genomic RNA: Implications for Infectivity
title_fullStr An Internal Ribosome Entry Site Directs Translation of the 3′-Gene from Pelargonium Flower Break Virus Genomic RNA: Implications for Infectivity
title_full_unstemmed An Internal Ribosome Entry Site Directs Translation of the 3′-Gene from Pelargonium Flower Break Virus Genomic RNA: Implications for Infectivity
title_short An Internal Ribosome Entry Site Directs Translation of the 3′-Gene from Pelargonium Flower Break Virus Genomic RNA: Implications for Infectivity
title_sort internal ribosome entry site directs translation of the 3′-gene from pelargonium flower break virus genomic rna: implications for infectivity
topic Research Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3144232/
https://www.ncbi.nlm.nih.gov/pubmed/21818349
http://dx.doi.org/10.1371/journal.pone.0022617
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