The Cellular Decapping Activators LSm1, Pat1, and Dhh1 Control the Ratio of Subgenomic to Genomic Flock House Virus RNAs

Giménez‐Barcons, Mireia; Alves-Rodrigues, Isabel; Jungfleisch, Jennifer; Wynsberghe, Priscilla M. Van; Ahlquist, Paul; Díez, Juana

doi:10.1128/jvi.03327-12

Cited by 8 publications

(11 citation statements)

References 64 publications

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“…Confirmation of this hypothesis will have to await development of an experimental system that allows specific detection of RNA3, and we are currently in the process of designing suitable probes to that end. Interestingly, it was recently shown that the cellular decapping activators LSm1, Pat1, and Dhh1 are involved in FHV RNA replication in yeast and control the ratio of FHV RNA1 to subgenomic RNA3 (47). These decapping activators are known P-body components, and they may be poised for additional roles in the absence of a functional B2 protein.…”

Section: Discussionmentioning

confidence: 99%

Cytoplasmic Granule Formation and Translational Inhibition of Nodaviral RNAs in the Absence of the Double-Stranded RNA Binding Protein B2

Petrillo

Venter

Short

et al. 2013

J Virol

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bFlock House virus (FHV) is a positive-sense RNA insect virus with a bipartite genome. RNA1 encodes the RNA-dependent RNA polymerase, and RNA2 encodes the capsid protein. A third protein, B2, is translated from a subgenomic RNA3 derived from the 3= end of RNA1. B2 is a double-stranded RNA (dsRNA) binding protein that inhibits RNA silencing, a major antiviral defense pathway in insects. FHV is conveniently propagated in Drosophila melanogaster cells but can also be grown in mammalian cells. It was previously reported that B2 is dispensable for FHV RNA replication in BHK21 cells; therefore, we chose this cell line to generate a viral mutant that lacked the ability to produce B2. Consistent with published results, we found that RNA replication was indeed vigorous but the yield of progeny virus was negligible. Closer inspection revealed that infected cells contained very small amounts of coat protein despite an abundance of RNA2. B2 mutants that had reduced affinity for dsRNA produced analogous results, suggesting that the dsRNA binding capacity of B2 somehow played a role in coat protein synthesis. Using fluorescence in situ hybridization of FHV RNAs, we discovered that RNA2 is recruited into large cytoplasmic granules in the absence of B2, whereas the distribution of RNA1 remains largely unaffected. We conclude that B2, by binding to double-stranded regions in progeny RNA2, prevents recruitment of RNA2 into cellular structures, where it is translationally silenced. This represents a novel function of B2 that further contributes to successful completion of the nodaviral life cycle.T he nodaviruses are a family of positive-strand RNA viruses that naturally infect insects and fish. They have a bipartite genome that contains approximately 4,500 bases and encodes three proteins. The most thoroughly studied nodavirus is the insect virus Flock House virus (FHV), which has served as an important model system to investigate the structural and molecular basis of RNA replication, virus assembly, and inhibition of antiviral host responses (1). The larger of the two genomic RNAs, RNA1 (3.1 kb), encodes the RNAdependent RNA polymerase (RdRp; 112 kDa), which is located on the outer membrane of mitochondria in infected cells (2, 3). Viral RNA synthesis induces so-called spherules (4), i.e., membrane invaginations, which are thought to sequester the replication complexes and double-stranded RNA (dsRNA) intermediates to protect them from RNA silencing, a major antiviral pathway activated in insects upon infection with RNA viruses (5). Further protection from RNA silencing is afforded by FHV protein B2 (11.6 kDa), a dsRNA binding protein that is translated from RNA3 (387 nucleotides), a subgenomic RNA derived from the 3= end of RNA1 (6-8). The capsid protein, protein alpha (43 kDa), is translated from RNA2 (1.4 kb), the second genomic RNA segment.Although a seemingly simple virus, FHV uses a sophisticated regulatory system to control its gene expression. This regulation occurs at several levels and is currently incompletely understo...

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Section: Discussionmentioning

confidence: 99%

Cytoplasmic Granule Formation and Translational Inhibition of Nodaviral RNAs in the Absence of the Double-Stranded RNA Binding Protein B2

Petrillo

Venter

Short

et al. 2013

J Virol

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“…Our data show that the decapping activator Lsm1-7-Pat1 complex is exploited by BMV to sequentially regulate translation and replication of the viral genomes. Given the common replication strategies of (+)RNA viruses, the dependence on Lsm1-7-Pat1 complex for replication of at least four (+)RNA viruses infecting plants, insects, and humans and the dependence on Hfq, a homolog of Lsm1 in bacteria, for replication of the bacteriophage Qβ (Franze de Fernandez et al 1968;Diez et al 2000;Mas et al 2006;Scheller et al 2009;Chahar et al 2013;Gimenez-Barcons et al 2013), it is likely that these complexes are broadly used within this viral group by similar mechanisms as the ones described here. Moreover, the obtained results uncover functionalities of these versatile complexes that might provide novel insights into their essential role in cellular mRNA decay, since it also requires sequential binding and post-binding steps that are still not understood.…”

mentioning

confidence: 99%

“…Interestingly, in contrast to its decay function on cellular mRNAs, we and others have previously shown that the Lsm1-7-Pat1complex plays a fundamental role in the life cycle of a wide range of positive-strand RNA [(+)RNA] viruses including the plant Brome mosaic virus (BMV), the animal Flock House virus, the human Hepatitis C virus (HCV) and the emerging West Nile virus (WNV) (Diez et al 2000;Mas et al 2006;Scheller et al 2009;Chahar et al 2013;Gimenez-Barcons et al 2013). After these viruses enter the host cell, their single-stranded RNA genomes act as mRNAs and are directly translated to express the viral proteins.…”

Section: Introductionmentioning

confidence: 99%

The Lsm1-7-Pat1 complex promotes viral RNA translation and replication by differential mechanisms

Jungfleisch

Chowdhury

Alves-Rodrigues

et al. 2015

RNA

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The Lsm1-7-Pat1 complex binds to the 3 ′ end of cellular mRNAs and promotes 3 ′ end protection and 5 ′ -3 ′ decay. Interestingly, this complex also specifically binds to cis-acting regulatory sequences of viral positive-strand RNA genomes promoting their translation and subsequent recruitment from translation to replication. Yet, how the Lsm1-7-Pat1 complex regulates these two processes remains elusive. Here, we show that Lsm1-7-Pat1 complex acts differentially in these processes. By using a collection of well-characterized lsm1 mutant alleles and a system that allows the replication of Brome mosaic virus (BMV) in yeast we show that the Lsm1-7-Pat1 complex integrity is essential for both, translation and recruitment. However, the intrinsic RNA-binding ability of the complex is only required for translation. Consistent with an RNA-binding-independent function of the Lsm1-7-Pat1 complex on BMV RNA recruitment, we show that the BMV 1a protein, the sole viral protein required for recruitment, interacts with this complex in an RNA-independent manner. Together, these results support a model wherein Lsm1-7-Pat1 complex binds consecutively to BMV RNA regulatory sequences and the 1a protein to promote viral RNA translation and later recruitment out of the host translation machinery to the viral replication complexes.

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“…The simplicity of the FHV genome, combined with the advantages of yeast genetics make the FHV-yeast system another excellent model system to study basic aspects of (+)RNA biology, including virus–host interactions. Interestingly, three of the highly conserved host factors subverted by FHV are the decapping activators Lsm1–7, Pat1 and Dhh1 [48]. …”

Section: The Flock House Virus Subverts Features Of Decapping Protmentioning

confidence: 99%

“…This latter activity is essential for proper and timely expression of the different viral proteins throughout the different stages of the viral life cycle. Interestingly, depletion of Lsm1–7, Pat1 or Dhh1 disrupts this activity and alters the RNA1/RNA3 ratio [48]. …”

Section: The Flock House Virus Subverts Features Of Decapping Protmentioning

confidence: 99%

Use of Cellular Decapping Activators by Positive-Strand RNA Viruses

Jungfleisch

Blasco-Moreno

Díez

2016

Viruses

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Positive-strand RNA viruses have evolved multiple strategies to not only circumvent the hostile decay machinery but to trick it into being a priceless collaborator supporting viral RNA translation and replication. In this review, we describe the versatile interaction of positive-strand RNA viruses and the 5′-3′ mRNA decay machinery with a focus on the viral subversion of decapping activators. This highly conserved viral trickery is exemplified with the plant Brome mosaic virus, the animal Flock house virus and the human hepatitis C virus.

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The Cellular Decapping Activators LSm1, Pat1, and Dhh1 Control the Ratio of Subgenomic to Genomic Flock House Virus RNAs

Cited by 8 publications

References 64 publications

Cytoplasmic Granule Formation and Translational Inhibition of Nodaviral RNAs in the Absence of the Double-Stranded RNA Binding Protein B2

Cytoplasmic Granule Formation and Translational Inhibition of Nodaviral RNAs in the Absence of the Double-Stranded RNA Binding Protein B2

The Lsm1-7-Pat1 complex promotes viral RNA translation and replication by differential mechanisms

Use of Cellular Decapping Activators by Positive-Strand RNA Viruses

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