Tacaribe Virus Z Protein Interacts with the L Polymerase Protein To Inhibit Viral RNA Synthesis

Jácamo, Rodrigo; López, Nora; Wilda, Maximiliano; Franze-Fernández, Marı́a T.

doi:10.1128/jvi.77.19.10383-10393.2003

Cited by 74 publications

(98 citation statements)

References 29 publications

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“…1C). Previous results have revealed a similar phenotype using overexpressed Z in other arenaviral replicon systems (10,11,19), yet it has been impossible to determine whether Z directly impacts the viral RNA synthesis machinery or functions through alteration of an essential host cellular process. We therefore established an in vitro system to examine a potential direct effect of Z on viral RNA synthesis.…”

Section: Resultsmentioning

confidence: 77%

“…All of the enzymatic machinery required for viral RNA synthesis and mRNA transcription is contained within L, a 250-kDa multifunctional protein that is organized as a central ring-like RNA-dependent RNA-polymerase (RdRP) domain with three accessory appendages (9). As ectopic overexpression of Z induces potent inhibition of replicon-based reporter protein expression (10,11), Z has been hypothesized as an important regulator of L and arenaviral gene expression. However, Z is known to interact with several host factor binding partners, and it remains unclear whether Z directly regulates the viral RNA synthesis machinery or acts through alteration of an essential host process.…”

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confidence: 99%

See 1 more Smart Citation

Arenavirus Z protein controls viral RNA synthesis by locking a polymerase–promoter complex

Kranzusch

Whelan

2011

Proc. Natl. Acad. Sci. U.S.A.

104

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Arenaviruses form a noncytolytic infection in their rodent hosts, yet can elicit severe hemorrhagic disease in humans. How arenaviruses regulate gene expression remains unclear, and further understanding may provide insight into the dichotomy of these disparate infection processes. Here we reconstitute arenavirus RNA synthesis initiation and gene expression regulation in vitro using purified components and demonstrate a direct role of the viral Z protein in controlling RNA synthesis. Our data reveal that Z forms a species-specific complex with the viral polymerase (L) and inhibits RNA synthesis initiation by impairing L catalytic activity. This Z-L complex locks the viral polymerase in a promoter-bound, catalytically inactive state and may additionally ensure polymerase packaging during virion maturation. Z modulates host factors involved in cellular translation, proliferation, and antiviral signaling. Our data defines an additional role in governing viral RNA synthesis, revealing Z as the center of a network of host and viral connections that regulates viral gene expression.transcription factor | Machupo virus | matrix protein | negative-strand RNA virus | gene regulation T ranscription initiation is a fundamental focal point of gene expression regulation in all orders of life. Modulation of RNA synthesis affords an important response to stress, alterations in growth conditions, and environmental cues. Although initiation of RNA synthesis is often indirectly controlled through gene promoters and accessory signaling elements, regulation also occurs through factors directly interacting with and altering the catalytic potential of the RNA synthesis machinery itself (1). Studies with phage T7 and the T7 lysozyme repressor system have provided an important paradigm for control of viral RNA transcription (2, 3), but these processes remain a mystery for many eukaryotic viruses and medically relevant pathogens. Gene expression regulation is particularly critical for negative-sense RNA viruses of the family Arenaviridae, which must respond to input from the host environment to maintain a noncytolytic infection in their rodent reservoir (4). In stark contrast to this persistent infection, arenavirus infection in humans can lead to severe hemorrhagic fever disease and many arenaviruses represent important emerging pathogens (5). Intriguingly, recent evidence indicates that the balance between persistent and acute viral infection can be altered by a single mutation within the viral polymerase (6). Mechanistic insight into how arenaviruses tune gene expression and control viral RNA synthesis is required to further our understanding of the response of arenavirus infection to various host and cellular environments.Arenaviruses are the simplest of all hemorrhagic fever viruses, with only four viral proteins. The viral genome consists of two segments of single-stranded negative-sense RNA, where each segment encodes two proteins in an ambisense orientation. The small segment encodes for the viral glycoprotein, essential for entr...

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Section: Resultsmentioning

confidence: 77%

mentioning

confidence: 99%

Arenavirus Z protein controls viral RNA synthesis by locking a polymerase–promoter complex

Kranzusch

Whelan

2011

Proc. Natl. Acad. Sci. U.S.A.

104

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“…The sequences of the Z protein between P2 and P18 viruses are absolutely conserved, suggesting that no differences in its known multitudes of activity, such as virus assembly and budding [11,29,39,48] and regulation of viral RNA replication [9,10,18,24,31], are expected between the viruses. All changes on the L segments are localized to the L polymerase protein-coding region, five of which cause amino acid changes (N355D, A1808T, V1839L, D1889N, and D1906N) ( Table 2).…”

Section: Cloning and Sequence Analysis Of The L Segments Of The P2 Anmentioning

confidence: 99%

Genome comparison of virulent and avirulent strains of the Pichinde arenavirus

et al. 2008

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A virulent (P18) strain of the Pichinde arenavirus produces a disease in guinea pigs that somewhat mimics human Lassa fever, whereas an avirulent (P2) strain of this virus is attenuated in infected animals. It has been speculated that the composition of viral genomes may confer the degree of virulence in an infected host; the complete sequence of the viral genomes, however, is not known. Here, we provide for the first time genomic sequences of both S and L segments for both the P2 and P18 strains. Sequence comparisons identify three mutations in the GP1 subunit of the viral glycoprotein, one in the nucleoprotein NP, and five in the viral RNA polymerase L protein. These mutations, alone or in combination, may contribute to the acquired virulence of Pichinde infection in animals. The 3 amino acid changes in the variable region of the GP1 glycoprotein subunit may affect viral entry by altering its receptor-binding activity. While NP has previously been shown to modulate the host immune responses to viral infection, we found that the R374K change in this protein does not affect the NP function in suppressing interferon-β expression. Four out of the five amino acid changes in the L protein occur in a small region of the protein that may contribute to viral virulence by enhancing its function on viral genomic RNA synthesis.

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“…For Sindbis virus and Tobacco mosaic virus, with single genomic RNAs, the expression of the RNA-dependent RNA polymerase is decreased by readthrough of leaky termination codons (27,37,44,45). Translational control also plays an important role in regulating viral gene expression in negative-sense RNA viruses and retroviruses (19,28,31,41,49). Regulation of protein production from segmented plus-strand RNA viruses is less well understood.…”

mentioning

confidence: 99%

Selective Repression of Translation by the Brome Mosaic Virus 1a RNA Replication Protein

Gopinath

Kao

2007

J Virol

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Differential expression of viral replication proteins is essential for successful infection. We report here that overexpression of the brome mosaic virus (BMV) 1a protein can repress viral RNA replication in a dosagedependent manner. Using RNA replication-incompetent reporter constructs, repression of translation from BMV RNA1 and RNA2 was observed, suggesting that the effect on translation of the BMV RNA replication proteins is responsible for the decrease in RNA levels. Furthermore, repression of translation by 1a required the B box in the 5 -untranslated region (5 UTR); BMV RNA3 that lacks a B box in its 5 UTR is not subject to 1a-mediated translational inhibition. Mutations in either the methyltransferase or the helicase-like domains of 1a reduced the repression of replication and translation. These results suggest that in addition to its known functions in BMV RNA synthesis, 1a also regulates viral gene expression.Viruses must produce their gene products in the proper amounts and with the appropriate timing. Failure to do so can lead to innate defense responses from the host that may act on RNA replication intermediates (47). A number of mechanisms can contribute to the differential expression of viral products, such as ribosome shunting, leaky scanning, frameshifting, functional recoding, and reinitiation (11, 12). For Sindbis virus and Tobacco mosaic virus, with single genomic RNAs, the expression of the RNA-dependent RNA polymerase is decreased by readthrough of leaky termination codons (27,37,44,45). Translational control also plays an important role in regulating viral gene expression in negative-sense RNA viruses and retroviruses (19,28,31,41,49). Regulation of protein production from segmented plus-strand RNA viruses is less well understood.Brome mosaic virus (BMV), a member of the alphavirus-like superfamily of RNA viruses, is a model segmented positivestrand RNA virus. The BMV genome consists of three capped, messenger-sense genomic RNAs which have a tRNA-like structure within the 3Ј-untranslated region (3Ј UTR). Genomic RNA1 and RNA2 encode nonstructural proteins 1a and 2a, respectively, which direct RNA replication (33). Genomic RNA3 is a bicistronic RNA encoding the cell-to-cell movement protein (MP) and the coat protein (CP). The MP is translated from RNA3, whereas the 3Ј-proximal coat protein is translated from a subgenomic RNA4 that is made using minus-strand RNA3 as the template (33). In addition to replication in various plant species, BMV can replicate and transcribe its genome in Saccharomyces cerevisiae (20).The multifunctional 1a protein contains two domains separated by a proline-rich sequence. The N-terminal domain contains activities for 7-methyl-guanosine methyltransferase and covalent GTP binding required for viral RNA capping (2, 23). The C-terminal domain contains all of the motifs of the DEAD box RNA helicase domain, with ATPase and GTPase activities (24, 48). 1a is the primary viral protein determinant for the subcellular localization of the BMV RNA replication complex (9, 39, ...

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Tacaribe Virus Z Protein Interacts with the L Polymerase Protein To Inhibit Viral RNA Synthesis

Cited by 74 publications

References 29 publications

Arenavirus Z protein controls viral RNA synthesis by locking a polymerase–promoter complex

Arenavirus Z protein controls viral RNA synthesis by locking a polymerase–promoter complex

Genome comparison of virulent and avirulent strains of the Pichinde arenavirus

Selective Repression of Translation by the Brome Mosaic Virus 1a RNA Replication Protein

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