The Experts below are selected from a list of 39438 Experts worldwide ranked by ideXlab platform
Sean P J Whelan - One of the best experts on this subject based on the ideXlab platform.
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vesicular stomatitis Virus transcription is inhibited by trim69 in the interferon induced antiviral state
Journal of Virology, 2019Co-Authors: Tonya Kueck, Sean P J Whelan, Louismarie Bloyet, Elena Cassella, Trinity Zang, Fabian Schmidt, Vesna Brusic, Gergely Tekes, Owen Pornillos, Paul D BieniaszAbstract:Interferons (IFNs) induce the expression of interferon-stimulated genes (ISGs), many of which are responsible for the cellular antiviral state in which the replication of numerous Viruses is blocked. How the majority of individual ISGs inhibit the replication of particular Viruses is unknown. We conducted a loss-of-function screen to identify genes required for the activity of alpha interferon (IFN-α) against vesicular stomatitis Virus, Indiana serotype (VSVIND), a prototype Negative-Strand RNA Virus. Our screen revealed that TRIM69, a member of the tripartite motif (TRIM) family of proteins, is a VSVIND inhibitor. TRIM69 potently inhibited VSVIND replication through a previously undescribed transcriptional inhibition mechanism. Specifically, TRIM69 physically associates with the VSVIND phosphoprotein (P), requiring a specific peptide target sequence encoded therein. P is a cofactor for the viral polymerase and is required for viral RNA synthesis, as well as the assembly of replication compartments. By targeting P, TRIM69 inhibits pioneer transcription of the incoming virion-associated minus-strand RNA, thereby preventing the synthesis of viral mRNAs, and consequently impedes all downstream events in the VSVIND replication cycle. Unlike some TRIM proteins, TRIM69 does not inhibit viral replication by inducing degradation of target viral proteins. Rather, higher-order TRIM69 multimerization is required for its antiviral activity, suggesting that TRIM69 functions by sequestration or anatomical disruption of the viral machinery required for VSVIND RNA synthesis. IMPORTANCE Interferons are important antiviral cytokines that work by inducing hundreds of host genes whose products inhibit the replication of many Viruses. While the antiviral activity of interferon has long been known, the identities and mechanisms of action of most interferon-induced antiviral proteins remain to be discovered. We identified gene products that are important for the antiviral activity of interferon against vesicular stomatitis Virus (VSV), a model Virus that whose genome consists of a single RNA molecule with negative-sense polarity. We found that a particular antiviral protein, TRIM69, functions by a previously undescribed molecular mechanism. Specifically, TRIM69 interacts with and inhibits the function of a particular phosphoprotein (P) component of the viral transcription machinery, preventing the synthesis of viral messenger RNAs.
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vesicular stomatitis Virus transcription is inhibited by trim69 in the interferon induced antiviral state
bioRxiv, 2019Co-Authors: Tonya Kueck, Louismarie Bloyet, Elena Cassella, Trinity Zang, Fabian Schmidt, Vesna Brusic, Gergely Tekes, Owen Pornillos, Sean P J WhelanAbstract:ABSTRACT Interferons (IFNs) induce the expression of many interferon stimulated genes (ISGs), many of which are responsible for the cellular ‘antiviral state’ in which the replication of numerous Viruses is blocked. How the majority of individual ISGs inhibit the replication of particular Viruses is unknown. We conducted a loss-of-function screen to identify genes required for the activity of IFNα against vesicular stomatitis Virus, Indiana serotype (VSVIND), a prototype negative strand RNA Virus. Our screen revealed that TRIM69, a member of tripartite motif family of proteins, is a VSVIND inhibitor. TRIM69 potently inhibited VSVIND replication through a previously undescribed transcriptional inhibition mechanism. Specifically, TRIM69 physically associates with the VSVIND phosphoprotein (P), requiring a specific peptide target sequence encoded therein. P is a cofactor for the viral polymerase, and is required for viral RNA synthesis as well as the assembly of replication compartments. By targeting P, TRIM69 inhibits pioneer transcription of the incoming virion-associated minus strand RNA, thereby preventing the synthesis of viral mRNAs, and consequently impedes all downstream events in the VSVIND replication cycle. Unlike some TRIM proteins, TRIM69 does not inhibit viral replication by inducing degradation of target viral proteins. Rather, higher-order TRIM69 multimerization is required for its antiviral activity, suggesting that TRIM69 functions by sequestration or anatomical disruption of the viral machinery required for VSVIND RNA synthesis. SIGNIFICANCE STATEMENT Interferons are important antiviral cytokines that work by inducing hundreds of host genes whose products inhibit replication of many Viruses. While the antiviral activity of interferon has long been known, the identities and mechanisms of action of most interferon-induced antiviral proteins remain to be discovered. We identified gene products that are important for the antiviral activity of interferon against vesicular stomatitis Virus (VSV) a model Virus that whose genome consists a single RNA molecule with negative sense polarity. We found that a particular antiviral protein, TRIM69, functions by a previously undescribed molecular mechanism. Specifically, TRIM69 interacts with, and inhibits the function, of a particular phosphoprotein (P) component the viral transcription machinery, preventing the synthesis of viral messenger RNAs.
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assembly of a functional machupo Virus polymerase complex
Proceedings of the National Academy of Sciences of the United States of America, 2010Co-Authors: Philip J Kranzusch, Andreas D Schenk, Amal A Rahmeh, Sheli R Radoshitzky, Sina Bavari, Thomas Walz, Sean P J WhelanAbstract:Segmented negative-sense Viruses of the family Arenaviridae encode a large polymerase (L) protein that contains all of the enzymatic activities required for RNA synthesis. These activities include an RNA-dependent RNA polymerase (RdRP) and an RNA endonuclease that cleaves capped primers from cellular mRNAs to prime transcription. Using purified catalytically active Machupo Virus L, we provide a view of the overall architecture of this multifunctional polymerase and reconstitute complex formation with an RNA template in vitro. The L protein contains a central ring domain that is similar in appearance to the RdRP of dsRNA Viruses and multiple accessory appendages that may be responsible for 5′ cap formation. RNA template recognition by L requires a sequence-specific motif located at positions 2–5 in the 3′ terminus of the viral genome. Moreover, L-RNA complex formation depends on single-stranded RNA, indicating that inter-termini dsRNA interactions must be partially broken for complex assembly to occur. Our results provide a model for arenaVirus polymerase–template interactions and reveal the structural organization of a Negative-Strand RNA Virus L protein.
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efficient recovery of infectious vesicular stomatitis Virus entirely from cdna clones
Proceedings of the National Academy of Sciences of the United States of America, 1995Co-Authors: Sean P J Whelan, John N. Barr, Laurence A Ball, Gail W. WertzAbstract:Infectious vesicular stomatitis Virus (VSV), the prototypic nonsegmented Negative-Strand RNA Virus, was recovered from a full-length cDNA clone of the viral genome. Bacteriophage T7 RNA polymerase expressed from a recombinant vaccinia Virus was used to drive the synthesis of a genome-length positive-sense transcript of VSV from a cDNA clone in baby hamster kidney cells that were simultaneously expressing the VSV nucleocapsid protein, phosphoprotein, and polymerase from separate plasmids. Up to 10(5) infectious Virus particles were obtained from transfection of 10(6) cells, as determined by plaque assays. This Virus was amplified on passage, neutralized by VSV-specific antiserum, and shown to possess specific nucleotide sequence markers characteristic of the cDNA. This achievement renders the biology of VSV fully accessible to genetic manipulation of the viral genome. In contrast to the success with positive-sense RNA, attempts to recover infectious Virus from negative-sense T7 transcripts were uniformly unsuccessful, because T7 RNA polymerase terminated transcription at or near the VSV intergenic junctions.
Stephen Cusack - One of the best experts on this subject based on the ideXlab platform.
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structural insights into RNA synthesis by the influenza Virus transcription replication machine
Virus Research, 2017Co-Authors: Alexander Pflug, M Lukarska, Patricia Resainfante, Stefan Reich, Stephen CusackAbstract:Abstract Influenza Virus is a segmented, negative strand RNA Virus with each genome segment being packaged in a distinct ribonucleoprotein particle (RNP). The RNP consists of the heterotrimeric viral RNA-dependent RNA polymerase bound to the conserved 5′ and 3′ ends of the genome segment (the viral promoter) with the rest of the viral RNA (vRNA) being covered by multiple copies of nucleoprotein. This review focusses on the new insights that recent crystal structures have given into the detailed molecular mechanisms by which the polymerase performs both transcription and replication of the vRNA genome. Promoter binding, in particular that of 5′ end, is essential to allosterically activate all polymerase functions. Transcription is initiated by the hijacking of nascent, capped host transcripts by the process of ‘cap-snatching’, for which the viral polymerase makes an essential interaction with the C-terminal domain (CTD) of cellular RNA polymerase II. The structures allow a coherent mechanistic model of the subsequent cap-snatching, cap-dependent priming, elongation and self-polyadenylation steps of viral mRNA synthesis. During replication, the vRNA is copied without modification into complementary RNA (cRNA) which is packaged into cRNPs. A priming loop located in the polymerase active site is required for the unprimed synthesis of cRNA from vRNA, but is not required for cRNA to vRNA replication due to differences in the mode of initiation of RNA synthesis. Overall a picture emerges of influenza polymerase being a highly complex, flexible and dynamic machine. The challenge remains to understand in more detail how it functions within the RNP and how interacting host factors modulate its activity in the cellular context. Finally, these detailed insights have opened up new opportunities for structure-based antiviral drug design targeting multiple aspects of polymerase function.
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Structural Insights into BunyaVirus Replication and Its Regulation by the vRNA Promoter
Cell, 2015Co-Authors: Piotr Gerlach, Stephen Cusack, Hélène Malet, Juan RegueraAbstract:Segmented Negative-Strand RNA Virus (sNSV) polymerases transcribe and replicate the viral RNA (vRNA) within a ribonucleoprotein particle (RNP). We present cryo-EM and X-ray structures of, respectively, apo- and vRNA bound La Crosse orthobunyaVirus (LACV) polymerase that give atomic-resolution insight into how such RNPs perform RNA synthesis. The complementary 3' and 5' vRNA extremities are sequence specifically bound in separate sites on the polymerase. The 5' end binds as a stem-loop, allosterically structuring functionally important polymerase active site loops. Identification of distinct template and product exit tunnels allows proposal of a detailed model for template-directed replication with minimal disruption to the circularised RNP. The similar overall architecture and vRNA binding of monomeric LACV to heterotrimeric influenza polymerase, despite high sequence divergence, suggests that all sNSV polymerases have a common evolutionary origin and mechanism of RNA synthesis. These results will aid development of replication inhibitors of diverse, serious human pathogenic Viruses.
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segmented negative strand RNA Virus nucleoprotein structure
Current Opinion in Virology, 2014Co-Authors: Juan Reguera, Stephen Cusack, Daniel KolakofskyAbstract:Negative strand RNA Virus (NSV) genomes are never free, but always found assembled with multiple copies of their nucleoprotein, as RNPs. A flurry of papers describing the X-ray crystal structures of several segmented NSV nucleoproteins have recently appeared. The most significant feature of these various structures is that the arms that are used to oligomerize the nucleoproteins on their genome RNAs are highly flexible, permitting these RNPs to assume virtually unlimited geometries. The structural flexibility of segmented NSV RNPs is undoubtedly important in all aspects of their biology, including genome replication and circularization, and the selection of one copy of each segment for packaging into Virus particles.
Paul D Bieniasz - One of the best experts on this subject based on the ideXlab platform.
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vesicular stomatitis Virus transcription is inhibited by trim69 in the interferon induced antiviral state
Journal of Virology, 2019Co-Authors: Tonya Kueck, Sean P J Whelan, Louismarie Bloyet, Elena Cassella, Trinity Zang, Fabian Schmidt, Vesna Brusic, Gergely Tekes, Owen Pornillos, Paul D BieniaszAbstract:Interferons (IFNs) induce the expression of interferon-stimulated genes (ISGs), many of which are responsible for the cellular antiviral state in which the replication of numerous Viruses is blocked. How the majority of individual ISGs inhibit the replication of particular Viruses is unknown. We conducted a loss-of-function screen to identify genes required for the activity of alpha interferon (IFN-α) against vesicular stomatitis Virus, Indiana serotype (VSVIND), a prototype Negative-Strand RNA Virus. Our screen revealed that TRIM69, a member of the tripartite motif (TRIM) family of proteins, is a VSVIND inhibitor. TRIM69 potently inhibited VSVIND replication through a previously undescribed transcriptional inhibition mechanism. Specifically, TRIM69 physically associates with the VSVIND phosphoprotein (P), requiring a specific peptide target sequence encoded therein. P is a cofactor for the viral polymerase and is required for viral RNA synthesis, as well as the assembly of replication compartments. By targeting P, TRIM69 inhibits pioneer transcription of the incoming virion-associated minus-strand RNA, thereby preventing the synthesis of viral mRNAs, and consequently impedes all downstream events in the VSVIND replication cycle. Unlike some TRIM proteins, TRIM69 does not inhibit viral replication by inducing degradation of target viral proteins. Rather, higher-order TRIM69 multimerization is required for its antiviral activity, suggesting that TRIM69 functions by sequestration or anatomical disruption of the viral machinery required for VSVIND RNA synthesis. IMPORTANCE Interferons are important antiviral cytokines that work by inducing hundreds of host genes whose products inhibit the replication of many Viruses. While the antiviral activity of interferon has long been known, the identities and mechanisms of action of most interferon-induced antiviral proteins remain to be discovered. We identified gene products that are important for the antiviral activity of interferon against vesicular stomatitis Virus (VSV), a model Virus that whose genome consists of a single RNA molecule with negative-sense polarity. We found that a particular antiviral protein, TRIM69, functions by a previously undescribed molecular mechanism. Specifically, TRIM69 interacts with and inhibits the function of a particular phosphoprotein (P) component of the viral transcription machinery, preventing the synthesis of viral messenger RNAs.
Peter L. Collins - One of the best experts on this subject based on the ideXlab platform.
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respiratory syncytial Virus virology reverse genetics and pathogenesis of disease
Current Topics in Microbiology and Immunology, 2013Co-Authors: Peter L. Collins, Rachel Fearns, Barney S GrahamAbstract:Human respiratory syncytial Virus (RSV) is an enveloped, nonsegmented Negative-Strand RNA Virus of family Paramyxoviridae. RSV is the most complex member of the family in terms of the number of genes and proteins. It is also relatively divergent and distinct from the prototype members of the family. In the past 30 years, we have seen a tremendous increase in our understanding of the molecular biology of RSV based on a succession of advances involving molecular cloning, reverse genetics, and detailed studies of protein function and structure. Much remains to be learned. RSV disease is complex and variable, and the host and viral factors that determine tropism and disease are poorly understood. RSV is notable for a historic vaccine failure in the 1960s involving a formalin-inactivated vaccine that primed for enhanced disease in RSV naive recipients. Live vaccine candidates have been shown to be free of this complication. However, development of subunit or other protein-based vaccines for pediatric use is hampered by the possibility of enhanced disease and the difficulty of reliably demonstrating its absence in preclinical studies.
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what are the risks hypothetical and observed of recombination involving live vaccines and vaccine vectors based on nonsegmented negative strain RNA Viruses
Journal of Virology, 2008Co-Authors: Peter L. Collins, Alexander Bukreyev, Brian R MurphyAbstract:Newcastle disease Virus (NDV) is a nonsegmented Negative-Strand RNA Virus (NNSV) that is being developed as a potential vaccine vector for use in poultry (7, 12, 17) and humans (5, 6). The primary proposed human use would be to express protective antigens of highly pathogenic agents for outbreak control. We noted (1) that one of the advantages of NDV is that “gene exchange seems to be rare for nonsegmented negative strand RNA Viruses, with few reported instances. This differs to the frequent gene reassortment observed for segmented Viruses, such as influenza Virus and rotaVirus, and the high frequency of recombination observed for certain Viruses, such as coronaVirus and polioVirus.” In a recent letter to the editor (9), Han et al. criticized our studies, suggesting that we (i) dismissed the possibility of recombination, (ii) failed to recognize the potentially adverse consequences of recombination, and (iii) did not experimentally address the potential for the instability of the inserted foreign gene. There indeed is evidence consistent with NNSV recombination yielding mosaic Virus, but it seems to be much less frequent than for the recombinogenic Viruses noted above (4). There have been many attempts to demonstrate genetic exchange between NNSVs in vitro, with only a single reported clear example of a resulting mosaic Virus (13, 16). There also is indirect evidence consistent with NNSV recombination in nature, based on the occasional discovery of a Virus with sequence discontinuity suggestive of a recombination breakpoint (4, 10, 11, 14, 15, 18, 20). This discovery has involved closely related Viruses, has not been reported to involve NNSVs with substantial sequence differences, and seems to be an infrequent event compared to its occurrence in the other Viruses noted above. History provides an extensive safety record supporting the view that NNSV genetic exchange is not an important practical concern for vaccinology. A variety of live, attenuated NNSV vaccines are in veterinary, agriculture, and human use, such as NDV in poultry and mumps and measles Viruses in humans. Indeed, the mumps and measles vaccines often are administered in combination, as are certain veterinary NNSV vaccines. We agree that recombination may sometimes occur between a vaccine Virus and its circulating wild-type counterpart. There is suggestive evidence that this has occurred between the NDV vaccine Virus and a circulating NDV strain (8), although we know of no similar evidence for mumps or measles Virus. Recombination yields a Virus with a mosaic genome containing sections from the parents. This Virus likely would exhibit a virulence phenotype resembling one parent or the other or something in between. It thus does not create a hazard exceeding that of the circulating wild-type Virus already present. This is supported by the history of vaccine use: despite long-standing worldwide use of a number of live NNSV vaccines, there have been no reported adverse events attributable to genetic exchange involving an NNSV vaccine. There have been no reports of untoward vaccine-related NNSVs emerging with novel clinical or environmental footprints. Whatever low risk is posed by NNSV genetic exchange, that risk already exists in nature and was not created by the use of live vaccines. Indeed, the restricted infectivity and restricted replication characteristic of an attenuated vaccine strain limit its opportunity to participate in the dual infections necessary for genetic exchange. In addition, the herd immunity induced by an effective vaccine reduces the circulating Virus, thereby reducing the opportunity for recombination (15). We believe that these considerations indicate that genetic exchange does not pose a realistic safety concern for the use of live NNSV-based vaccines. Regarding the specific use of NDV as a vaccine vector in humans, the possibility of recombination is even more remote, and its implications are no more dire. Natural infection of humans with NDV is not common, and NDV is highly restricted for replication in primates (1, 2). This reduced infectivity and reduced replication greatly reduces the opportunity for genetic exchange. Furthermore, even if a recombinant Virus is generated, it would remain highly restricted for replication and spread, since both parents, in this case, the NDV vector and a naturally circulating NDV strain, are restricted to humans. Any recombinant Virus would also be subject to neutralization by the burgeoning host immune response. In addition, NDV has only a low level of sequence relatedness with potential circulating human NNSVs; as already noted, recombination between dissimilar NNSVs has not been reported and presumably is rare indeed. We note that expressed foreign proteins in NNSVs do not appear to enhance the virulence of the vector or shift its tropism but rather seem to be moderately attenuating (3, 19). Obviously, one must confirm this for each vector/insert combination, using both avian and mammalian experimental species. However, if the foreign inserted gene is indeed silent with regard to virulence, its effect in any recombinants would be neutral or attenuating. Finally, regarding concern about the potential instability of the inserted foreign gene, a number of studies have indicated that inserts borne by NNSVs are surprisingly stable (3). The inserts have been shown to gradually accumulate point mutations that may inactivate the expression of the protein but do not introduce safety concerns. In any event, sequence integrity would be monitored during vaccine production and use in humans. Situations can be envisioned where potential genetic exchange between certain live vaccines and circulating Viruses might be of concern. For example, the use of a live influenza Virus vaccine bearing one or more gene segments from a highly pathogenic strain of avian influenza Virus has the potential to introduce these genes into other circulating human Viruses by reassortment. The use of an attenuated version of the severe acute respiratory syndrome coronaVirus as a vaccine might result in recombination with circulating animal or human coronaViruses to create novel mosaic Viruses. In contrast, with an NDV vector, the foreign gene is locked in the NDV nucleocapsid and is replicated and expressed by the NDV polymerase. Thus, an inserted avian influenza Virus or coronaVirus gene in an NDV vector is not situated to participate in influenza Virus-mediated reassortment or coronaVirus-mediated recombination. This is an important safety advantage. Vaccines represent one of the great successes of science, have saved countless lives, and have removed one terrible pathogen from circulation and brought others under control. Paradoxically, there is considerable public resistance to vaccines despite their successes and despite the possibility of wider outbreaks of human infections with avian influenza Virus and other emerging Viruses as well as the potential for bioterrorism. It is imperative to not make the situation worse with vague and unsubstantiated calls of alarm. Genetic instability and genetic exchange are inescapable attributes of Viruses, but as argued above, they did not begin with live vaccines and do not necessarily compromise vaccine safety. At this time, there is no realistic basis for suggesting that recombination by NDV is a significant safety problem either for its present use as a live vaccine or for its potential use as a vaccine vector.
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Transcription elongation factor of respiratory syncytial Virus, a nonsegmented Negative-Strand RNA Virus.
Proceedings of the National Academy of Sciences, 1996Co-Authors: Peter L. Collins, Myron G. Hill, Juan Cristina, Haim GrosfeldAbstract:RNA synthesis by the paramyxoVirus respiratory syncytial Virus, a ubiquitous human pathogen, was found to be more complex than previously appreciated for the nonsegmented Negative-Strand RNA Viruses. Intracellular RNA replication of a plasmid-encoded "minigenome" analog of viral genomic RNA was directed by coexpression of the N, P, and L proteins. But, under these conditions, the greater part of mRNA synthesis terminated prematurely. This difference in processivity between the replicase and the transcriptase was unanticipated because the two enzymes ostensively shared the same protein subunits and template. Coexpression of the M2 gene at a low level of input plasmid resulted in the efficient production of full-length mRNA and, in the case of a dicistronic minigenome, sequential transcription. At a higher level, coexpression of the M2 gene inhibited transcription and RNA replication. The M2 mRNA contains two overlapping translational open reading frames (ORFs), which were segregated for further analysis. Expression of the upstream ORF1, which encoded the previously described 22-kDa M2 protein, was associated with transcription elongation. A model involving this protein in the balance between transcription and replication is proposed. ORF2, which lacks an assigned protein, was associated with inhibition of RNA synthesis. We propose that this activity renders nucleocapsids synthetically quiescent prior to incorporation into virions.
Juan Reguera - One of the best experts on this subject based on the ideXlab platform.
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Structure and function of the Toscana Virus cap-snatching endonuclease
Nucleic Acids Research, 2019Co-Authors: Rhian Jones, Sana Lessoued, Kristina Meier, Stéphanie Devignot, Sergio Barata-garcía, Maria Mate, Gabriel Bragagnolo, Friedemann Weber, Maria Rosenthal, Juan RegueraAbstract:Toscana Virus (TOSV) is an arthropod-borne human pathogen responsible for seasonal outbreaks of fever and meningoencephalitis in the Mediterranean basin. TOSV is a segmented Negative-Strand RNA Virus (sNSV) that belongs to the genus phleboVirus (family Phenuiviridae, order Bunyavirales), encompassing other important human pathogens such as Rift Valley fever Virus (RVFV). Here, we carried out a structural and functional characterization of the TOSV cap-snatching endonuclease, an N terminal domain of the viral polymerase (L protein) that provides capped 3 OH primers for transcription. We report TOSV endonuclease crystal structures in the apo form, in complex with a di-ketoacid inhibitor (DPBA) and in an intermediate state of inhibitor release , showing details on substrate binding and active site dynamics. The structure reveals substantial folding rearrangements absent in previously reported cap-snatching endonucleases. These include the relocation of the N terminus and the appearance of new structural motifs important for transcription and replication. The enzyme shows high activity rates comparable to other His+ cap-snatching en-donucleases. Moreover, the activity is dependent on conserved residues involved in metal ion and sub-strate binding. Altogether, these results bring new light on the structure and function of cap-snatching endonucleases and pave the way for the development of specific and broad-spectrum antivirals.
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Structural Insights into BunyaVirus Replication and Its Regulation by the vRNA Promoter
Cell, 2015Co-Authors: Piotr Gerlach, Stephen Cusack, Hélène Malet, Juan RegueraAbstract:Segmented Negative-Strand RNA Virus (sNSV) polymerases transcribe and replicate the viral RNA (vRNA) within a ribonucleoprotein particle (RNP). We present cryo-EM and X-ray structures of, respectively, apo- and vRNA bound La Crosse orthobunyaVirus (LACV) polymerase that give atomic-resolution insight into how such RNPs perform RNA synthesis. The complementary 3' and 5' vRNA extremities are sequence specifically bound in separate sites on the polymerase. The 5' end binds as a stem-loop, allosterically structuring functionally important polymerase active site loops. Identification of distinct template and product exit tunnels allows proposal of a detailed model for template-directed replication with minimal disruption to the circularised RNP. The similar overall architecture and vRNA binding of monomeric LACV to heterotrimeric influenza polymerase, despite high sequence divergence, suggests that all sNSV polymerases have a common evolutionary origin and mechanism of RNA synthesis. These results will aid development of replication inhibitors of diverse, serious human pathogenic Viruses.
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segmented negative strand RNA Virus nucleoprotein structure
Current Opinion in Virology, 2014Co-Authors: Juan Reguera, Stephen Cusack, Daniel KolakofskyAbstract:Negative strand RNA Virus (NSV) genomes are never free, but always found assembled with multiple copies of their nucleoprotein, as RNPs. A flurry of papers describing the X-ray crystal structures of several segmented NSV nucleoproteins have recently appeared. The most significant feature of these various structures is that the arms that are used to oligomerize the nucleoproteins on their genome RNAs are highly flexible, permitting these RNPs to assume virtually unlimited geometries. The structural flexibility of segmented NSV RNPs is undoubtedly important in all aspects of their biology, including genome replication and circularization, and the selection of one copy of each segment for packaging into Virus particles.
