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Stephen C. Harrison - One of the best experts on this subject based on the ideXlab platform.
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mechanism of membrane Fusion induced by vesicular stomatitis virus g protein
Proceedings of the National Academy of Sciences of the United States of America, 2017Co-Authors: Irene S Kim, Stephen C. Harrison, Simon Jenni, Megan L Stanifer, Eatai Roth, Sean P J Whelan, Antoine M Van OijenAbstract:The glycoProteins (G Proteins) of vesicular stomatitis virus (VSV) and related rhabdoviruses (e.g., rabies virus) mediate both cell attachment and membrane Fusion. The reversibility of their fusogenic conformational transitions differentiates them from many other low-pH-induced Viral Fusion Proteins. We report single-virion Fusion experiments, using methods developed in previous publications to probe Fusion of influenza and West Nile viruses. We show that a three-stage model fits VSV single-particle Fusion kinetics: (i) reversible, pH-dependent, G-protein conformational change from the known preFusion conformation to an extended, monomeric intermediate; (ii) reversible trimerization and clustering of the G-protein Fusion loops, leading to an extended intermediate that inserts the Fusion loops into the target-cell membrane; and (iii) folding back of a cluster of extended trimers into their postFusion conformations, bringing together the Viral and cellular membranes. From simulations of the kinetic data, we conclude that the critical number of G-protein trimers required to overcome membrane resistance is 3 to 5, within a contact zone between the virus and the target membrane of 30 to 50 trimers. This sequence of conformational events is similar to those shown to describe Fusion by influenza virus hemagglutinin (a “class I” fusogen) and West Nile virus envelope protein (“class II”). Our study of VSV now extends this description to “class III” Viral Fusion Proteins, showing that reversibility of the low-pH-induced transition and architectural differences in the Fusion Proteins themselves do not change the basic mechanism by which they catalyze membrane Fusion.
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Viral membrane Fusion
Virology, 2015Co-Authors: Stephen C. HarrisonAbstract:Membrane Fusion is an essential step when enveloped viruses enter cells. Lipid bilayer Fusion requires catalysis to overcome a high kinetic barrier; Viral Fusion Proteins are the agents that fulfill this catalytic function. Despite a variety of molecular architectures, these Proteins facilitate Fusion by essentially the same generic mechanism. Stimulated by a signal associated with arrival at the cell to be infected (e.g., receptor or co-receptor binding, proton binding in an endosome), they undergo a series of conformational changes. A hydrophobic segment (a "Fusion loop" or "Fusion peptide") engages the target-cell membrane and collapse of the bridging intermediate thus formed draws the two membranes (virus and cell) together. We know of three structural classes for Viral Fusion Proteins. Structures for both pre- and postFusion conformations of illustrate the beginning and end points of a process that can be probed by single-virion measurements of Fusion kinetics.
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peptide inhibitors of dengue virus entry target a late stage Fusion intermediate
PLOS Pathogens, 2010Co-Authors: Aaron G Schmidt, Stephen C. Harrison, Priscilla L YangAbstract:The mechanism of membrane Fusion by “class II” Viral Fusion Proteins follows a pathway that involves large-scale domain rearrangements of the envelope glycoprotein (E) and a transition from dimers to trimers. The rearrangement is believed to proceed by an outward rotation of the E ectodomain after loss of the dimer interface, followed by a reassociation into extended trimers. The ∼55-aa-residue, membrane proximal “stem” can then zip up along domain II, bringing together the transmembrane segments of the C-terminus and the Fusion loops at the tip of domain II. We find that peptides derived from the stem of dengue-virus E bind stem-less E trimer, which models a conformational intermediate. In vitro assays demonstrate that these peptides specifically block Viral Fusion. The peptides inhibit infectivity with potency proportional to their affinity for the conformational intermediate, even when free peptide is removed from a preincubated inoculum before infecting cells. We conclude that peptides bind virions before attachment and are carried with virions into endosomes, the compartment in which acidification initiates Fusion. Binding depends on particle dynamics, as there is no inhibition of infectivity if preincubation and separation are at 4°C rather than 37°C. We propose a two-step model for the mechanism of Fusion inhibition. Targeting a Viral entry pathway can be an effective way to block infection. Our data, which support and extend proposed mechanisms for how the E conformational change promotes membrane Fusion, suggest strategies for inhibiting flavivirus entry.
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Viral membrane Fusion
Nature Structural & Molecular Biology, 2008Co-Authors: Stephen C. HarrisonAbstract:Infection by viruses having lipid-bilayer envelopes proceeds through Fusion of the Viral membrane with a membrane of the target cell. Viral 'Fusion Proteins' facilitate this process. They vary greatly in structure, but all seem to have a common mechanism of action, in which a ligand-triggered, large-scale conformational change in the Fusion protein is coupled to apposition and merger of the two bilayers. We describe three examples--the influenza virus hemagglutinin, the flavivirus E protein and the vesicular stomatitis virus G protein--in some detail, to illustrate the ways in which different structures have evolved to implement this common mechanism. Fusion inhibitors can be effective antiViral agents.
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mechanism of membrane Fusion by Viral envelope Proteins
Advances in Virus Research, 2005Co-Authors: Stephen C. HarrisonAbstract:Publisher Summary Enveloped viruses enter cells by fusing their lipid bilayer membrane with a cellular membrane. Most Viral Fusion Proteins require priming by proteolytic processing, either of the Fusion protein itself or of an accompanying protein. The priming step, which often occurs during transport of the Fusion protein to the cell surface but may also occur extracellularly, then prepares the Fusion protein for triggering by events that accompany attachment and uptake. Two classes of Viral Fusion Proteins have been identified so far by structural studies. The Fusion of two bilayers that these Proteins catalyze is likely to proceed by the same pathway in both cases. That is, these Proteins are like enzymes that have different structures but that still catalyze the same chemical reaction. It is found that bilayer Fusion reaction is common to all the enveloped Viral entry pathways. It is believed to pass through an intermediate known as a “hemiFusion stalk.”
Theodore S Jardetzky - One of the best experts on this subject based on the ideXlab platform.
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Class III Viral membrane Fusion Proteins.
Advances in experimental medicine and biology, 2011Co-Authors: Marija Backovic, Theodore S JardetzkyAbstract:Members of class III of Viral Fusion Proteins share common structural features and molecular architecture, although they belong to evolutionary distant viruses and carry no sequence homology. Based of the experimentally determined three-dimensional structures of their ectodomains, glycoprotein B (gB) of herpesviruses, G protein of rhabdoviruses and glycoprotein 64 (gp64) of baculoviruses have been identified as class III Fusion Proteins. The structures are proposed to represent post-Fusion conformations, and they reveal trimeric, elongated, rod-like molecules, with each protomer being composed of five domains. Sequences which interact with target membranes and form the Fusion peptides are located in two loops found at one end of the molecule. Class III Fusion Proteins are embedded in Viral envelope with the principal function of catalyzing Fusion of Viral and cellular membranes, an event that is essential for infection to occur. In addition, they have been implicated in processes such as attachment to target cells and Viral maturation. G protein is the only class III Fusion protein for which structures of both pre- and post-Fusion states have been determined, shedding light on the mechanism involved in the conformational change and membrane Fusion. Whether similar structural organization of class III Fusion Proteins translates into a common mechanism involved in carrying out membrane Fusion remains to be investigated.
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Class III Viral membrane Fusion Proteins.
Current opinion in structural biology, 2009Co-Authors: Marija Backovic, Theodore S JardetzkyAbstract:Accumulating structural studies of Viral Fusion glycoProteins have revealed unanticipated structural relationships between unrelated virus families and allowed the grouping of these membrane fusogens into three distinct classes. Here we review the newly identified group of class III Viral Fusion Proteins, whose members include Fusion Proteins from rhabdoviruses, herpesviruses, and baculoviruses. While clearly related in structure, the class III Viral Fusion Proteins exhibit distinct structural features in their architectures as well as in their membrane interacting Fusion loops, which are likely related to their virus-specific differences in cellular entry. Further study of the similarities and differences in the class III Viral Fusion glycoProteins may provide greater insights into protein:membrane interactions that are key to promoting efficient bilayer Fusion during virus entry.
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characterization of ebv gb indicates properties of both class i and class ii Viral Fusion Proteins
Virology, 2007Co-Authors: Marija Backovic, Robert A Lamb, George P Leser, Richard Longnecker, Theodore S JardetzkyAbstract:To gain insight into Epstein-Barr virus (EBV) glycoprotein B (gB), recombinant, secreted variants were generated. The role of putative transmembrane regions, the proteolytic processing and the oligomerization state of the gB variants were investigated. Constructs containing 2 of 3 C-terminal hydrophobic regions were secreted, indicating that these do not act as transmembrane anchors. The efficiency of cleavage of the gB furin site was found to depend on the nature of C-terminus. All of the gB constructs formed rosette structures reminiscent of the postFusion aggregates formed by other Viral Fusion Proteins. However, substitution of putative Fusion loop residues, WY(112-113) and WLIY(193-196), with less hydrophobic amino acids from HSV-1 gB, produced trimeric protein and abrogated the ability of the EBV gB ectodomains to form rosettes. These data demonstrate biochemical features of EBV gB that are characteristic of other class I and class II Viral Fusion Proteins, but not of HSV-1 gB.
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structural basis of Viral invasion lessons from paramyxovirus f
Current Opinion in Structural Biology, 2007Co-Authors: Robert A Lamb, Theodore S JardetzkyAbstract:The structures of glycoProteins that mediate enveloped virus entry into cells have revealed dramatic structural changes that accompany membrane Fusion and provided mechanistic insights into this process. The group of class I Viral Fusion Proteins includes the influenza hemagglutinin, paramyxovirus F, HIV env, and other mechanistically related fusogens, but these Proteins are unrelated in sequence and exhibit clearly distinct structural features. Recently determined crystal structures of the paramyxovirus F protein in two conformations, representing pre-Fusion and post-Fusion states, reveal a novel protein architecture that undergoes large-scale, irreversible refolding during membrane Fusion, extending our understanding of this diverse group of membrane Fusion machines.
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structure of the uncleaved ectodomain of the paramyxovirus hpiv3 Fusion protein
Proceedings of the National Academy of Sciences of the United States of America, 2005Co-Authors: Reay G Paterson, Robert A Lamb, Theodore S JardetzkyAbstract:Class I Viral Fusion Proteins share common mechanistic and structural features but little sequence similarity. Structural insights into the protein conformational changes associated with membrane Fusion are based largely on studies of the influenza virus hemagglutinin in pre- and postFusion conformations. Here, we present the crystal structure of the secreted, uncleaved ectodomain of the paramyxovirus, human parainfluenza virus 3 Fusion (F) protein, a member of the class I Viral Fusion protein group. The secreted human parainfluenza virus 3 F forms a trimer with distinct head, neck, and stalk regions. Unexpectedly, the structure reveals a six-helix bundle associated with the postFusion form of F, suggesting that the anchor-minus ectodomain adopts a conformation largely similar to the postFusion state. The transmembrane anchor domains of F may therefore profoundly influence the folding energetics that establish and maintain a metastable, preFusion state.
Peter J M Rottier - One of the best experts on this subject based on the ideXlab platform.
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cryo electron microscopy structure of a coronavirus spike glycoprotein trimer
Nature, 2016Co-Authors: Alexandra C Walls, Felix A Rey, Berend Jan Bosch, Peter J M Rottier, Alejandra M Tortorici, Brandon Frenz, Frank Dimaio, David VeeslerAbstract:The tremendous pandemic potential of coronaviruses was demonstrated twice in the past few decades by two global outbreaks of deadly pneumonia. Entry of coronaviruses into cells is mediated by the transmembrane spike glycoprotein S, which forms a trimer carrying receptor-binding and membrane Fusion functions. S also contains the principal antigenic determinants and is the target of neutralizing antibodies. Here we present the structure of a mouse coronavirus S trimer ectodomain determined at 4.0 A resolution by single particle cryo-electron microscopy. It reveals the metastable pre-Fusion architecture of S and highlights key interactions stabilizing it. The structure shares a common core with paramyxovirus F Proteins, implicating mechanistic similarities and an evolutionary connection between these Viral Fusion Proteins. The accessibility of the highly conserved Fusion peptide at the periphery of the trimer indicates potential vaccinology strategies to elicit broadly neutralizing antibodies against coronaviruses. Finally, comparison with crystal structures of human coronavirus S domains allows rationalization of the molecular basis for species specificity based on the use of spatially contiguous but distinct domains.
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cathepsin l functionally cleaves the severe acute respiratory syndrome coronavirus class i Fusion protein upstream of rather than adjacent to the Fusion peptide
Journal of Virology, 2008Co-Authors: Berend Jan Bosch, Willem Bartelink, Peter J M RottierAbstract:Unlike other class I Viral Fusion Proteins, spike Proteins on severe acute respiratory syndrome coronavirus virions are uncleaved. As we and others have demonstrated, infection by this virus depends on cathepsin proteases present in endosomal compartments of the target cell, suggesting that the spike protein acquires its Fusion competence by cleavage during cell entry rather than during virion biogenesis. Here we demonstrate that cathepsin L indeed activates the membrane Fusion function of the spike protein. Moreover, cleavage was mapped to the same region where, in coronaviruses carrying furin-activated spikes, the receptor binding subunit of the protein is separated from the membrane-anchored Fusion subunit.
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severe acute respiratory syndrome coronavirus sars cov infection inhibition using spike protein heptad repeat derived peptides
Proceedings of the National Academy of Sciences of the United States of America, 2004Co-Authors: Berend Jan Bosch, Byron E E Martina, Ruurd Van Der Zee, Jean Lepault, Bert Jan Haijema, Cees Versluis, Albert J R Heck, Raoul J De Groot, Albert D M E Osterhaus, Peter J M RottierAbstract:The coronavirus SARS-CoV is the primary cause of the life-threatening severe acute respiratory syndrome (SARS). With the aim of developing therapeutic agents, we have tested peptides derived from the membrane-proximal (HR2) and membrane-distal (HR1) heptad repeat region of the spike protein as inhibitors of SARS-CoV infection of Vero cells. It appeared that HR2 peptides, but not HR1 peptides, were inhibitory. Their efficacy was, however, significantly lower than that of corresponding HR2 peptides of the murine coronavirus mouse hepatitis virus (MHV) in inhibiting MHV infection. Biochemical and electron microscopical analyses showed that, when mixed, SARS-CoV HR1 and HR2 peptides assemble into a six-helix bundle consisting of HR1 as a central triple-stranded coiled coil in association with three HR2 α-helices oriented in an antiparallel manner. The stability of this complex, as measured by its resistance to heat dissociation, appeared to be much lower than that of the corresponding MHV complex, which may explain the different inhibitory potencies of the HR2 peptides. Analogous to other class I Viral Fusion Proteins, the six-helix complex supposedly represents a postFusion conformation that is formed after insertion of the Fusion peptide, proposed here for coronaviruses to be located immediately upstream of HR1, into the target membrane. The resulting close apposition of Fusion peptide and spike transmembrane domain facilitates membrane Fusion. The inhibitory potency of the SARS-CoV HR2-peptides provides an attractive basis for the development of a therapeutic drug for SARS.
Gary R Whittaker - One of the best experts on this subject based on the ideXlab platform.
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A Fluorogenic Peptide Cleavage Assay to Screen for Proteolytic Activity: Applications for coronavirus spike protein activation.
Journal of visualized experiments : JoVE, 2019Co-Authors: Javier A. Jaimes, Gary R Whittaker, Jean K. Millet, Monty E. Goldstein, Marco R. StrausAbstract:Enveloped viruses such as coronaviruses or influenza virus require proteolytic cleavage of their Fusion protein to be able to infect the host cell. Often viruses exhibit cell and tissue tropism and are adapted to specific cell or tissue proteases. Moreover, these viruses can introduce mutations or insertions into their genome during replication that may affect the cleavage, and thus can contribute to adaptations to a new host. Here, we present a fluorogenic peptide cleavage assay that allows a rapid screening of peptides mimicking the cleavage site of Viral Fusion Proteins. The technique is very flexible and can be used to investigate the proteolytic activity of a single protease on many different substrates, and in addition, it also allows exploration of the activity of multiple proteases on one or more peptide substrates. In this study, we used peptides mimicking the cleavage site motifs of the coronavirus spike protein. We tested human and camel derived Middle East Respiratory Syndrome coronaviruses (MERS-CoV) to demonstrate that single and double substitutions in the cleavage site can alter the activity of furin and dramatically change cleavage efficiency. We also used this method in combination with bioinformatics to test furin cleavage activity of feline coronavirus spike Proteins from different serotypes and strains. This peptide-based method is less labor- and time intensive than conventional methods used for the analysis of proteolytic activity for viruses, and results can be obtained within a single day.
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Mechanisms of coronavirus cell entry mediated by the Viral spike protein
Viruses, 2012Co-Authors: Sandrine Belouzard, Jean Millet, Beth N. Licitra, Gary R WhittakerAbstract:Coronaviruses are enveloped positive-stranded RNA viruses that replicate in the cytoplasm. To deliver their nucleocapsid into the host cell, they rely on the Fusion of their envelope with the host cell membrane. The spike glycoprotein (S) mediates virus entry and is a primary determinant of cell tropism and pathogenesis. It is classified as a class I Fusion protein, and is responsible for binding to the receptor on the host cell as well as mediating the Fusion of host and Viral membranes-A process driven by major conformational changes of the S protein. This review discusses coronavirus entry mechanisms focusing on the different triggers used by coronaviruses to initiate the conformational change of the S protein: receptor binding, low pH exposure and proteolytic activation. We also highlight commonalities between coronavirus S Proteins and other class I Viral Fusion Proteins, as well as distinctive features that confer distinct tropism, pathogenicity and host interspecies transmission characteristics to coronaviruses.
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characterization of a highly conserved domain within the severe acute respiratory syndrome coronavirus spike protein s2 domain with characteristics of a Viral Fusion peptide
Journal of Virology, 2009Co-Authors: Ikenna G Madu, Sandrine Belouzard, Shoshannah L Roth, Gary R WhittakerAbstract:Many Viral Fusion Proteins are primed by proteolytic cleavage near their Fusion peptides. While the coronavirus (CoV) spike (S) protein is known to be cleaved at the S1/S2 boundary, this cleavage site is not closely linked to a Fusion peptide. However, a second cleavage site has been identified in the severe acute respiratory syndrome CoV (SARS-CoV) S2 domain (R797). Here, we investigated whether this internal cleavage of S2 exposes a Viral Fusion peptide. We show that the residues immediately C-terminal to the SARS-CoV S2 cleavage site SFIEDLLFNKVTLADAGF are very highly conserved across all CoVs. Mutagenesis studies of these residues in SARS-CoV S, followed by cell-cell Fusion and pseudotyped virion infectivity assays, showed a critical role for residues L803, L804, and F805 in membrane Fusion. Mutation of the most N-terminal residue (S798) had little or no effect on membrane Fusion. Biochemical analyses of synthetic peptides corresponding to the proposed S2 Fusion peptide also showed an important role for this region in membrane Fusion and indicated the presence of α-helical structure. We propose that proteolytic cleavage within S2 exposes a novel internal Fusion peptide for SARS-CoV S, which may be conserved across the Coronaviridae.
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molecular architecture of the bipartite Fusion loops of vesicular stomatitis virus glycoprotein g a class iii Viral Fusion protein
Journal of Biological Chemistry, 2008Co-Authors: Sandrine Belouzard, Gary R WhittakerAbstract:Abstract The glycoprotein of vesicular stomatitis virus (VSV G) mediates Fusion of the Viral envelope with the host cell, with the conformational changes that mediate VSV G Fusion activation occurring in a reversible, low pH-dependent manner. Based on its novel structure, VSV G has been classified as class III Viral Fusion protein, having a predicted bipartite Fusion domain comprising residues Trp-72, Tyr-73, Tyr-116, and Ala-117 that interacts with the host cell membrane to initiate the Fusion reaction. Here, we carried out a systematic mutagenesis study of the predicted VSV G Fusion loops, to investigate the functional role of the Fusion domain. Using assays of low pH-induced cell-cell Fusion and infection studies of mutant VSV G incorporated into Viral particles, we show a fundamental role for the bipartite Fusion domain. We show that Trp-72 is a critical residue for VSV G-mediated membrane Fusion. Trp-72 could only tolerate mutation to a phenylalanine residue, which allowed only limited Fusion. Tyr-73 and Tyr-116 could be mutated to other aromatic residues without major effect but could not tolerate any other substitution. Ala-117 was a less critical residue, with only charged residues unable to allow Fusion activation. These data represent a functional analysis of predicted bipartite Fusion loops of VSV G, a founder member of the class III family of Viral Fusion Proteins.
Robert F Garry - One of the best experts on this subject based on the ideXlab platform.
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proteomics computational analyses suggest that the envelope glycoProteins of segmented jingmen flavi like viruses are class ii Viral Fusion Proteins b penetrenes with mucin like domains
Viruses, 2020Co-Authors: Courtney E Garry, Robert F GarryAbstract:Jingmen viruses are newly described segmented flavi-like viruses that have a worldwide distribution in ticks and have been associated with febrile illnesses in humans. Computational analyses were used to predict that Jingmen flavi-like virus glycoProteins have structural features of class II Viral Fusion Proteins, including an ectodomain consisting of beta-sheets and short alpha-helices, a Fusion peptide with interfacial hydrophobicity and a three-domain architecture. Jingmen flavi-like virus glycoProteins have a sequence enriched in serine, threonine, and proline at the amino terminus, which is a feature of mucin-like domains. Several of the serines and threonines are predicted be modified by the addition of O-linked glycans. Some of the glycoProteins are predicted to have an additional mucin-like domain located prior to the transmembrane anchor, whereas others are predicted to have a stem consisting of two alpha-helices. The flavivirus envelope protein and Jingmen flavi-virus glycoProteins may have diverged from a common class II precursor glycoprotein with a mucin-like domain or domains acquired after divergence.
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proteomics computational analyses suggest that the antennavirus glycoprotein complex includes a class i Viral Fusion protein α penetrene with an internal zinc binding domain and a stable signal peptide
Viruses, 2019Co-Authors: Courtney E Garry, Robert F GarryAbstract:A metatranscriptomic study of RNA viruses in cold-blooded vertebrates identified two related viruses from frogfish (Antennarius striatus) that represent a new genus Antennavirus in the family Arenaviridae (Order: BunyaVirales). Computational analyses were used to identify features common to class I Viral Fusion Proteins (VFPs) in antennavirus glycoProteins, including an N-terminal Fusion peptide, two extended alpha-helices, an intrahelical loop, and a carboxyl terminal transmembrane domain. Like mammarenavirus and hartmanivirus glycoProteins, the antennavirus glycoProteins have an intracellular zinc-binding domain and a long virion-associated stable signal peptide (SSP). The glycoProteins of reptarenaviruses are also class I VFPs, but do not contain zinc-binding domains nor do they encode SSPs. Divergent evolution from a common progenitor potentially explains similarities of antennavirus, mammarenavirus, and hartmanivirus glycoProteins, with an ancient recombination event resulting in a divergent reptarenavirus glycoprotein.
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Proteomics computational analyses suggest that the bornavirus glycoprotein is a class III Viral Fusion protein (γ penetrene)
Virology Journal, 2009Co-Authors: Courtney E Garry, Robert F GarryAbstract:Background Borna disease virus (BDV) is the type member of the Bornaviridae, a family of viruses that induce often fatal neurological diseases in horses, sheep and other animals, and have been proposed to have roles in certain psychiatric diseases of humans. The BDV glycoprotein (G) is an extensively glycosylated protein that migrates with an apparent molecular mass of 84,000 to 94,000 kilodaltons (kDa). BDV G is post-translationally cleaved by the cellular subtilisin-like protease furin into two subunits, a 41 kDa amino terminal protein GP1 and a 43 kDa carboxyl terminal protein GP2. Results Class III Viral Fusion Proteins (VFP) encoded by members of the Rhabdoviridae, Herpesviridae and Baculoviridae have an internal Fusion domain comprised of beta sheets, other beta sheet domains, an extended alpha helical domain, a membrane proximal stem domain and a carboxyl terminal anchor. Proteomics computational analyses suggest that the structural/functional motifs that characterize class III VFP are located collinearly in BDV G. Structural models were established for BDV G based on the post-Fusion structure of a prototypic class III VFP, vesicular stomatitis virus glycoprotein (VSV G). Conclusion These results suggest that G encoded by members of the Bornavirdae are class III VFPs (gamma-penetrenes).
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peptide inhibitors of dengue virus and west nile virus infectivity
Virology Journal, 2005Co-Authors: Yancey M Hrobowski, Robert F Garry, Scott F MichaelAbstract:Viral Fusion Proteins mediate cell entry by undergoing a series of conformational changes that result in virion-target cell membrane Fusion. Class I Viral Fusion Proteins, such as those encoded by influenza virus and human immunodeficiency virus (HIV), contain two prominent alpha helices. Peptides that mimic portions of these alpha helices inhibit structural rearrangements of the Fusion Proteins and prevent Viral infection. The envelope glycoprotein (E) of flaviviruses, such as West Nile virus (WNV) and dengue virus (DENV), are class II Viral Fusion Proteins comprised predominantly of beta sheets. We used a physio-chemical algorithm, the Wimley-White interfacial hydrophobicity scale (WWIHS) [1] in combination with known structural data to identify potential peptide inhibitors of WNV and DENV infectivity that target the Viral E protein. Viral inhibition assays confirm that several of these peptides specifically interfere with target virus entry with 50% inhibitory concentration (IC50) in the 10 μM range. Inhibitory peptides similar in sequence to domains with a significant WWIHS scores, including domain II (IIb), and the stem domain, were detected. DN59, a peptide corresponding to the stem domain of DENV, inhibited infection by DENV (>99% inhibition of plaque formation at a concentrations of 99% inhibition at <25 μM) was also demonstrated with DN59. However, a potent WNV inhibitory peptide, WN83, which corresponds to WNV E domain IIb, did not inhibit infectivity by DENV. Additional results suggest that these inhibitory peptides are noncytotoxic and act in a sequence specific manner. The inhibitory peptides identified here can serve as lead compounds for the development of peptide drugs for flavivirus infection.
