scholarly journals Prefusion structure of human cytomegalovirus glycoprotein B and structural basis for membrane fusion

2021 ◽  
Vol 7 (10) ◽  
pp. eabf3178
Author(s):  
Yuhang Liu ◽  
Kyle P. Heim ◽  
Ye Che ◽  
Xiaoyuan Chi ◽  
Xiayang Qiu ◽  
...  
Keyword(s):  
Membrane Fusion ◽  
Human Cytomegalovirus ◽  
Transmembrane Domain ◽  
Proximal Region ◽  
Viral Envelope ◽  
Vaccine Antigen ◽  
Glycoprotein B ◽  
Structural Basis ◽  
Fusion Inhibitor ◽  
Host Cell Membrane

Human cytomegalovirus (HCMV) causes congenital disease with long-term morbidity. HCMV glycoprotein B (gB) transitions irreversibly from a metastable prefusion to a stable postfusion conformation to fuse the viral envelope with a host cell membrane during entry. We stabilized prefusion gB on the virion with a fusion inhibitor and a chemical cross-linker, extracted and purified it, and then determined its structure to 3.6-Å resolution by electron cryomicroscopy. Our results revealed the structural rearrangements that mediate membrane fusion and details of the interactions among the fusion loops, the membrane-proximal region, transmembrane domain, and bound fusion inhibitor that stabilized gB in the prefusion state. The structure rationalizes known gB antigenic sites. By analogy to successful vaccine antigen engineering approaches for other viral pathogens, the high-resolution prefusion gB structure provides a basis to develop stabilized prefusion gB HCMV vaccine antigens.

scholarly journals Structure-Function Dissection of Pseudorabies Virus Glycoprotein B Fusion Loops

2017 ◽  
Vol 92 (1) ◽  
Author(s):  
Melina Vallbracht ◽  
Delphine Brun ◽  
Matteo Tassinari ◽  
Marie-Christine Vaney ◽  
Gérard Pehau-Arnaudet ◽  
...  
Keyword(s):  
Membrane Fusion ◽  
Lipid Bilayer ◽  
Pseudorabies Virus ◽  
Molecular Model ◽  
Viral Envelope ◽  
Glycoprotein B ◽  
Interfacial Region ◽  
Dependent Manner ◽  
Host Cell Membrane ◽  
Animal Pathogens

ABSTRACTConserved across the familyHerpesviridae, glycoprotein B (gB) is responsible for driving fusion of the viral envelope with the host cell membrane for entry upon receptor binding and activation by the viral gH/gL complex. Although crystal structures of the gB ectodomains of several herpesviruses have been reported, the membrane fusion mechanism has remained elusive. Here, we report the X-ray structure of the pseudorabies virus (PrV) gB ectodomain, revealing a typical class III postfusion trimer that binds membranes via its fusion loops (FLs) in a cholesterol-dependent manner. Mutagenesis of FL residues allowed us to dissect those interacting with distinct subregions of the lipid bilayer and their roles in membrane interactions. We tested 15 gB variants for the ability to bind to liposomes and further investigated a subset of them in functional assays. We found that PrV gB FL residues Trp187, Tyr192, Phe275, and Tyr276, which were essential for liposome binding and for fusion in cellular and viral contexts, form a continuous hydrophobic patch at the gB trimer surface. Together with results reported for other alphaherpesvirus gBs, our data suggest a model in which Phe275 from the tip of FL2 protrudes deeper into the hydrocarbon core of the lipid bilayer, while the side chains of Trp187, Tyr192, and Tyr276 form a rim that inserts into the more superficial interfacial region of the membrane to catalyze the fusion process. Comparative analysis with gBs from beta- and gamma-herpesviruses suggests that this membrane interaction model is valid for gBs from all herpesviruses.IMPORTANCEHerpesviruses are common human and animal pathogens that infect cells by entering via fusion of viral and cellular membranes. Central to the membrane fusion event is glycoprotein B (gB), which is the most conserved envelope protein across the herpesvirus family. Like other viral fusion proteins, gB anchors itself in the target membrane via two polypeptide segments called fusion loops (FLs). The molecular details of how gB FLs insert into the lipid bilayer have not been described. Here, we provide structural and functional data regarding key FL residues of gB from pseudorabies virus, a porcine herpesvirus of veterinary concern, which allows us to propose, for the first time, a molecular model to understand how the initial interactions by gBs from all herpesviruses with target membranes are established.

scholarly journals Antiviral Efficacy of a Respiratory Syncytial Virus (RSV) Fusion Inhibitor in a Bovine Model of RSV Infection

2015 ◽  
Vol 59 (8) ◽  
pp. 4889-4900 ◽  
Author(s):  
Robert Jordan ◽  
Matt Shao ◽  
Richard L. Mackman ◽  
Michel Perron ◽  
Tomas Cihlar ◽  
...  
Keyword(s):  
Viral Load ◽  
Respiratory Syncytial Virus ◽  
Structural Analog ◽  
Therapeutic Benefit ◽  
Viral Envelope ◽  
Fusion Inhibitor ◽  
Lung Pathology ◽  
Host Cell Membrane ◽  
Rsv Infection ◽  
Syncytial Virus

ABSTRACTRespiratory syncytial virus (RSV) is the leading cause of bronchiolitis and pneumonia in infants. Effective treatment for RSV infection is a significant unmet medical need. While new RSV therapeutics are now in development, there are very few animal models that mimic the pathogenesis of human RSV, making it difficult to evaluate new disease interventions. Experimental infection of Holstein calves with bovine RSV (bRSV) causes a severe respiratory infection that is similar to human RSV infection, providing a relevant model for testing novel therapeutic agents. In this model, viral load is readily detected in nasal secretions by quantitative real-time PCR (qRT-PCR), and cumulative symptom scoring together with histopathology evaluations of infected tissue allow for the assessment of disease severity. The bovine RSV model was used to evaluate the antiviral activity of an RSV fusion inhibitor, GS1, which blocks virus entry by inhibiting the fusion of the viral envelope with the host cell membrane. The efficacy of GS1, a close structural analog of GS-5806 that is being developed to treat RSV infection in humans was evaluated in two randomized, blind, placebo-controlled studies in bRSV-infected calves. Intravenous administration of GS1 at 4 mg/kg of body weight/day for 7 days starting 24 h or 72 h postinoculation provided clear therapeutic benefit by reducing the viral load, disease symptom score, respiration rate, and lung pathology associated with bRSV infection. These data support the use of the bovine RSV model for evaluation of experimental therapeutics for treatment of RSV.

scholarly journals Viral Membrane Fusion and the Transmembrane Domain

Viruses ◽  
2020 ◽  
Vol 12 (7) ◽  
pp. 693 ◽  
Author(s):  
Chelsea T. Barrett ◽  
Rebecca Ellis Dutch
Keyword(s):  
Membrane Fusion ◽  
Host Cell ◽  
Fusion Proteins ◽  
Transmembrane Domain ◽  
Critical Role ◽  
Viral Fusion ◽  
Transmembrane Region ◽  
Host Cell Membrane ◽  
The Past ◽  
Viral Fusion Proteins

Initiation of host cell infection by an enveloped virus requires a viral-to-host cell membrane fusion event. This event is mediated by at least one viral transmembrane glycoprotein, termed the fusion protein, which is a key therapeutic target. Viral fusion proteins have been studied for decades, and numerous critical insights into their function have been elucidated. However, the transmembrane region remains one of the most poorly understood facets of these proteins. In the past ten years, the field has made significant advances in understanding the role of the membrane-spanning region of viral fusion proteins. We summarize developments made in the past decade that have contributed to the understanding of the transmembrane region of viral fusion proteins, highlighting not only their critical role in the membrane fusion process, but further demonstrating their involvement in several aspects of the viral lifecycle.

scholarly journals Structural Basis for the Recognition of Human Cytomegalovirus Glycoprotein B by a Neutralizing Human Antibody

2014 ◽  
Vol 10 (10) ◽  
pp. e1004377 ◽  
Author(s):  
Nadja Spindler ◽  
Uschi Diestel ◽  
Joachim D. Stump ◽  
Anna-Katharina Wiegers ◽  
Thomas H. Winkler ◽  
...  
Keyword(s):  
Human Cytomegalovirus ◽  
Glycoprotein B ◽  
Structural Basis ◽  
Human Antibody

DESIGNING DISULFIDE CYCLIC PEPTIDE AS FUSION INHIBITOR THAT TARGETS DENV ENVELOPE PROTEIN

2016 ◽  
Vol 78 (4-3) ◽  
Author(s):  
Usman Sumo Friend Tambunan ◽  
William Chua ◽  
Arli Aditya Parikesit ◽  
Djati Kerami
Keyword(s):  
Conformational Changes ◽  
Cyclic Peptides ◽  
Cyclic Peptide ◽  
Peptide Ligands ◽  
Viral Envelope ◽  
Fusion Process ◽  
Dynamics Simulation ◽  
Health Concern ◽  
Fusion Inhibitor ◽  
Host Cell Membrane

Dengue has been a major health concern and currently there is no available option to treat the infection. It is an arboviral disease caused by dengue virus (DENV), an enveloped flavivirus. DENV initiates fusion process between viral envelope and host cell membrane, transfers its viral genome into target cell and infects host. Our research is focused on designing disulfide cyclic peptides that can fit into fusion cavity and interact with fusion peptide, interrupt conformational changes and therefore inhibit the fusion process. Computational approaches were conducted to calculate the binding affinity and stability of disulfide cyclic peptide ligands with target DENV E glycoprotein. Molecular docking and molecular dynamics simulation were performed using Molecular Operating Environment 2008.10 software (MOE 2008.10). Screening of 1320 designed ligands resulted in 3 best ligands, CLREC, CYREC and CYREC that can form interaction with target cavity and peptide fusion. These ligands showed good affinity with target DENV E glycoprotein based on free binding energy and interactions. To evaluate protein-ligand stability, we performed molecular dynamic simulation. Only CLREC showed protein-ligand stability and maintained interaction between ligand and target cavity. Therefore we propose CLREC as potential DENV fusion inhibitor candidates.  

scholarly journals Coiled-Coil Domains in Glycoproteins B and H Are Involved in Human Cytomegalovirus Membrane Fusion

2004 ◽  
Vol 78 (15) ◽  
pp. 8333-8341 ◽  
Author(s):  
Matthew Lopper ◽  
Teresa Compton
Keyword(s):  
Membrane Fusion ◽  
Human Cytomegalovirus ◽  
Virus Entry ◽  
Coiled Coil ◽  
Coiled Coils ◽  
Viral Envelope ◽  
Heptad Repeat ◽  
Repeat Sequences ◽  
Human Cmv ◽  
Hsv 1

ABSTRACT Human cytomegalovirus (CMV) utilizes a complex route of entry into cells that involves multiple interactions between viral envelope proteins and cellular receptors. Three conserved viral glycoproteins, gB, gH, and gL, are required for CMV-mediated membrane fusion, but little is known of how these proteins cooperate during entry (E. R. Kinzler and T. Compton, submitted for publication). The goal of this study was to begin defining the molecular mechanisms that underlie membrane fusion mediated by herpesviruses. We identified heptad repeat sequences predicted to form alpha-helical coiled coils in two glycoproteins required for fusion, gB and gH. Peptides derived from gB and gH containing the heptad repeat sequences inhibited virus entry when introduced coincident with virus inoculation onto cells or when mixed with virus prior to inoculation. Neither peptide affected binding of CMV to fibroblasts, suggesting that the peptides inhibit membrane fusion. Both gB and gH coiled-coil peptides blocked entry of several laboratory-adapted and clinical strains of human CMV, but neither peptide affected entry of murine CMV or herpes simplex virus type 1 (HSV-1). Although murine CMV and HSV-1 gB and gH have heptad repeat regions, the ability of human CMV gB and gH peptides to inhibit virus entry correlates with the specific residues that comprise the heptad repeat region. The ability of gB and gH coiled-coil peptides to inhibit virus entry independently of cell contact suggests that the coiled-coil regions of gB and gH function differently from those of class I, single-component fusion proteins. Taken together, these data support a critical role for alpha-helical coiled coils in gB and gH in the entry pathway of CMV.

scholarly journals Enfuvirtide (T20)-Based Lipopeptide Is a Potent HIV-1 Cell Fusion Inhibitor: Implications for Viral Entry and Inhibition

2017 ◽  
Vol 91 (18) ◽  
Author(s):  
Xiaohui Ding ◽  
Xiujuan Zhang ◽  
Huihui Chong ◽  
Yuanmei Zhu ◽  
Huamian Wei ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Combination Therapy ◽  
Membrane Fusion ◽  
Cell Fusion ◽  
Peptide Sequence ◽  
Structural Basis ◽  
Fusion Inhibitor ◽  
Binding Modes ◽  
Hiv 1 ◽  
Cell Cell

ABSTRACT The peptide drug enfuvirtide (T20) is the only viral fusion inhibitor used in combination therapy for HIV-1 infection, but it has relatively low antiviral activity and easily induces drug resistance. Emerging studies demonstrate that lipopeptide-based fusion inhibitors, such as LP-11 and LP-19, which mainly target the gp41 pocket site, have greatly improved antiviral potency and in vivo stability. In this study, we focused on developing a T20-based lipopeptide inhibitor that lacks pocket-binding sequence and targets a different site. First, the C-terminal tryptophan-rich motif (TRM) of T20 was verified to be essential for its target binding and inhibition; then, a novel lipopeptide, termed LP-40, was created by replacing the TRM with a fatty acid group. LP-40 showed markedly enhanced binding affinity for the target site and dramatically increased inhibitory activity on HIV-1 membrane fusion, entry, and infection. Unlike LP-11 and LP-19, which required a flexible linker between the peptide sequence and the lipid moiety, addition of a linker to LP-40 sharply reduced its potency, implying different binding modes with the extended N-terminal helices of gp41. Also, interestingly, LP-40 showed more potent activity than LP-11 in inhibiting HIV-1 Env-mediated cell-cell fusion while it was less active than LP-11 in inhibiting pseudovirus entry, and the two inhibitors displayed synergistic antiviral effects. The crystal structure of LP-40 in complex with a target peptide revealed their key binding residues and motifs. Combined, our studies have not only provided a potent HIV-1 fusion inhibitor, but also revealed new insights into the mechanisms of viral inhibition. IMPORTANCE T20 is the only membrane fusion inhibitor available for treatment of viral infection; however, T20 requires high doses and has a low genetic barrier for resistance, and its inhibitory mechanism and structural basis remain unclear. Here, we report the design of LP-40, a T20-based lipopeptide inhibitor that has greatly improved anti-HIV activity and is a more potent inhibitor of cell-cell fusion than of cell-free virus infection. The binding modes of two classes of membrane-anchoring lipopeptides (LP-40 and LP-11) verify the current fusion model in which an extended prehairpin structure bridges the viral and cellular membranes, and their complementary effects suggest a vital strategy for combination therapy of HIV-1 infection. Moreover, our understanding of the mechanism of action of T20 and its derivatives benefits from the crystal structure of LP-40.

scholarly journals Influenza A H1 and H3 Transmembrane Domains Interact Differently with Each Other and with Surrounding Membrane Lipids

Viruses ◽  
2020 ◽  
Vol 12 (12) ◽  
pp. 1461
Author(s):  
Szymon Kubiszewski-Jakubiak ◽  
Remigiusz Worch
Keyword(s):  
Host Cell ◽  
Influenza A ◽  
Transmembrane Domain ◽  
Membrane Lipids ◽  
Transmembrane Protein ◽  
Accessible Surface Area ◽  
Amino Acid Sequences ◽  
Viral Envelope ◽  
Phylogenetic Groups ◽  
Host Cell Membrane

Hemagglutinin (HA) is a class I viral membrane fusion protein, which is the most abundant transmembrane protein on the surface of influenza A virus (IAV) particles. HA plays a crucial role in the recognition of the host cell, fusion of the viral envelope and the host cell membrane, and is the major antigen in the immune response during the infection. Mature HA organizes in homotrimers consisting of a sequentially highly variable globular head and a relatively conserved stalk region. Every HA monomer comprises a hydrophilic ectodomain, a pre-transmembrane domain (pre-TMD), a hydrophobic transmembrane domain (TMD), and a cytoplasmic tail (CT). In recent years the effect of the pre-TMD and TMD on the structure and function of HA has drawn some attention. Using bioinformatic tools we analyzed all available full-length amino acid sequences of HA from 16 subtypes across various host species. We calculated several physico-chemical parameters of HA pre-TMDs and TMDs including accessible surface area (ASA), average hydrophobicity (Hav), and the hydrophobic moment (µH). Our data suggests that distinct differences in these parameters between the two major phylogenetic groups, represented by H1 and H3 subtypes, could have profound effects on protein–lipid interactions, trimer formation, and the overall HA ectodomain orientation and antigen exposure.

scholarly journals Characterization of Human Cytomegalovirus Glycoprotein-Induced Cell-Cell Fusion

2005 ◽  
Vol 79 (12) ◽  
pp. 7827-7837 ◽  
Author(s):  
Eric R. Kinzler ◽  
Teresa Compton
Keyword(s):  
Cell Lines ◽  
Human Cytomegalovirus ◽  
Neutralizing Antibodies ◽  
Syncytium Formation ◽  
Viral Envelope ◽  
Host Cell Membrane ◽  
Cellular Factors ◽  
A Cell ◽  
Cell Cell

ABSTRACT Human cytomegalovirus (CMV) infection is dependent on the functions of structural glycoproteins at multiple stages of the viral life cycle. These proteins mediate the initial attachment and fusion events that occur between the viral envelope and a host cell membrane, as well as virion-independent cell-cell spread of the infection. Here we have utilized a cell-based fusion assay to identify the fusogenic glycoproteins of CMV. To deliver the glycoprotein genes to various cell lines, we constructed recombinant retroviruses encoding gB, gH, gL, and gO. Cells expressing individual CMV glycoproteins did not form multinucleated syncytia. Conversely, cells expressing gH/gL showed pronounced syncytium formation, although expression of gH or gL alone had no effect. Anti-gH neutralizing antibodies prevented syncytium formation. Coexpression of gB and/or gO with gH/gL did not yield detectably increased numbers of syncytia. For verification, these results were recapitulated in several cell lines. Additionally, we found that fusion was cell line dependent, as nonimmortalized fibroblast strains did not fuse under any conditions. Thus, the CMV gH/gL complex has inherent fusogenic activity that can be measured in certain cell lines; however, fusion in fibroblast strains may involve a more complex mechanism involving additional viral and/or cellular factors.

scholarly journals Mycobacterium Survival Strategy Translated to Develop a Lipo-Peptide Based Fusion Inhibitor

2020 ◽  
Author(s):  
Avijit Sardar ◽  
Aritraa Lahiri ◽  
Amirul Islam Mallick ◽  
Pradip Kumar Tarafdar
Keyword(s):  
Membrane Fusion ◽  
Host Cell ◽  
Broad Spectrum ◽  
Antiviral Agent ◽  
Host Cells ◽  
Peptide Sequence ◽  
Fusion Inhibitor ◽  
Host Cell Membrane ◽  
Unique Structural Feature ◽  
Host Cell Membranes

The entry of enveloped viruses requires fusion of viral and host cell membranes. An effective fusion inhibitor aiming at impeding such virus-host cell membrane fusion may emerge as a broad-spectrum antiviral agent to neutralize the infection from an increasing diversity of harmful new viruses. Mycobacterium survives inside the phagosome of the host cells by inhibiting phagosome-lysosome fusion with the help of a coat protein coronin 1. Structural analysis of coronin 1 and other WD40-repeat containing protein suggest that the tryptophan-aspartic acid (WD) sequence is placed at distorted β-meander motif (more exposed) whereas the WD resides in regular β-meander motif in other WD40 proteins. The unique structural feature of coronin 1 was explored to identify a simple lipo-peptide sequence (lipid-WD), which effectively inhibit the membrane fusion by increasing interfacial order and decreasing water penetration, surface potential. The effective fusion inhibitory role of mycobacterium inspired lipo-dipeptide was applied to combat type 1 influenza virus (H1N1) infection as a ‘broad spectrum’ antiviral agent.<br>

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