scholarly journals Characterization of the Prototype Foamy Virus Envelope Glycoprotein Receptor-Binding Domain

2006 ◽  
Vol 80 (16) ◽  
pp. 8158-8167 ◽  
Author(s):  
Anja Duda ◽  
Daniel Lüftenegger ◽  
Thomas Pietschmann ◽  
Dirk Lindemann
Keyword(s):  
Host Cell ◽  
Receptor Binding ◽  
Foamy Virus ◽  
Glycosylation Site ◽  
Binding Domain ◽  
Leader Peptide ◽  
Target Cells ◽  
Receptor Binding Domain ◽  
Cell Binding ◽  
Extracellular Domains

ABSTRACT The foamy virus (FV) glycoprotein precursor gp130Env undergoes a highly unusual biosynthesis, resulting in the generation of three particle-associated, mature subunits, leader peptide (LP), surface (SU), and transmembrane (TM). Little structural and functional information on the extracellular domains of FV Env is available. In this study, we characterized the prototype FV (PFV) Env receptor-binding domain (RBD) by flow cytometric analysis of recombinant PFV Env immunoadhesin binding to target cells. The extracellular domains of the C-terminal TM subunit as well as targeting of the recombinant immunoadhesins by the cognate LP to the secretory pathway were dispensable for target cell binding, suggesting that the PFV Env RBD is contained within the SU subunit. N- and C-terminal deletion analysis of the SU domain revealed a minimal continuous RBD spanning amino acids (aa) 225 to 555; however, internal deletions covering the region from aa 397 to 483, but not aa 262 to 300 or aa 342 to 396, were tolerated without significant influence on host cell binding. Analysis of individual cysteine point mutants in PFV SU revealed that only most of those located in the nonessential region from aa 397 to 483 retained residual binding activity. Interestingly, analysis of various N-glycosylation site mutants suggests an important role of carbohydrate chain attachment to N391, either for direct interaction with the receptor or for correct folding of the PFV Env RBD. Taken together, these results suggest that a bipartite sequence motif spanning aa 225 to 396 and aa 484 to 555 is essential for formation of the PFV Env RBD, with N-glycosylation site at position 391 playing a crucial role for host cell binding.

scholarly journals A modular molecular framework for quickly estimating the binding affinity of the spike protein of SARS-CoV-2 variants for ACE2, in presence of mutations at the spike receptor binding domain.

2021 ◽  
Author(s):  
Vincenzo Tragni ◽  
Francesca Preziusi ◽  
Luna Laera ◽  
Angelo Onofrio ◽  
Simona Todisco ◽  
...  
Keyword(s):  
Host Cell ◽  
Receptor Binding ◽  
Conformational Changes ◽  
Binding Domain ◽  
Host Cells ◽  
Spike Protein ◽  
Binding Affinities ◽  
Receptor Binding Domain ◽  
Rapid Spread ◽  
Related Proteins

The rapid spread of new SARS-CoV-2 variants needs the development of rapid tools for predicting the affinity of the mutated proteins responsible for the infection, i.e., the SARS-CoV-2 spike protein, for the human ACE2 receptor, aiming to understand if a variant can be more efficient in invading host cells. Here we show how our computational pipeline, previously used for studying SARS-CoV-2 spike receptor-binding domain (RBD)/ACE2 interactions and pre-/post-fusion conformational changes, can be used for predicting binding affinities of the human ACE2 receptor for the spike protein RBD of the characterized infectious variants of concern/interest B.1.1.7-UK (carrying the mutations N501Y, S494P, E484K at the RBD), P.1-Japan/Brazil (RBD mutations: K417N/T, E484K, N501Y), B.1.351-South Africa (RBD mutations: K417N, E484K, N501Y), B.1.427/B.1.429-California (RBD mutations: L452R), the B.1.141 variant (RBD mutations: N439K), and the recent B.1.617.1-India (RBD mutations: L452R; E484Q) and the B.1.620 (RBD mutations: S477N; E484K). Furthermore, we searched for ACE2 structurally related proteins that might be involved in interactions with the SARS-CoV-2 spike protein, in those tissues showing low ACE2 expression, revealing two new proteins, THOP1 and NLN, deserving to be investigated for their possible inclusion in the group of host-cell entry factors responsible for host-cell SARS-CoV-2 invasion and immunity response.

Antiviral Drug Design Based on the Opening Mechanism of Spike Glycoprotein in SARS-CoV-2

2021 ◽  
Author(s):  
Ruichao Mao ◽  
Lihua Bie ◽  
Maofeng Xu ◽  
Xiaocong Wang ◽  
Jun Gao
Keyword(s):  
Severe Acute Respiratory Syndrome ◽  
Drug Design ◽  
Host Cell ◽  
Receptor Binding ◽  
Antiviral Drug ◽  
Binding Domain ◽  
The Novel ◽  
Receptor Binding Domain ◽  
Spike Glycoprotein

The novel severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) enters the host cell after the receptor binding domain (RBD) of the virus spike (S) glycoprotein binding to the human angiotensin-converting...

scholarly journals The Tetherin Antagonism of the Ebola Virus Glycoprotein Requires an Intact Receptor-Binding Domain and Can Be Blocked by GP1-Specific Antibodies

2016 ◽  
Vol 90 (24) ◽  
pp. 11075-11086 ◽  
Author(s):  
Constantin Brinkmann ◽  
Inga Nehlmeier ◽  
Kerstin Walendy-Gnirß ◽  
Julia Nehls ◽  
Mariana González Hernández ◽  
...  
Keyword(s):  
Receptor Binding ◽  
Ebola Virus ◽  
Virus Disease ◽  
Human Cells ◽  
Binding Domain ◽  
Cell Protein ◽  
Target Cells ◽  
Receptor Binding Domain ◽  
Northern Spain ◽  
Tetherin Antagonism

ABSTRACT The glycoprotein of Ebola virus (EBOV GP), a member of the family Filoviridae , facilitates viral entry into target cells. In addition, EBOV GP antagonizes the antiviral activity of the host cell protein tetherin, which may otherwise restrict EBOV release from infected cells. However, it is unclear how EBOV GP antagonizes tetherin, and it is unknown whether the GP of Lloviu virus (LLOV), a filovirus found in dead bats in Northern Spain, also counteracts tetherin. Here, we show that LLOV GP antagonizes tetherin, indicating that tetherin may not impede LLOV spread in human cells. Moreover, we demonstrate that appropriate processing of N-glycans in tetherin/GP-coexpressing cells is required for tetherin counteraction by EBOV GP. Furthermore, we show that an intact receptor-binding domain (RBD) in the GP1 subunit of EBOV GP is a prerequisite for tetherin counteraction. In contrast, blockade of Niemann-Pick disease type C1 (NPC1), a cellular binding partner of the RBD, did not interfere with tetherin antagonism. Finally, we provide evidence that an antibody directed against GP1, which protects mice from a lethal EBOV challenge, may block GP-dependent tetherin antagonism. Our data, in conjunction with previous reports, indicate that tetherin antagonism is conserved among the GPs of all known filoviruses and demonstrate that the GP1 subunit of EBOV GP plays a central role in tetherin antagonism. IMPORTANCE Filoviruses are reemerging pathogens that constitute a public health threat. Understanding how Ebola virus (EBOV), a highly pathogenic filovirus responsible for the 2013-2016 Ebola virus disease epidemic in western Africa, counteracts antiviral effectors of the innate immune system might help to define novel targets for antiviral intervention. Similarly, determining whether Lloviu virus (LLOV), a filovirus detected in bats in northern Spain, is inhibited by innate antiviral effectors in human cells might help to determine whether the virus constitutes a threat to humans. The present study shows that LLOV, like EBOV, counteracts the antiviral effector protein tetherin via its glycoprotein (GP), suggesting that tetherin does not pose a defense against LLOV spread in humans. Moreover, our work identifies the GP1 subunit of EBOV GP, in particular an intact receptor-binding domain, as critical for tetherin counteraction and provides evidence that antibodies directed against GP1 can interfere with tetherin counteraction.

scholarly journals Monoclonal Antibody 667 Recognizes the Variable Region A Motif of the Ecotropic Retrovirus CasBrE Envelope Glycoprotein and Inhibits Env Binding to the Viral Receptor

2003 ◽  
Vol 77 (20) ◽  
pp. 10984-10993 ◽  
Author(s):  
Hanna Dreja ◽  
Laurent Gros ◽  
Sylvie Villard ◽  
Estanislao Bachrach ◽  
Anna Oates ◽  
...  
Keyword(s):  
Amino Acids ◽  
Monoclonal Antibody ◽  
Receptor Binding ◽  
Envelope Glycoprotein ◽  
Critical Role ◽  
Variable Region ◽  
Binding Domain ◽  
Target Cells ◽  
Kinetic Properties ◽  
Receptor Binding Domain

ABSTRACT Monoclonal antibody (MAb) 667 is a neutralizing mouse monoclonal antibody recognizing the envelope glycoprotein (Env) of the ecotropic neurotropic murine retrovirus CasBrE but not that of other murine retroviruses. Since 667 can be used for preclinical studies of antiviral gene therapy as well as for studying the early events of retroviral infection, we have cloned its cDNAs and molecularly characterized it in detail. Spot technique-based experiments showed that 667 recognizes a linear epitope of 12 amino acids located in the variable region A of the receptor binding domain. Alanine scanning experiments showed that six amino acids within the epitope are critical for MAb binding. One of them, D57, is not present in any other murine retroviral Env, which suggests a critical role for this residue in the selectivity of 667. MAb 667 heavy- and light-chain cDNAs were functionally characterized by transient transfection into Cos-7 cells. Enzyme-linked immunosorbent assays and Biacore studies showed that the specificities as well as the antigen-binding thermodynamic and kinetic properties of the recombinant 667 MAb (r667) produced by Cos-7 cells and those of the parental hybridoma-produced MAb (h667) were similar. However, h667 was shown to contain contaminating retroviral and/or retrovirus-like particles which interfere with both viral binding and neutralization experiments. These contaminants could successfully be removed by a stringent purification protocol. Importantly, this purified 667 could completely prevent retrovirus binding to target cells and was as efficient as the r667 MAb produced by transfected Cos-7 cells in neutralization assays. In conclusion, this study shows that the primary mechanism of virus neutralization by MAb 667 is the blocking of the retroviral receptor binding domain of CasBrE Env. In addition, the findings of this study constitute a warning against the direct use of hybridoma cell culture supernatants for studying the initial events of retroviral cell infection as well as for carrying out in vivo neutralization experiments and suggest that either recombinant antibodies or highly purified antibodies are preferable for these purposes.

scholarly journals Reovirus σ1 conformational flexibility modulates the efficiency of host cell attachment

2020 ◽  
Author(s):  
Julia R. Diller ◽  
Sean R. Halloran ◽  
Melanie Koehler ◽  
Rita dos Santos Natividade ◽  
David Alsteens ◽  
...  
Keyword(s):  
Host Cell ◽  
Receptor Binding ◽  
Cell Attachment ◽  
Conformational Flexibility ◽  
Binding Domain ◽  
Parental Virus ◽  
Receptor Binding Domain ◽  
Attachment Protein ◽  
Host Cell Attachment ◽  
Conformational Rearrangements

ABSTRACTReovirus attachment protein σ1 is a trimeric molecule containing tail, body, and head domains. During infection, σ1 engages sialylated glycans and junctional adhesion molecule-A (JAM-A), triggering uptake into the endocytic compartment, where virions are proteolytically converted to infectious subvirion particles (ISVPs). Further disassembly allows σ1 release and escape of transcriptionally active reovirus cores into the cytosol. Electron microscopy has revealed a distinct conformational change in σ1 from a compact form on virions to an extended form on ISVPs. To determine the importance of σ1 conformational mobility, we used reverse genetics to introduce cysteine mutations that can crosslink σ1 by establishing disulfide bonds between structurally adjacent sites in the tail, body, and head domains. We detected phenotypic differences among the engineered viruses. A mutant with a cysteine pair in the head domain replicates with enhanced kinetics, forms large plaques, and displays increased avidity for JAM-A relative to the parental virus, mimicking properties of ISVPs. However, unlike ISVPs, particles containing cysteine mutations that crosslink the head domain uncoat and transcribe viral positive-sense RNA with kinetics similar to the parental virus and are sensitive to ammonium chloride. Together, these data suggest that σ1 conformational flexibility modulates the efficiency of reovirus host cell attachment.IMPORTANCENonenveloped virus entry is an incompletely understood process. For reovirus, the functional significance of conformational rearrangements in the attachment protein, σ1, that occur during entry and particle uncoating are unknown. We engineered and characterized reoviruses containing cysteine mutations that crosslink σ1 monomers in non-reducing conditions. We found that the introduction of a cysteine pair in the receptor-binding domain of σ1 yielded a virus that replicates with faster kinetics than the parental virus and forms larger plaques. Using functional assays, we found that crosslinking the σ1 receptor-binding domain modulates reovirus attachment but not uncoating or transcription. These data suggest that σ1 conformational rearrangements mediate the efficiency of reovirus host cell attachment.

scholarly journals Molecular Docking study of Receptor Binding Domain of SARS-CoV-2 Spike Glycoprotein with Saikosaponin, a Triterpenoid Natural Product

2020 ◽  
Author(s):  
Tamal Goswami ◽  
Bhaskar Bagchi
Keyword(s):  
Molecular Docking ◽  
Receptor Binding ◽  
Docking Study ◽  
Binding Domain ◽  
Target Cells ◽  
Receptor Binding Domain ◽  
Spike Glycoprotein ◽  
Molecular Docking Study ◽  
Computational Docking ◽  
Angiotensin Converting Enzyme 2

The appearance of SARS-CoV-2 has resulted ~19000 deaths and ~423000 infections worldwide as of March 24, 2020. Coronavirus spike (S) glycoproteins hooks on target cells and binds to the angiotensin-converting enzyme 2 (ACE2) receptor. Recent researches speculated that residues 331 to 524 of the S glycoprotein of the receptor binding domain (RDB) of the spike is the most crucial target and this side was very important for computational docking. In the present study we have considered a series of saikosaponins and molecular docking was performed. Most of the docked molecules bind favorably to the RDB region of the spike glycoprotein and among them Saikosaponin B4 is the best inhibitor.

scholarly journals Differences and similarities between SARS-CoV and SARS-CoV-2: spike receptor-binding domain recognition and host cell infection with support of cellular serine proteases

Infection ◽  
2020 ◽  
Vol 48 (5) ◽  
pp. 665-669
Author(s):  
Giovanni A. Rossi ◽  
Oliviero Sacco ◽  
Enrica Mancino ◽  
Luca Cristiani ◽  
Fabio Midulla
Keyword(s):  
Host Cell ◽  
Receptor Binding ◽  
Serine Proteases ◽  
Immune Surveillance ◽  
Neutralizing Antibody ◽  
Binding Domain ◽  
Receptor Binding Domain ◽  
Cell Infection ◽  
Current State ◽  
Protease Activation

Abstract Novel severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) became pandemic by the end of March 2020. In contrast to the 2002–2003 SARS-CoV outbreak, which had a higher pathogenicity and lead to higher mortality rates, SARSCoV-2 infection appears to be much more contagious. Moreover, many SARS-CoV-2 infected patients are reported to develop low-titer neutralizing antibody and usually suffer prolonged illness, suggesting a more effective SARS-CoV-2 immune surveillance evasion than SARS-CoV. This paper summarizes the current state of art about the differences and similarities between the pathogenesis of the two coronaviruses, focusing on receptor binding domain, host cell entry and protease activation. Such differences may provide insight into possible intervention strategies to fight the pandemic.

scholarly journals Cloning, Expression and Biophysical Characterization of a Yeast-expressed Recombinant SARS-CoV-2 Receptor Binding Domain COVID-19 Vaccine Candidate

2020 ◽  
Author(s):  
Wen-Hsiang Chen ◽  
Junfei Wei ◽  
Rakhi Tyagi Kundu ◽  
Rakesh Adhikari ◽  
Zhuyun Liu ◽  
...  
Keyword(s):  
Receptor Binding ◽  
Structural Changes ◽  
Tertiary Structure ◽  
Vaccine Development ◽  
Glycosylation Site ◽  
Binding Domain ◽  
Effective Vaccine ◽  
Receptor Binding Domain ◽  
Biophysical Characterization ◽  
Recombinant Receptor

ABSTRACTCoronavirus disease 2019 (COVID-19) caused by SARS-CoV-2 has now spread worldwide to infect approximately 50 million people, with over 1 million reported deaths, and a safe and effective vaccine remains urgently needed. Based on previous experience developing vaccines against SARS and MERS, we constructed three variants of the recombinant receptor-binding domain (RBD) of the SARS-CoV-2 spike (S) protein (residues 331-549) in yeast as follows: (1) a “wild type” RBD (RBD219-WT), (2) a deglycosylated form (RBD219-N1) by deleting the first N-glycosylation site, and (3) a combined deglycosylated and cysteine (C538A-mutated variant (RBD219-N1C1)). We compared the expression yields, biophysical characteristics, and functionality of the proteins produced from these constructs. Collectively, these three recombinant protein RBDs showed similar secondary and tertiary structure thermal stability and had the same affinity for their receptor, angiotensin-converting enzyme 2 (ACE-2), suggesting that the selected deletion or mutations did not cause any significant structural changes or alteration of function. However, RBD219-N1C1 had a higher fermentation yield, was easier to purify, and had a lower tendency to form oligomers when compared to the other two proteins and was therefore selected for further vaccine development and evaluation.

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