Kinetics of HCV envelope proteins’ interaction with CD81 large extracellular loop

2005 ◽  
Vol 328 (4) ◽  
pp. 1091-1100 ◽  
Author(s):  
Hideki Nakajima ◽  
Laurence Cocquerel ◽  
Nobutaka Kiyokawa ◽  
Junichiro Fujimoto ◽  
Shoshana Levy
Keyword(s):  
Envelope Proteins ◽  
Extracellular Loop ◽  
Large Extracellular Loop ◽  
Kinetics Of

scholarly journals Large Extracellular Loop of Tetraspanin as a Potential Vaccine Candidate for Filariasis

PLoS ONE ◽  
2013 ◽  
Vol 8 (10) ◽  
pp. e77394 ◽  
Author(s):  
Gajalakshmi Dakshinamoorthy ◽  
Gnanasekar Munirathinam ◽  
Kristen Stoicescu ◽  
Maryada Venkatarami Reddy ◽  
Ramaswamy Kalyanasundaram
Keyword(s):  
Vaccine Candidate ◽  
Extracellular Loop ◽  
Potential Vaccine Candidate ◽  
Large Extracellular Loop ◽  
Potential Vaccine

scholarly journals A Novel gp41-Binding Adnectin with Potent Anti-HIV Activity Is Highly Synergistic when Linked to a CD4-Binding Adnectin

2018 ◽  
Vol 92 (14) ◽  
Author(s):  
David Wensel ◽  
Yongnian Sun ◽  
Jonathan Davis ◽  
Zhufang Li ◽  
Sharon Zhang ◽  
...  
Keyword(s):  
Envelope Proteins ◽  
Coding Region ◽  
Intrinsic Resistance ◽  
Target Region ◽  
Medical Needs ◽  
Spectrum Activity ◽  
Conserved Region ◽  
Long Acting ◽  
Kinetics Of ◽  
Hiv 1

ABSTRACTThe N17 region of gp41 in HIV-1 is the most conserved region in gp160. mRNA selection technologies were used to identify an adnectin that binds to this region and inhibits gp41-induced membrane fusion. Additional selection conditions were used to optimize the adnectin to greater potency (5.4 ± 2.6 nM) against HIV-1 and improved binding affinity for an N17-containing helical trimer (0.8 ± 0.4 nM). Resistance to this adnectin mapped to a single Glu-to-Arg change within the N17 coding region. The optimized adnectin (6200_A08) exhibited high potency and broad-spectrum activity against 123 envelope proteins and multiple clinical virus isolates, although certain envelope proteins did exhibit reduced susceptibility to 6200_A08 alone. The reduced potency could not be correlated with sequence changes in the target region and was thought to be the result of faster kinetics of fusion mediated by these envelope proteins. Optimized linkage of 6200_A08 with a previously characterized adnectin targeting CD4 produced a highly synergistic molecule, with the potency of the tandem molecule measured at 37 ± 1 pM. In addition, these tandem molecules now exhibited few potency differences against the same panel of envelope proteins with reduced susceptibility to 6200_A08 alone, providing evidence that they did not have intrinsic resistance to 6200_A08 and that coupling 6200_A08 with the anti-CD4 adnectin may provide a higher effective on rate for gp41 target engagement.IMPORTANCEThere continue to be significant unmet medical needs for patients with HIV-1 infection. One way to improve adherence and decrease the likelihood of drug-drug interactions in HIV-1-infected patients is through the development of long-acting biologic inhibitors. This study describes the development and properties of an adnectin molecule that targets the most conserved region of the gp41 protein and inhibits HIV-1 with good potency. Moreover, when fused to a similar adnectin targeted to the human CD4 protein, the receptor for HIV-1, significant synergies in potency and efficacy are observed. These inhibitors are part of an effort to develop a larger biologic molecule that functions as a long-acting self-administered regimen for patients with HIV-1 infection.

scholarly journals The Large Extracellular Loop of CD63 Interacts with gp41 of HIV-1 and is Essential for Establishing the Virological Synapse

2020 ◽  
Author(s):  
Daniel Ivanusic ◽  
Kazimierz Madela ◽  
Norbert Bannert ◽  
Joachim Denner
Keyword(s):  
Molecular Mechanisms ◽  
Core Protein ◽  
Biological Significance ◽  
Virological Synapse ◽  
Extracellular Loop ◽  
Protein Gp41 ◽  
Large Extracellular Loop ◽  
Cell Spread ◽  
Hiv 1 ◽  
Cell Cell

Abstract Human immunodeficiency virus type 1 (HIV-1) persists lifelong in infected individuals and has evolved unique strategies in order to evade the immune system. One of these strategies is the direct cell-to-cell spread of HIV-1. The formation of a virological synapse (VS) between donor and target cell is important for this process. Tetraspanins are cellular proteins that are actively involved in the formation of a VS. However, the molecular mechanisms of recruiting host proteins for the cell-cell transfer of particles to the VS remains unclear. Our study has mapped the binding site for the transmembrane envelope protein gp41 of HIV-1 within the large extracellular loop (LEL) of CD63 and showed that this interaction occurs predominantly at the VS between T cells where viral particles are transferred. Mutations within the highly conserved CCG motif of the tetraspanin superfamily abrogated recruiting of expressed HIV-1 GFP fused Gag core protein and CD63 to the VS. This demonstrates the biological significance of CD63 for enhanced formation of a VS. Since cell-cell spread of HIV-1 is a major route of persistent infection, these results highlight the central role of CD63 as a member of the tetraspanin superfamily during HIV-1 infection and pathogenesis.

scholarly journals Identification of the Hepatitis C Virus E2 Glycoprotein Binding Site on the Large Extracellular Loop of CD81

2002 ◽  
Vol 76 (21) ◽  
pp. 11143-11147 ◽  
Author(s):  
Heidi E. Drummer ◽  
Kirilee A. Wilson ◽  
Pantelis Poumbourios
Keyword(s):  
Hepatitis C Virus ◽  
Hepatitis C ◽  
Binding Site ◽  
Nk Cell ◽  
Cell Activity ◽  
Random Mutagenesis ◽  
Extracellular Loop ◽  
Human T Cell ◽  
Large Extracellular Loop

ABSTRACT The binding of hepatitis C virus glycoprotein E2 to the large extracellular loop (LEL) of CD81 has been shown to modulate human T-cell and NK cell activity in vitro. Using random mutagenesis of a chimera of maltose-binding protein and LEL residues 113 to 201, we have determined that the E2-binding site on CD81 comprises residues Ile182, Phe186, Asn184, and Leu162. These findings reveal an E2-binding surface of approximately 806 Å2 and potential target sites for the development of small-molecule inhibitors of E2 binding.

Subunit Association and Conformational Flexibility in the Head Subdomain of Human CD81 Large Extracellular Loop

2002 ◽  
Vol 383 (9) ◽  
Author(s):  
K. Kitadokoro ◽  
M. Ponassi ◽  
G. Galli ◽  
R. Petracca ◽  
F. Falugi ◽  
...  
Keyword(s):  
Conformational Flexibility ◽  
Extracellular Loop ◽  
Large Extracellular Loop

cDNA cloning of a novel G protein-coupled receptor with a large extracellular loop structure

1996 ◽  
Vol 1305 (1-2) ◽  
pp. 39-43 ◽  
Author(s):  
Aleksandra Roglić ◽  
Eric R. Prossnitz ◽  
Stacey L. Cavanagh ◽  
Zhixing Pan ◽  
Aihua Zou ◽  
...  
Keyword(s):  
G Protein ◽  
Cdna Cloning ◽  
Loop Structure ◽  
Extracellular Loop ◽  
G Protein Coupled Receptor ◽  
Large Extracellular Loop ◽  
G Protein Coupled

scholarly journals Structural Basis of Ligand Interactions of the Large Extracellular Domain of Tetraspanin CD81

2012 ◽  
Vol 86 (18) ◽  
pp. 9606-9616 ◽  
Author(s):  
Sundaresan Rajesh ◽  
Pooja Sridhar ◽  
Birke Andrea Tews ◽  
Lucie Fénéant ◽  
Laurence Cocquerel ◽  
...  
Keyword(s):  
Mammalian Cells ◽  
Primary Liver Cancer ◽  
Structural Basis ◽  
Extracellular Loop ◽  
Entry Level ◽  
Interaction Sites ◽  
Loop Region ◽  
Binding Interface ◽  
Ligand Interactions ◽  
Large Extracellular Loop

Hepatitis C virus (HCV) causes chronic liver disease, cirrhosis, and primary liver cancer. Despite 130 million people being at risk worldwide, no vaccine exists, and effective therapy is limited by drug resistance, toxicity, and high costs. The tetraspanin CD81 is an essential entry-level receptor required for HCV infection of hepatocytes and represents a critical target for intervention. In this study, we report the first structural characterization of the large extracellular loop of CD81, expressed in mammalian cells and studied in physiological solutions. The HCV E2 glycoprotein recognizes CD81 through a dynamic loop on the helical bundle, which was shown by nuclear magnetic resonance (NMR) spectroscopy to adopt a conformation distinct from that seen in crystals. A novel membrane binding interface was revealed adjacent to the exposed HCV interaction site in the extracellular loop of CD81. The binding pockets for two proposed inhibitors of the CD81-HCV interaction, namely, benzyl salicylate and fexofenadine, were shown to overlap the HCV and membrane interaction sites. Although the dynamic loop region targeted by these compounds presents challenges for structure-based design, the NMR assignments enable realistic screening and validation of ligands. Together, these data provide an improved avenue for developing potent agents that specifically block CD81-HCV interaction and also pave a way for elucidating the recognition mechanisms of diverse tetraspanins.

scholarly journals Stabilization of the CD81 Large Extracellular Loop with De Novo Disulfide Bonds Improves Its Amenability for Peptide Grafting

Pharmaceutics ◽  
2018 ◽  
Vol 10 (3) ◽  
pp. 138 ◽  
Author(s):  
Stefan Vogt ◽  
Gerhard Stadlmayr ◽  
Katharina Stadlbauer ◽  
Flávio Sádio ◽  
Peter Andorfer ◽  
...  
Keyword(s):  
Disulfide Bonds ◽  
De Novo ◽  
Specific Antigen ◽  
Thermal Stabilization ◽  
Peptide Sequence ◽  
Size Exclusion ◽  
Extracellular Loop ◽  
Human Transferrin Receptor ◽  
Exclusion Chromatography ◽  
Large Extracellular Loop

Tetraspan proteins are significantly enriched in the membranes of exosomal vesicles (EVs) and their extracellular domains are attractive targets for engineering towards specific antigen recognition units. To enhance the tolerance of a tetraspanin fold to modification, we achieved significant thermal stabilization of the human CD81 large extracellular loop (hCD81 LEL) via de novo disulfide bonds. The best mutants were shown to exhibit a positive shift in the melting temperature (Tm) of up to 25 °C. The combination of two most potent disulfide bonds connecting different strands of the protein resulted in a mutant with a Tm of 109 °C, 43 °C over the Tm of the wild-type hCD81 LEL. A peptide sequence binding to the human transferrin receptor (hTfr) was engrafted into the D-segment of the hCD81 LEL, resulting in a mutant that still exhibited a compact fold. Grafting of the same peptide sequence between helices A and B resulted in a molecule with an aberrant profile in size exclusion chromatography (SEC), which could be improved by a de novo cysteine bond connecting both helices. Both peptide-grafted proteins showed an enhanced internalization into the cell line SK-BR3, which strongly overexpresses hTfr. In summary, the tetraspan LEL fold could be stabilized to enhance its amenability for engineering into a more versatile protein scaffold.

Protein-dynamics of the putative HCV receptor CD81 large extracellular loop

2004 ◽  
Vol 14 (7) ◽  
pp. 1765-1769 ◽  
Author(s):  
Alexander Neugebauer ◽  
Christian D.P. Klein ◽  
Rolf W. Hartmann
Keyword(s):  
Protein Dynamics ◽  
Extracellular Loop ◽  
Large Extracellular Loop
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