scholarly journals Structural investigation of ACE2 dependent disassembly of the trimeric SARS-CoV-2 Spike glycoprotein

2020 ◽  
Author(s):  
Dongchun Ni ◽  
Kelvin Lau ◽  
Frank Lehmann ◽  
Andri Fränkl ◽  
David Hacker ◽  
...  
Keyword(s):  
Structural Rearrangement ◽  
Host Cells ◽  
Surface Glycoprotein ◽  
Angiotensin Converting Enzyme 2 ◽  
Cryo Electron Microscopy ◽  
Monomeric Complex ◽  
Electron Microscopy Analysis ◽  
Microscopy Analysis ◽  
Viral Surface

AbstractThe human membrane protein Angiotensin-converting enzyme 2 (hACE2) acts as the main receptor for host cells invasion of the new coronavirus SARS-CoV-2. The viral surface glycoprotein Spike binds to hACE2, which triggers virus entry into cells. As of today, the role of hACE2 for virus fusion is not well understood. Blocking the transition of Spike from its prefusion to post-fusion state might be a strategy to prevent or treat COVID-19. Here we report a single particle cryo-electron microscopy analysis of SARS-CoV-2 trimeric Spike in presence of the human ACE2 ectodomain. The binding of purified hACE2 ectodomain to Spike induces the disassembly of the trimeric form of Spike and a structural rearrangement of its S1 domain to form a stable, monomeric complex with hACE2. This observed hACE2 dependent dissociation of the Spike trimer suggests a mechanism for the therapeutic role of recombinant soluble hACE2 for treatment of COVID-19.

scholarly journals Antiparasitic Properties of Cardiovascular Agents against Human Intravascular Parasite Schistosoma mansoni

2021 ◽  
Vol 14 (7) ◽  
pp. 686
Author(s):  
Raquel Porto ◽  
Ana C. Mengarda ◽  
Rayssa A. Cajas ◽  
Maria C. Salvadori ◽  
Fernanda S. Teixeira ◽  
...  
Keyword(s):  
Schistosoma Mansoni ◽  
Screening Strategy ◽  
Early Infection ◽  
Global Public Health ◽  
Parasitic Worm ◽  
Electron Microscopy Analysis ◽  
Health Significance ◽  
Microscopy Analysis

The intravascular parasitic worm Schistosoma mansoni is a causative agent of schistosomiasis, a disease of great global public health significance. Praziquantel is the only drug available to treat schistosomiasis and there is an urgent demand for new anthelmintic agents. Adopting a phenotypic drug screening strategy, here, we evaluated the antiparasitic properties of 46 commercially available cardiovascular drugs against S. mansoni. From these screenings, we found that amiodarone, telmisartan, propafenone, methyldopa, and doxazosin affected the viability of schistosomes in vitro, with effective concentrations of 50% (EC50) and 90% (EC90) values ranging from 8 to 50 µM. These results were further supported by scanning electron microscopy analysis. Subsequently, the most effective drug (amiodarone) was further tested in a murine model of schistosomiasis for both early and chronic S. mansoni infections using a single oral dose of 400 mg/kg or 100 mg/kg daily for five consecutive days. Amiodarone had a low efficacy in chronic infection, with the worm and egg burden reduction ranging from 10 to 30%. In contrast, amiodarone caused a significant reduction in worm and egg burden in early infection (>50%). Comparatively, treatment with amiodarone is more effective in early infection than praziquantel, demonstrating the potential role of this cardiovascular drug as an antischistosomal agent.

scholarly journals Isolation of Disease-relevant p53 for Cryo-Electron Microscopy Analysis

2021 ◽  
Author(s):  
Maria J. Solares ◽  
GM Jonaid ◽  
William Y. Luqiu ◽  
Yanping Liang ◽  
Madison C. Evans ◽  
...  
Keyword(s):  
P53 Protein ◽  
P53 Gene ◽  
Tp53 Gene ◽  
Tumor Suppressor Protein ◽  
Protein Assemblies ◽  
Cryo Electron Microscopy ◽  
Naturally Occurring ◽  
Imaging Protocols ◽  
Electron Microscopy Analysis ◽  
Microscopy Analysis

Abstract Tumor suppressor protein TP53 (p53) plays a multi-faceted role in all cells of thehuman body. Sadly, mutations in the TP53 gene are involved in nearly ~50% of tumors,spurring erratic cell growth and disease progression. Until recently, structural informationfor p53 remained incomplete and there are limited studies on native p53 produced inhuman tumors. Here, we present a highly reproducible and effective protocol to extract,enrich, and purify native p53 protein assemblies from cancer cells for downstreamstructural studies. This method does not introduce purification tags into the p53 gene andmaintains naturally occurring modifications. In conjunction with cryo-Electron Microscopytechniques, we determined new structures for p53 monomers (~50 kDa) and tetramers(~200 kDa) at spatial resolutions of ~4.8 Å and ~7 Å, respectively.1 These modelsrevealed new insights for flexible regions of p53 along with biologically-relevantubiquitination sites. Combining biochemical and structural imaging protocols, we aim tobuild a better understanding of native p53’s impact in cancer formation.

scholarly journals Evolution of infectious bronchitis virus in the field after homologous vaccination introduction

2019 ◽  
Vol 50 (1) ◽  
Author(s):  
Giovanni Franzo ◽  
Matteo Legnardi ◽  
Claudia Maria Tucciarone ◽  
Michele Drigo ◽  
Marco Martini ◽  
...  
Keyword(s):  
Infectious Bronchitis Virus ◽  
Viral Evolution ◽  
Surface Glycoprotein ◽  
Rna Sequences ◽  
Viral Attachment ◽  
Infectious Bronchitis ◽  
Before And After ◽  
Viral Surface ◽  
Induced Immunity

Abstract Despite the fact that vaccine resistance has been typically considered a rare phenomenon, some episodes of vaccine failure have been reported with increasing frequency in intensively-raised livestock. Infectious bronchitis virus (IBV) is a widespread avian coronavirus, whose control relies mainly on extensive vaccine administration. Unfortunately, the continuous emergence of new vaccine-immunity escaping variants prompts the development of new vaccines. In the present work, a molecular epidemiology study was performed to evaluate the potential role of homologous vaccination in driving IBV evolution. This was undertaken by assessing IBV viral RNA sequences from the ORF encoding the S1 portion of viral surface glycoprotein (S) before and after the introduction of a new live vaccine on broiler farms in northern-Italy. The results of several biostatistics analyses consistently demonstrate the presence of a higher pressure in the post-vaccination period. Natural selection was detected essentially on sites located on the protein surface, within or nearby domains involved in viral attachment or related functions. This evidence strongly supports the action of vaccine-induced immunity in conditioning viral evolution, potentially leading to the emergence of new vaccine-escape variants. The great plasticity of rapidly-evolving RNA-viruses in response to human intervention, which extends beyond the poultry industry, is demonstrated, claiming further attention due to their relevance for animal and especially human health.

scholarly journals Body Localization of ACE-2: On the Trail of the Keyhole of SARS-CoV-2

2020 ◽  
Vol 7 ◽  
Author(s):  
Francesca Salamanna ◽  
Melania Maglio ◽  
Maria Paola Landini ◽  
Milena Fini
Keyword(s):  
Multiple Organ ◽  
Host Cells ◽  
Specific Patient ◽  
Angiotensin Converting Enzyme 2 ◽  
Body Distribution ◽  
Organ Failures ◽  
Personalized Approach ◽  
Potential Interactions

The explosion of the new coronavirus (SARS-CoV-2) pandemic has brought the role of the angiotensin converting enzyme 2 (ACE2) back into the scientific limelight. Since SARS-CoV-2 must bind the ACE2 for entering the host cells in humans, its expression and body localization are critical to track the potential target organ of this infection and to outline disease progression and clinical outcomes. Here, we mapped the physiological body distribution, expression, and activities of ACE2 and discussed its potential correlations and mutal interactions with the disparate symptoms present in SARS-CoV-2 patients at the level of different organs. We highlighted that despite during SARS-CoV-2 infection ACE2-expressing organs may become direct targets, leading to severe pathological manifestations, and subsequent multiple organ failures, the exact mechanism and the potential interactions through which ACE2 acts in these organs is still heavily debated. Further scientific efforts, also considering a personalized approach aimed to consider specific patient differences in the mutual interactions ACE2-SARS-CoV-2 and the long-term health effects associated with COVID-19 are currently mandatory.

scholarly journals Insight into structural diversity of influenza virus haemagglutinin

2013 ◽  
Vol 94 (8) ◽  
pp. 1712-1722 ◽  
Author(s):  
Ki Joon Cho ◽  
Ji-Hye Lee ◽  
Kwang W. Hong ◽  
Se-Ho Kim ◽  
Yiho Park ◽  
...  
Keyword(s):  
Influenza Virus ◽  
Complex Structure ◽  
Structural Diversity ◽  
Biochemical Properties ◽  
Host Cells ◽  
Surface Glycoprotein ◽  
Lower Protein ◽  
Viral Surface ◽  
Influenza Virus Haemagglutinin ◽  
Increased Susceptibility

Influenza virus infects host cells through membrane fusion, a process mediated by the low pH-induced conformational change of the viral surface glycoprotein haemagglutinin (HA). We determined the structures and biochemical properties of the HA proteins from A/Korea/01/2009 (KR01), a 2009 pandemic strain, and A/Thailand/CU44/2006 (CU44), a seasonal strain. The crystal structure of KR01 HA revealed a V-shaped head-to-head arrangement, which is not seen in other HA proteins including CU44 HA. We isolated a broadly neutralizing H1-specific monoclonal antibody GC0757. The KR01 HA-Fab0757 complex structure also exhibited a head-to-head arrangement of HA. Both native and Fab complex structures reveal a different spatial orientation of HA1 relative to HA2, indicating that HA is flexible and dynamic at neutral pH. Further, the KR01 HA exhibited significantly lower protein stability and increased susceptibility to proteolytic cleavage compared with other HAs. Our structures provide important insights into the conformational flexibility of HA.

Production and characterization of titanium and iron oxide nano-sized thin films

2001 ◽  
Vol 16 (6) ◽  
pp. 1559-1564 ◽  
Author(s):  
E. Comini ◽  
G. Sberveglieri ◽  
M. Ferroni ◽  
V. Guidi ◽  
C. Frigeri ◽  
...  
Keyword(s):  
Thin Films ◽  
Iron Oxide ◽  
Gas Sensing ◽  
Iron Concentration ◽  
Radio Frequency Sputtering ◽  
Electron Microscopy Analysis ◽  
Microscopy Analysis ◽  
Reproducible Method

We present a simple and reproducible method to obtain TiO2 and Fe2O3 mixed-oxide thin films by reactive radio-frequency sputtering. The influence of iron concentration on the structural properties of the layers has been studied. Structural characterization, carried out by electron microscopy analysis, allowed one to correlate the inhibition of the grain growth of titania to the presence of iron oxide and to its segregation at grain boundaries. This behavior should be ascribed to a superficial-tension phenomenon. As a possible application of these thin films, we have investigated the gas-sensing properties toward CO, with particular focus on the role of Fe. The layers were capable to sense CO down to the level requested for environmental monitoring.

scholarly journals Structural basis of ER-associated protein degradation mediated by the Hrd1 ubiquitin ligase complex

Science ◽  
2020 ◽  
Vol 368 (6489) ◽  
pp. eaaz2449 ◽  
Author(s):  
Xudong Wu ◽  
Marc Siggel ◽  
Sergey Ovchinnikov ◽  
Wei Mi ◽  
Vladimir Svetlov ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Ubiquitin Ligase ◽  
Dynamics Simulation ◽  
Structural Basis ◽  
Cryo Electron Microscopy ◽  
Ubiquitin Ligase Complex ◽  
Electron Microscopy Analysis ◽  
Microscopy Analysis ◽  
Simulation Results ◽  
Membrane Region

Misfolded luminal endoplasmic reticulum (ER) proteins undergo ER-associated degradation (ERAD-L): They are retrotranslocated into the cytosol, polyubiquitinated, and degraded by the proteasome. ERAD-L is mediated by the Hrd1 complex (composed of Hrd1, Hrd3, Der1, Usa1, and Yos9), but the mechanism of retrotranslocation remains mysterious. Here, we report a structure of the active Hrd1 complex, as determined by cryo–electron microscopy analysis of two subcomplexes. Hrd3 and Yos9 jointly create a luminal binding site that recognizes glycosylated substrates. Hrd1 and the rhomboid-like Der1 protein form two “half-channels” with cytosolic and luminal cavities, respectively, and lateral gates facing one another in a thinned membrane region. These structures, along with crosslinking and molecular dynamics simulation results, suggest how a polypeptide loop of an ERAD-L substrate moves through the ER membrane.

scholarly journals Protein crowding mediates membrane remodeling in upstream ESCRT-induced formation of intraluminal vesicles

2020 ◽  
Vol 117 (46) ◽  
pp. 28614-28624
Author(s):  
Susanne Liese ◽  
Eva Maria Wenzel ◽  
Ingrid Kjos ◽  
Rossana Rojas Molina ◽  
Sebastian W. Schultz ◽  
...  
Keyword(s):  
Degradation Pathway ◽  
Bending Rigidity ◽  
Lysosomal Degradation ◽  
Endosomal Sorting ◽  
Electron Microscopy Analysis ◽  
Steep Decline ◽  
Microscopy Analysis ◽  
Protein Crowding ◽  
Membrane Shape

As part of the lysosomal degradation pathway, the endosomal sorting complexes required for transport (ESCRT-0 to -III/VPS4) sequester receptors at the endosome and simultaneously deform the membrane to generate intraluminal vesicles (ILVs). Whereas ESCRT-III/VPS4 have an established function in ILV formation, the role of upstream ESCRTs (0 to II) in membrane shape remodeling is not understood. Combining experimental measurements and electron microscopy analysis of ESCRT-III–depleted cells with a mathematical model, we show that upstream ESCRT-induced alteration of the Gaussian bending rigidity and their crowding in concert with the transmembrane cargo on the membrane induce membrane deformation and facilitate ILV formation: Upstream ESCRT-driven budding does not require ATP consumption as only a small energy barrier needs to be overcome. Our model predicts that ESCRTs do not become part of the ILV, but localize with a high density at the membrane neck, where the steep decline in the Gaussian curvature likely triggers ESCRT-III/VPS4 assembly to enable neck constriction and scission.

Sign in / Sign up

Export Citation Format

Share Document