Insight into structural diversity of influenza virus haemagglutinin

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.

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

10.1101/2020.10.12.336016 ◽

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.

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Polymorphisms in the haemagglutinin gene influenced the viral shedding of pandemic 2009 influenza virus in swine

Journal of General Virology ◽

10.1099/vir.0.067926-0 ◽

2014 ◽

Vol 95 (12) ◽

pp. 2618-2626 ◽

Cited By ~ 4

Author(s):

Alessio Lorusso ◽

Janice R. Ciacci-Zanella ◽

Eraldo L. Zanella ◽

Lindomar Pena ◽

Daniel R. Perez ◽

...

Keyword(s):

Influenza Virus ◽

Amino Acid ◽

Consensus Sequence ◽

Influenza Virus Infection ◽

Antigenic Site ◽

Cross Reactivity ◽

Influenza Viruses ◽

Host Cells ◽

Surface Glycoprotein ◽

Viral Shedding

Interactions between the viral surface glycoprotein haemagglutinin (HA) and the corresponding receptors on host cells is one important aspect of influenza virus infection. Mutations in HA have been described to affect pathogenicity, antigenicity and the transmission of influenza viruses. Here, we detected polymorphisms present in HA genes of two pandemic 2009 H1N1 (H1N1pdm09) isolates, A/California/04/2009 (Ca/09) and A/Mexico/4108/2009 (Mx/09), that resulted in amino acid changes at positions 186 (S to P) and 194 (L to I) of the mature HA1 protein. Although not reported in the published H1N1pdm09 consensus sequence, the P186 genotype was more readily detected in primary infected and contact-naïve pigs when inoculated with a heterogeneous mixed stock of Ca/09. Using reverse genetics, we engineered Ca/09 and Mx/09 genomes by introducing Ca/09 HA with two naturally occurring variants expressing S186/I194 (HA-S/I) and P186/L194 (HA-P/L), respectively. The Ca/09 HA with the combination of P186/L194 with either the Ca/09 or Mx/09 backbone resulted in higher and prolonged viral shedding in naïve pigs. This efficiency appeared to be more likely through an advantage in cell surface attachment rather than replication efficiency. Although these mutations occurred within the receptor-binding pocket and the Sb antigenic site, they did not affect serological cross-reactivity. Relative increases of P186 in publicly available sequences from swine H1N1pdm09 viruses supported the experimental data, indicating this amino acid substitution conferred an advantage in swine.

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ACIS, A Novel KepTide™, Binds to ACE-2 Receptor and Inhibits the Infection of SARS-CoV2 Virus in vitro in Primate Kidney Cells: Therapeutic Implications for COVID-19 (Preprint)

10.2196/preprints.25089 ◽

2020 ◽

Author(s):

Avik Sotira Scientific

Keyword(s):

Social Life ◽

Plaque Assay ◽

Host Cells ◽

Surface Glycoprotein ◽

Crystallographic Structure ◽

Therapeutic Implications ◽

Biochemical Assays ◽

Targeted Medicine

UNSTRUCTURED Coronavirus disease 2019 (COVID-19) is a severe acute respiratory syndrome (SARS) caused by a virus known as SARS-Coronavirus 2 (SARS-CoV2). Without a targeted-medicine, this disease has been causing a massive humanitarian crisis not only in terms of mortality, but also imposing a lasting damage to social life and economic progress of humankind. Therefore, an immediate therapeutic strategy needs to be intervened to mitigate this global crisis. Here, we report a novel KepTide™ (Knock-End Peptide) therapy that nullifies SARS-CoV2 infection. SARS-CoV2 employs its surface glycoprotein “spike” (S-glycoprotein) to interact with angiotensin converting enzyme-2 (ACE-2) receptor for its infection in host cells. Based on our in-silico-based homology modeling study validated with a recent X-ray crystallographic structure (PDB ID:6M0J), we have identified that a conserved motif of S-glycoprotein that intimately engages multiple hydrogen-bond (H-bond) interactions with ACE-2 enzyme. Accordingly, we designed a peptide, termed as ACIS (ACE-2 Inhibitory motif of Spike), that displayed significant affinity towards ACE-2 enzyme as confirmed by biochemical assays such as BLItz and fluorescence polarization assays. Interestingly, more than one biochemical modifications were adopted in ACIS in order to enhance the inhibitory action of ACIS and hence called as KEpTide™. Consequently, a monolayer invasion assay, plaque assay and dual immunofluorescence analysis further revealed that KEpTide™ efficiently mitigated the infection of SARS-CoV2 in vitro in VERO E6 cells. Finally, evaluating the relative abundance of ACIS in lungs and the potential side-effects in vivo in mice, our current study discovers a novel KepTide™ therapy that is safe, stable, and robust to attenuate the infection of SARS-CoV2 virus if administered intranasally. INTERNATIONAL REGISTERED REPORT RR2-https://doi.org/10.1101/2020.10.13.337584

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Targeting Viral Surface Proteins through Structure-Based Design

Viruses ◽

10.3390/v13071320 ◽

2021 ◽

Vol 13 (7) ◽

pp. 1320

Author(s):

Yogesh B Narkhede ◽

Karen J Gonzalez ◽

Eva-Maria Strauch

Keyword(s):

Public Health ◽

Viral Infections ◽

Respiratory Viruses ◽

Surface Proteins ◽

Host Cells ◽

Viral Fusion ◽

Health It ◽

Viral Particles ◽

Pathogenic Viruses ◽

Viral Surface

The emergence of novel viral infections of zoonotic origin and mutations of existing human pathogenic viruses represent a serious concern for public health. It warrants the establishment of better interventions and protective therapies to combat the virus and prevent its spread. Surface glycoproteins catalyzing the fusion of viral particles and host cells have proven to be an excellent target for antivirals as well as vaccines. This review focuses on recent advances for computational structure-based design of antivirals and vaccines targeting viral fusion machinery to control seasonal and emerging respiratory viruses.

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A Variable Region on the Chlorovirus CVK2 Genome Contains Five Copies of the Gene for Vp260, a Viral-Surface Glycoprotein

Virology ◽

10.1006/viro.2002.1408 ◽

2002 ◽

Vol 295 (2) ◽

pp. 289-298 ◽

Cited By ~ 10

Author(s):

Niti Chuchird ◽

Kensho Nishida ◽

Takeru Kawasaki ◽

Makoto Fujie ◽

Shoji Usami ◽

...

Keyword(s):

Variable Region ◽

Surface Glycoprotein ◽

Viral Surface

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The conformation of influenza virus haemagglutinin

FEBS Letters ◽

10.1016/0014-5793(77)80406-7 ◽

1977 ◽

Vol 80 (1) ◽

pp. 57-60 ◽

Cited By ~ 16

Author(s):

M.T. Flanagan ◽

J.J. Skehel

Keyword(s):

Influenza Virus ◽

Influenza Virus Haemagglutinin ◽

Virus Haemagglutinin

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The Use of Lectins as Tools to Combat SARS-CoV-2

Current Pharmaceutical Design ◽

10.2174/1381612827666210830094743 ◽

2021 ◽

Vol 27 ◽

Author(s):

Daniela Martinez ◽

Diego Amaral ◽

David Markovitz ◽

Luciano Pinto

Keyword(s):

Viral Infection ◽

Host Cells ◽

Viral Fusion ◽

Cell Receptors ◽

First Case ◽

Mannose Binding ◽

New Treatments ◽

Viral Surface

Background: in december 2019, china announced the first case of an infection caused by an, until then, unknown virus: sars-cov-2. since then, researchers have been looking for viable alternatives for the treatment and/or cure of viral infection. among the possible complementary solutions are lectins, and proteins that are reversibly bound to different carbohydrates. the spike protein, present on the viral surface, can interact with different cell receptors: ace2, cd147, and dc-signr. since lectins have an affinity for different carbohydrates, the binding with the glycosylated cell receptors represents a possibility of preventing the virus from binding to the receptors of host cells. Objective: in this review we discuss the main lectins that are possible candidates for use in the treatment of covid-19, highlighting those that have already demonstrated antiviral activity in vivo and in vitro, including mannose-binding lectin, griffithsin, banlec, and others. we also aim to discuss the possible mechanism of action of lectins, which appears to occur through the mediation of viral fusion in host cells, by binding of lectins to glycosylated receptors found in human cells and/or binding of these proteins with the spike glycoprotein, present in virus surface.moreover, we also discuss the use of lectins in clinical practice. Conclusion: Even with the development of effective vaccines, new cases of viral infection with the same virus, or new outbreaks with different viruses can occur; so, the development of new treatments should not be discarded. moreover, the discussions made in this work are relevant regarding the anti-viral properties of lectins.

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Methyl phenlactonoates are efficient strigolactone analogs with simple structure

Journal of Experimental Botany ◽

10.1093/jxb/erx438 ◽

2017 ◽

Vol 69 (9) ◽

pp. 2319-2331 ◽

Cited By ~ 14

Author(s):

Muhammad Jamil ◽

Boubacar A Kountche ◽

Imran Haider ◽

Xiujie Guo ◽

Valentine O Ntui ◽

...

Keyword(s):

Mycorrhizal Fungi ◽

Simple Structure ◽

Complex Structure ◽

Arbuscular Mycorrhizal ◽

Structural Diversity ◽

Striga Hermonthica ◽

Biological Processes ◽

Structural Modifications ◽

New Class ◽

Agricultural Applications

abstract Strigolactones (SLs) are a new class of phytohormones that also act as germination stimulants for root parasitic plants, such as Striga spp., and as branching factors for symbiotic arbuscular mycorrhizal fungi. Sources for natural SLs are very limited. Hence, efficient and simple SL analogs are needed for elucidating SL-related biological processes as well as for agricultural applications. Based on the structure of the non-canonical SL methyl carlactonoate, we developed a new, easy to synthesize series of analogs, termed methyl phenlactonoates (MPs), evaluated their efficacy in exerting different SL functions, and determined their affinity for SL receptors from rice and Striga hermonthica. Most of the MPs showed considerable activity in regulating plant architecture, triggering leaf senescence, and inducing parasitic seed germination. Moreover, some MPs outperformed GR24, a widely used SL analog with a complex structure, in exerting particular SL functions, such as modulating Arabidopsis roots architecture and inhibiting rice tillering. Thus, MPs will help in elucidating the functions of SLs and are promising candidates for agricultural applications. Moreover, MPs demonstrate that slight structural modifications clearly impact the efficiency in exerting particular SL functions, indicating that structural diversity of natural SLs may mirror a functional specificity.

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Echinocandins: structural diversity, biosynthesis, and development of antimycotics

Applied Microbiology and Biotechnology ◽

10.1007/s00253-020-11022-y ◽

2020 ◽

Vol 105 (1) ◽

pp. 55-66

Author(s):

Wolfgang Hüttel

Keyword(s):

Isotope Labeling ◽

Current Knowledge ◽

Complex Structure ◽

Hydrolytic Stability ◽

Structural Diversity ◽

Gene Clusters ◽

Special Focus ◽

Key Points ◽

Invasive Mycosis ◽

History Of

Abstract Echinocandins are a clinically important class of non-ribosomal antifungal lipopeptides produced by filamentous fungi. Due to their complex structure, which is characterized by numerous hydroxylated non-proteinogenic amino acids, echinocandin antifungal agents are manufactured semisynthetically. The development of optimized echinocandin structures is therefore closely connected to their biosynthesis. Enormous efforts in industrial research and development including fermentation, classical mutagenesis, isotope labeling, and chemical synthesis eventually led to the development of the active ingredients caspofungin, micafungin, and anidulafungin, which are now used as first-line treatments against invasive mycosis. In the last years, echinocandin biosynthetic gene clusters have been identified, which allowed for the elucidation but also engineering of echinocandin biosynthesis on the molecular level. After a short description of the history of echinocandin research, this review provides an overview of the current knowledge of echinocandin biosynthesis with a special focus of the diverse structural elements, their biosynthetic background, and structure−activity relationships. Key points • Complex and highly oxidized lipopeptides produced by fungi. • Crucial in the design of drugs: side chain, solubility, and hydrolytic stability. • Genetic methods for engineering biosynthesis have recently become available.

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