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1.
Int J Mol Sci ; 21(16)2020 Aug 06.
Article in English | MEDLINE | ID: covidwho-1934101

ABSTRACT

The recently discovered 340-cavity in influenza neuraminidase (NA) N6 and N7 subtypes has introduced new possibilities for rational structure-based drug design. However, the plasticity of the 340-loop (residues 342-347) and the role of the 340-loop in NA activity and substrate binding have not been deeply exploited. Here, we investigate the mechanism of 340-cavity formation and demonstrate for the first time that seven of nine NA subtypes are able to adopt an open 340-cavity over 1.8 µs total molecular dynamics simulation time. The finding that the 340-loop plays a role in the sialic acid binding pathway suggests that the 340-cavity can function as a druggable pocket. Comparing the open and closed conformations of the 340-loop, the side chain orientation of residue 344 was found to govern the formation of the 340-cavity. Additionally, the conserved calcium ion was found to substantially influence the stability of the 340-loop. Our study provides dynamical evidence supporting the 340-cavity as a druggable hotspot at the atomic level and offers new structural insight in designing antiviral drugs.


Subject(s)
Antiviral Agents/pharmacology , Drug Development , Neuraminidase/chemistry , Orthomyxoviridae/enzymology , Binding Sites , Calcium/chemistry , Ions , Models, Molecular , Molecular Dynamics Simulation , N-Acetylneuraminic Acid/chemistry , Principal Component Analysis , Protein Structure, Secondary , Thermodynamics
2.
Angew Chem Int Ed Engl ; 61(18): e202201432, 2022 04 25.
Article in English | MEDLINE | ID: covidwho-1729097

ABSTRACT

The interaction of the SARS CoV2 spike glycoprotein with two sialic acid-containing trisaccharides (α2,3 and α2,6 sialyl N-acetyllactosamine) has been demonstrated by NMR. The NMR-based distinction between the signals of those sialic acids in the glycans covalently attached to the spike protein and those belonging to the exogenous α2,3 and α2,6 sialyl N-acetyllactosamine ligands has been achieved by synthesizing uniformly 13 C-labelled trisaccharides at the sialic acid and galactose moieties. STD-1 H,13 C-HSQC NMR experiments elegantly demonstrate the direct interaction of the sialic acid residues of both trisaccharides with additional participation of the galactose moieties, especially for the α2,3-linked analogue. Additional experiments with the spike protein in the presence of a specific antibody for the N-terminal domain and with the isolated receptor binding and N-terminal domains of the spike protein unambiguously show that the sialic acid binding site is located at the N-terminal domain.


Subject(s)
COVID-19 , Spike Glycoprotein, Coronavirus , Binding Sites , Galactose , Humans , N-Acetylneuraminic Acid/chemistry , SARS-CoV-2 , Sialic Acids/chemistry , Spike Glycoprotein, Coronavirus/chemistry , Trisaccharides
3.
Virology ; 562: 142-148, 2021 10.
Article in English | MEDLINE | ID: covidwho-1331288

ABSTRACT

SARS-CoV, MERS-CoV, and potentially SARS-CoV-2 emerged as novel human coronaviruses following cross-species transmission from animal hosts. Although the receptor binding characteristics of human coronaviruses are well documented, the role of carbohydrate binding in addition to recognition of proteinaceous receptors has not been fully explored. Using natural glycan microarray technology, we identified N-glycans in the human lung that are recognized by various human and animal coronaviruses. All viruses tested, including SARS-CoV-2, bound strongly to a range of phosphorylated, high mannose N-glycans and to a very specific set of sialylated structures. Examination of two linked strains, human CoV OC43 and bovine CoV Mebus, reveals shared binding to the sialic acid form Neu5Gc (not found in humans), supporting the evidence for cross-species transmission of the bovine strain. Our findings, revealing robust recognition of lung glycans, suggest that these receptors could play a role in the initial stages of coronavirus attachment and entry.


Subject(s)
COVID-19/virology , Host Microbial Interactions/physiology , Middle East Respiratory Syndrome Coronavirus/metabolism , Polysaccharides/metabolism , SARS-CoV-2/metabolism , Animals , Cattle , Humans , Lung/metabolism , Mannose/chemistry , Middle East Respiratory Syndrome Coronavirus/physiology , N-Acetylneuraminic Acid/chemistry , Phosphorylation , Protein Array Analysis , Protein Binding , SARS-CoV-2/physiology , Spike Glycoprotein, Coronavirus/chemistry , Spike Glycoprotein, Coronavirus/physiology
4.
Nat Chem ; 13(5): 496-503, 2021 05.
Article in English | MEDLINE | ID: covidwho-1145994

ABSTRACT

The transmission of viruses from animal reservoirs to humans poses major threats to public health. Preparedness for future zoonotic outbreaks requires a fundamental understanding of how viruses of animal origin have adapted to binding to a cell surface component and/or receptor of the new host. Here we report on the specificities of human and animal viruses that engage with O-acetylated sialic acid, which include betacoronaviruses, toroviruses and influenza C and D viruses. Key to these studies was the development of a chemoenzymatic methodology that can provide almost any sialate-acetylation pattern. A collection of O-acetylated sialoglycans was printed as a microarray for the determination of receptor specificity. These studies showed host-specific patterns of receptor recognition and revealed that three distinct human respiratory viruses uniquely bind 9-O-acetylated α2,8-linked disialoside. Immunofluorescence and cell entry studies support that such a glycotope as part of a ganglioside is a functional receptor for human coronaviruses.


Subject(s)
N-Acetylneuraminic Acid/chemistry , Respiratory Tract Infections/virology , Viruses/pathogenicity , Humans , Transfection
5.
Anal Bioanal Chem ; 413(29): 7295-7303, 2021 Dec.
Article in English | MEDLINE | ID: covidwho-1274805

ABSTRACT

The coronavirus disease 2019 (COVID-19) pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) presents a serious threat to human health all over the world. The development of effective vaccines has been focusing on the spike (S) glycoprotein, which mediates viral invasion to human cells through its interaction with the angiotensin-converting enzyme 2 (ACE2) receptor. In this work, we perform analytical characterization of N- and O-linked glycosylation of the SARS-CoV-2 S glycoprotein. We explore the novel use of dual-functionalized titanium (IV)-immobilized metal affinity chromatography (Ti-IMAC) material for simultaneous enrichment and separation of neutral and sialyl glycopeptides of a recombinant SARS-CoV-2 S glycoprotein from HEK293 cells. This strategy helps eliminate signal suppression from neutral glycopeptides for the detection of sialyl glycopeptides and improves the glycoform coverage of the S protein. We profiled 19 of its 22 potential N-glycosylated sites with 398 unique glycoforms using the dual-functional Ti-IMAC approach, which exhibited improvement of coverage by 1.6-fold compared to the conventional hydrophilic interaction chromatography (HILIC) glycopeptide enrichment method. We also identified O-linked glycosylation site that was not found using the conventional HILIC approach. In addition, we reported on the identification of mannose-6-phosphate (M6P) glycosylation, which substantially expands the current knowledge of the spike protein's glycosylation landscape and enables future investigation into the influence of M6P glycosylation of the spike protein on its cell entry.


Subject(s)
Glycopeptides/isolation & purification , N-Acetylneuraminic Acid/chemistry , SARS-CoV-2/chemistry , Spike Glycoprotein, Coronavirus/chemistry , Amino Acid Sequence , Chromatography, Liquid/methods , Glycopeptides/chemistry , HEK293 Cells , Humans , Mannosephosphates/chemistry , Static Electricity , Tandem Mass Spectrometry/methods
6.
Comput Biol Med ; 122: 103849, 2020 07.
Article in English | MEDLINE | ID: covidwho-574849

ABSTRACT

SARS-CoV and SARS-CoV-2 do not appear to have functions of a hemagglutinin and neuraminidase. This is a mystery, because sugar binding activities appear essential to many other viruses including influenza and even most other coronaviruses in order to bind to and escape from the glycans (sugars, oligosaccharides or polysaccharides) characteristic of cell surfaces and saliva and mucin. The S1 N terminal Domains (S1-NTD) of the spike protein, largely responsible for the bulk of the characteristic knobs at the end of the spikes of SARS-CoV and SARS-CoV-2, are here predicted to be "hiding" sites for recognizing and binding glycans containing sialic acid. This may be important for infection and the ability of the virus to locate ACE2 as its known main host cell surface receptor, and if so it becomes a pharmaceutical target. It might even open up the possibility of an alternative receptor to ACE2. The prediction method developed, which uses amino acid residue sequence alone to predict domains or proteins that bind to sialic acids, is naïve, and will be advanced in future work. Nonetheless, it was surprising that such a very simple approach was so useful, and it can easily be reproduced in a very few lines of computer program to help make quick comparisons between SARS-CoV-2 sequences and to consider the effects of viral mutations.


Subject(s)
Betacoronavirus/chemistry , Computational Biology , Coronavirus Infections/virology , Pneumonia, Viral/virology , Spike Glycoprotein, Coronavirus/chemistry , Algorithms , Amino Acid Motifs , Binding Sites , COVID-19 , Humans , Molecular Conformation , N-Acetylneuraminic Acid/chemistry , Pandemics , Polysaccharides/chemistry , SARS Virus , SARS-CoV-2 , Tryptophan/chemistry
7.
Angew Chem Int Ed Engl ; 59(30): 12417-12422, 2020 07 20.
Article in English | MEDLINE | ID: covidwho-343407

ABSTRACT

Flexible multivalent 3D nanosystems that can deform and adapt onto the virus surface via specific ligand-receptor multivalent interactions can efficiently block virus adhesion onto the cell. We here report on the synthesis of a 250 nm sized flexible sialylated nanogel that adapts onto the influenza A virus (IAV) surface via multivalent binding of its sialic acid (SA) residues with hemagglutinin spike proteins on the virus surface. We could demonstrate that the high flexibility of sialylated nanogel improves IAV inhibition by 400 times as compared to a rigid sialylated nanogel in the hemagglutination inhibition assay. The flexible sialylated nanogel efficiently inhibits the influenza A/X31 (H3N2) infection with IC50 values in low picomolar concentrations and also blocks the virus entry into MDCK-II cells.


Subject(s)
Antiviral Agents/pharmacology , Influenza A virus/drug effects , N-Acetylneuraminic Acid/chemistry , Nanogels/chemistry , Animals , Antiviral Agents/chemistry , Dogs , Influenza A virus/physiology , Inhibitory Concentration 50 , Madin Darby Canine Kidney Cells , Microscopy, Atomic Force , Microscopy, Fluorescence , Virus Internalization/drug effects
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