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Author(s):  
Christin Bartlitz ◽  
Rafał Kolenda ◽  
Jarosław Chilimoniuk ◽  
Krzysztof Grzymajło ◽  
Stefan Rödiger ◽  
...  

Pathogenic bacteria, such as enteropathogenic (EPEC) and enterotoxigenic Escherichia coli (ETEC), cause diarrhea in mammals. In particular, E. coli colonize and infect the gastrointestinal tract via type 1 fimbriae (T1F). Here the major zymogen granule membrane glycoprotein 2 (GP2) acts as host cell receptor. GP2 is also secreted by the pancreas and various mucous glands, interacting with luminal type 1 fimbriae-positive E. coli . It is unknown whether GP2 isoforms demonstrate specific E. coli pathotype binding. In this study, we investigated interactions of human, porcine and bovine EPEC, ETEC as well as commensal E. coli isolates with human, porcine and bovine GP2. We first defined pathotype- and host-associated FimH variants. Secondly, we could prove that GP2 isoforms bound to FimH variants to varying degrees. However, the GP2-FimH interactions did not seem to be influenced by the host specificity of E. coli . In contrast, soluble GP2 affected ETEC infection and phagocytosis rates of macrophages. Pre-incubation of ETEC pathotype with GP2 reduced infection of cell lines. Furthermore, pre-incubation of E. coli with GP2 improved the phagocytosis rate of macrophages. Our findings suggest that GP2 plays a role in the defense against E. coli infection and in the corresponding host immune response. IMPORTANCE Infection by pathogenic bacteria such as certain Escherichia coli pathotypes results in diarrhea in mammals. Pathogens, including zoonotic agents, can infect different hosts or show host-specificity. There are Escherichia coli strains which are frequently transmitted between humans and animals, whereas other Escherichia coli strains tend to colonize only one host. This host-specificity is still not fully understood. We show that glycoprotein 2 is a selective receptor for particular Escherichia coli strains or variants of the adhesin FimH but not a selector for a species-specific Escherichia coli group. We demonstrate that GP2 is involved in the regulation of colonization and infection and thus represents a molecule of interest for the prevention or treatment of disease.


Blood ◽  
2021 ◽  
Vol 138 (Supplement 1) ◽  
pp. 352-352
Author(s):  
Nanyan Zhang ◽  
Brian R. Curtis ◽  
Peter J. Newman

Abstract Sialic acids occupy the terminal position of glycan chains, and have the potential to influence the antigenicity of glycoproteins. Antibody binding sites on a glycoprotein can be solely protein in nature, or can include or be affected by nearby glycan chains, which may either mask the epitope, or conversely comprise part of the antibody binding site. The polymorphisms responsible for formation of the Human Platelet Alloantigens (HPA)-3 (Ile843Ser) and HPA-9 (Val837Met) are next to each other near the C-terminus of the extracellular domain of platelet membrane glycoprotein (GP)IIb, and are adjacent to sialyl-Core 1 O-glycans that emanate from serines 845 and 847. Previous studies have shown that these O-linked glycans are required to support the binding of some of HPA-3a alloantibodies. Loss of these glycans, especially terminal sialic acid residues, during platelet storage or preparation, can present major difficulties in detecting clinically important anti-HPA-3a alloantibodies in suspected cases of fetal/neonatal alloimmune thrombocytopenia (FNAIT). Similarly, detection and identification of anti-HPA-9b alloantibodies from FNAIT patient sera can also be extremely challenging, resulting in the inability to resolve clinical cases of this bleeding disorder. Whether the nearby O-glycans on serines 845 and 847 of GPIIb affect the antigenicity of HPA-9b, and/or influence the binding of anti-HPA-9b alloantibodies in clinically significant cases of FNAIT is unknown. We previously reported the generation of bioengineered, HLA class I-negative, HPA-9a or -9b allele-specific megakaryocytes (MKs) from human induced pluripotent stem cells (iPSCs) that are suitable for whole-cell flow cytometric detection of anti-HPA-9b alloantibodies (Blood 2019;134(22):e1-e8). Unexpectedly, treatment of these allele-specific MKs with neuraminidase actually enhanced the binding of anti-HPA-9b alloantibodies, suggesting that terminal sialic acids on GPIIb partially mask the HPA-9b epitope. To test the hypothesis that removal of terminal sialic acids on nearby O-glycans, or removal of the entire O-glycan chains emanating from Ser845/847 of GPIIb, might enhance the detection of anti-HPA-9b patient alloantibodies, we created a series of deletion mutants in two major sialidases, ST3GAL1 and ST3GAL2, known to be responsible for transferring terminal sialic acid residues to Core 1 O-glycans, in our HPA-9a and -9b allele-specific iPSCs. Immunoprecipitation/western blot analysis confirmed the complete removal of terminal sialic acids on the O-glycan chains of GPIIb in ST3GAL1/2 knockout (KO) iPSC-derived MKs, as reported by the binding of the lectin PNA to the exposed Core 1 structure on GPIIb. These sialylation-deficient ST3GAL1/2 KO HPA-9b MKs exhibited dramatically increased anti-HPA-9b alloantibody binding, further confirming the notion that HPA-9b epitopes are partially masked by terminal sialic acids on nearby GPIIb O-glycan chains. Finally, allele-specific iPSCs lacking the complete O-glycan chains attached to serines 845 and 847 of GPIIb were generated by mutating those residues to alanines using a similar CRISPR/Cas9 gene editing approach. Interestingly, O-glycan chain-deficient Ala845/847 mutant MKs carrying the HPA-9b polymorphism exhibited slightly to moderately reduced binding of anti-HPA-9b alloantibodies, indicating that the presence of the Core 1 O-glycan chains attached to GPIIb serine residues 845 and 847 contribute to the presentation of the HPA-9b epitope - perhaps by stabilizing the conformation of the glycoprotein in this region. Taken together, these data suggest that detection of anti-HPA-9b alloantibodies may be enhanced through the use of iPSC-derived HPA-9b-specific MKs that have been genetically altered to lack nearby terminal sialic acid residues, but retain the glycan chains to which they are attached. Disclosures Curtis: Rallybio: Consultancy. Newman: Rallybio: Consultancy, Research Funding.


Molecules ◽  
2021 ◽  
Vol 26 (20) ◽  
pp. 6171
Author(s):  
Amr El-Demerdash ◽  
Afnan Hassan ◽  
Tarek Mohamed Abd Abd El-Aziz ◽  
James D. Stockand ◽  
Reem K. Arafa

There have been more than 150 million confirmed cases of SARS-CoV-2 since the beginning of the pandemic in 2019. By June 2021, the mortality from such infections approached 3.9 million people. Despite the availability of a number of vaccines which provide protection against this virus, the evolution of new viral variants, inconsistent availability of the vaccine around the world, and vaccine hesitancy, in some countries, makes it unreasonable to rely on mass vaccination alone to combat this pandemic. Consequently, much effort is directed to identifying potential antiviral treatments. Marine brominated tyrosine alkaloids are recognized to have antiviral potential. We test here the antiviral capacity of fourteen marine brominated tyrosine alkaloids against five different target proteins from SARS-CoV-2, including main protease (Mpro) (PDB ID: 6lu7), spike glycoprotein (PDB ID: 6VYB), nucleocapsid phosphoprotein (PDB ID: 6VYO), membrane glycoprotein (PDB ID: 6M17), and non-structural protein 10 (nsp10) (PDB ID: 6W4H). These marine alkaloids, particularly the hexabrominated compound, fistularin-3, shows promising docking interactions with predicted binding affinities (S-score = −7.78, −7.65, −6.39, −6.28, −8.84 Kcal/mol) for the main protease (Mpro) (PDB ID: 6lu7), spike glycoprotein (PDB ID: 6VYB), nucleocapsid phosphoprotein (PDB ID: 6VYO), membrane glycoprotein (PDB ID: 6M17), and non-structural protein 10 (nsp10) (PDB ID: 6W4H), respectively, where it forms better interactions with the protein pockets than the native interaction. It also shows promising molecular dynamics, pharmacokinetics, and toxicity profiles. As such, further exploration of the antiviral properties of fistularin-3 against SARS-CoV-2 is merited.


2021 ◽  
Author(s):  
Pinky Debnath ◽  
Umama Khan ◽  
Md. Salauddin Khan

The acute respiratory disease induced by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has become a global epidemic in just less than a year by the first half of 2020. The subsequent efficient human-to-human transmission of this virus eventually affected millions of people worldwide. The most devastating thing is that the infection rate is continuously uprising and resulting in significant mortality especially among the older age population and those with health comorbidities.This enveloped, positive-sense RNA virus is chiefly responsible for the infection of the upper respiratory system. The virulence of the SARS-CoV-2 is mostly regulated by its proteins like entry to the host cell through fusion mechanism, fusion of infected cells with neighboring uninfected cells to spread the virus, inhibition of host gene expression, cellular differentiation, apoptosis, mitochondrial biogenesis, etc. But very little is known about the protein structures and functionalities. Therefore, the main purpose of this study is to learn more about these proteins through bioinformatics approaches. In this study, ORF10, ORF7b, ORF7a, ORF6, membrane glycoprotein, and envelope protein have been selected from a Bangladeshi Coronavirus strain G039392 and a number of bioinformatics tools MEGA-X-V10.1.7 PONDR, ProtScale, ProtParam, SCRIBER NetSurfP v2.0, IntFOLD UCSF Chimera and PyMol) and strategies were implemented for multiple sequence alignment and phylogeny analysis with 9 different variants, predicting hydropathicity, amino acid compositions, protein binding propensity, protein disorders, 2D and 3D protein modeling. Selected proteins were characterized as highly flexible, structurally and electrostatically extremely stable, ordered, biologically active, hydrophobic, and closely related to the proteins of different variants. This detailed information regarding the characterization and structure of proteins of SARS-CoV-2 Bangladeshi variant was performed for the first time ever to unveil the deep mechanism behind the virulence features and also, this robust appraisal paves the future way for molecular docking, vaccine development targeting these characterized proteins.


Author(s):  
PRIYANKA RAJBHAR ◽  
DIKSHANT SINGH ◽  
RUKHSAR FATIMA ◽  
RUCHI YADAV

Objective: Coronaviruses are a group of similar viruses which cause fatal infection and responsible for affecting the upper respiratory tract in many organisms. Throughout the time these viruses have been found to affect human life by causing major pandemics like SARS, MERS and COVID-19 due to their high rate of mutation and zoonotic transmission. Repurposing of a drug could be a solution for this challenge, as many previously available drugs hold great potential to act as a drug molecule. Interfering this interaction could be a potent mechanism to stop the viral infection and propagation. Methods: In the current study we have predicted the evolutionary relationship of nCoV using three viral proteins Nucleocapsid phosphoprotein, membrane glycoprotein and Envelop protein with accession number YP_009724397, YP_009724393 and YP_009724392 respectively. Phylogenetic tree was constructed and evaluated using the bootstrap method. Homology modeling and docking studies has been done to identify the interaction and binding affinity of SARS drugs. Results: Phylogenetic tree shows that Nucleocapsid phosphoprotein is originated from Hypsugo Bat Coronavirus, Membrane glycoprotein is originated from MERS Corona Virus and Envelop proteins have originated from Ferret coronavirus. From the docking result we concluded that Precose (glide score-8.372) shows that it has stable and strong interaction with Spike glycoprotein. Conclusion: Precose which is commonly known as Acarbose can act as a potential inhibitor for the spike glycoprotein. This paper described and highlighted the importance of repurposing of the previously available drug to act as a potent inhibitor in the newly discovered or novel diseases.


2021 ◽  
Vol 66 (5) ◽  
pp. 737-750
Author(s):  
A. S. Urban ◽  
Ya. V. Bershatskii ◽  
K. V. Pavlov ◽  
E. V. Bocharov

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