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J Virol ; 95(16): e0018721, 2021 07 26.
Article in English | MEDLINE | ID: covidwho-1486048


Subversion of the host cell cycle to facilitate viral replication is a common feature of coronavirus infections. Coronavirus nucleocapsid (N) protein can modulate the host cell cycle, but the mechanistic details remain largely unknown. Here, we investigated the effects of manipulation of porcine epidemic diarrhea virus (PEDV) N protein on the cell cycle and the influence on viral replication. Results indicated that PEDV N induced Vero E6 cell cycle arrest at S-phase, which promoted viral replication (P < 0.05). S-phase arrest was dependent on the N protein nuclear localization signal S71NWHFYYLGTGPHADLRYRT90 and the interaction between N protein and p53. In the nucleus, the binding of N protein to p53 maintained consistently high-level expression of p53, which activated the p53-DREAM pathway. The key domain of the N protein interacting with p53 was revealed to be S171RGNSQNRGNNQGRGASQNRGGNN194 (NS171-N194), in which G183RG185 are core residues. NS171-N194 and G183RG185 were essential for N-induced S-phase arrest. Moreover, small molecular drugs targeting the NS171-N194 domain of the PEDV N protein were screened through molecular docking. Hyperoside could antagonize N protein-induced S-phase arrest by interfering with interaction between N protein and p53 and inhibit viral replication (P < 0.05). The above-described experiments were also validated in porcine intestinal cells, and data were in line with results in Vero E6 cells. Therefore, these results reveal the PEDV N protein interacts with p53 to activate the p53-DREAM pathway, and subsequently induces S-phase arrest to create a favorable environment for virus replication. These findings provide new insight into the PEDV-host interaction and the design of novel antiviral strategies against PEDV. IMPORTANCE Many viruses subvert the host cell cycle to create a cellular environment that promotes viral growth. PEDV, an emerging and reemerging coronavirus, has led to substantial economic loss in the global swine industry. Our study is the first to demonstrate that PEDV N-induced cell cycle arrest during the S-phase promotes viral replication. We identified a novel mechanism of PEDV N-induced S-phase arrest, where the binding of PEDV N protein to p53 maintains consistently high levels of p53 expression in the nucleus to mediate S-phase arrest by activating the p53-DREAM pathway. Furthermore, a small molecular compound, hyperoside, targeted the PEDV N protein, interfering with the interaction between the N protein and p53 and, importantly, inhibited PEDV replication by antagonizing cell cycle arrest. This study reveals a new mechanism of PEDV-host interaction and also provides a novel antiviral strategy for PEDV. These data provide a foundation for further research into coronavirus-host interactions.

Antiviral Agents/pharmacology , Coronavirus Nucleocapsid Proteins/chemistry , Host-Pathogen Interactions/drug effects , Porcine epidemic diarrhea virus/drug effects , Quercetin/analogs & derivatives , Tumor Suppressor Protein p53/chemistry , Amino Acid Sequence , Animals , Antiviral Agents/chemistry , Binding Sites , Cell Line , Chlorocebus aethiops , Coronavirus Infections/drug therapy , Coronavirus Infections/genetics , Coronavirus Infections/metabolism , Coronavirus Infections/virology , Coronavirus Nucleocapsid Proteins/antagonists & inhibitors , Coronavirus Nucleocapsid Proteins/genetics , Coronavirus Nucleocapsid Proteins/metabolism , Epithelial Cells/drug effects , Epithelial Cells/virology , Gene Expression Regulation , High-Throughput Screening Assays , Host-Pathogen Interactions/genetics , Molecular Docking Simulation , Nuclear Localization Signals , Porcine epidemic diarrhea virus/genetics , Porcine epidemic diarrhea virus/metabolism , Protein Binding , Protein Conformation , Protein Interaction Domains and Motifs , Quercetin/chemistry , Quercetin/pharmacology , S Phase Cell Cycle Checkpoints/drug effects , S Phase Cell Cycle Checkpoints/genetics , Signal Transduction , Swine , Swine Diseases/drug therapy , Swine Diseases/genetics , Swine Diseases/metabolism , Swine Diseases/virology , Tumor Suppressor Protein p53/antagonists & inhibitors , Tumor Suppressor Protein p53/genetics , Tumor Suppressor Protein p53/metabolism , Vero Cells , Virus Replication/drug effects
Biomolecules ; 11(7)2021 07 19.
Article in English | MEDLINE | ID: covidwho-1328091


Proteins of the major histocompatibility complex (MHC) class I, or human leukocyte antigen (HLA) in humans interact with endogenous peptides and present them to T cell receptors (TCR), which in turn tune the immune system to recognize and discriminate between self and foreign (non-self) peptides. Of especial importance are peptides derived from tumor-associated antigens. T cells recognizing these peptides are found in cancer patients, but not in cancer-free individuals. What stimulates this recognition, which is vital for the success of checkpoint based therapy? A peptide derived from the protein p53 (residues 161-169 or p161) was reported to show this behavior. T cells recognizing this unmodified peptide could be further stimulated in vitro to create effective cancer killing CTLs (cytotoxic T lymphocytes). We hypothesize that the underlying difference may arise from post-translational glycosylation of p161 in normal individuals, likely masking it against recognition by TCR. Defects in glycosylation in cancer cells may allow the presentation of the native peptide. We investigate the structural consequences of such peptide glycosylation by investigating the associated structural dynamics.

HLA-A24 Antigen/chemistry , HLA-A24 Antigen/metabolism , Receptors, Antigen, T-Cell/metabolism , Tumor Suppressor Protein p53/metabolism , Acetylglucosamine/metabolism , Glycosylation , Human Immunodeficiency Virus Proteins/chemistry , Human Immunodeficiency Virus Proteins/metabolism , Humans , Hydrogen Bonding , Models, Molecular , Molecular Dynamics Simulation , Peptide Fragments/chemistry , Peptide Fragments/metabolism , Protein Conformation , Receptors, Antigen, T-Cell/chemistry , Tumor Suppressor Protein p53/chemistry
Sci Rep ; 11(1): 10475, 2021 05 18.
Article in English | MEDLINE | ID: covidwho-1233721


Infection by the severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) causes COVID-19 disease. Therapeutic antibodies are being developed that interact with the viral spike proteins to limit viral infection of epithelium. We have applied a method to dramatically improve the performance of anti-SARS-CoV-2 antibodies by enhancing avidity through multimerization using simple engineering to yield tetrameric antibodies. We have re-engineered six anti-SARS-CoV-2 antibodies using the human p53 tetramerization domain, including three clinical trials antibodies casirivimab, imdevimab and etesevimab. The method yields tetrameric antibodies, termed quads, that retain efficient binding to the SARS-CoV-2 spike protein, show up to two orders of magnitude enhancement in neutralization of pseudovirus infection and retain potent interaction with virus variant of concern spike proteins. The tetramerization method is simple, general and its application is a powerful methodological development for SARS-CoV-2 antibodies that are currently in pre-clinical and clinical investigation.

SARS-CoV-2/metabolism , Single-Chain Antibodies/immunology , Spike Glycoprotein, Coronavirus/immunology , Antibodies, Neutralizing/immunology , Antibodies, Neutralizing/therapeutic use , Antigen-Antibody Reactions , COVID-19/drug therapy , COVID-19/virology , Enzyme-Linked Immunosorbent Assay , HEK293 Cells , Humans , Neutralization Tests , Protein Domains , Protein Multimerization , Recombinant Proteins/biosynthesis , Recombinant Proteins/immunology , Recombinant Proteins/isolation & purification , Recombinant Proteins/therapeutic use , SARS-CoV-2/immunology , SARS-CoV-2/isolation & purification , Single-Chain Antibodies/chemistry , Single-Chain Antibodies/genetics , Single-Chain Antibodies/therapeutic use , Surface Plasmon Resonance , Tumor Suppressor Protein p53/chemistry