scholarly journals HCoV-229E spike protein fusion activation by trypsin-like serine proteases is mediated by proteolytic processing in the S2′ region

2018 ◽  
Vol 99 (7) ◽  
pp. 908-912 ◽  
Author(s):  
Ariane Bonnin ◽  
Adeline Danneels ◽  
Jean Dubuisson ◽  
Anne Goffard ◽  
Sandrine Belouzard
Keyword(s):  
Serine Proteases ◽  
Proteolytic Processing ◽  
Spike Protein ◽  
Protein Fusion

TMPRSS2 activates hemagglutinin-esterase glycoprotein of influenza C virus

2021 ◽  
Author(s):  
Ko Sato ◽  
Hideki Hayashi ◽  
Yoshitaka Shimotai ◽  
Mutsuo Yamaya ◽  
Seiji Hongo ◽  
...  
Keyword(s):  
Respiratory Tract ◽  
Serine Proteases ◽  
Influenza A ◽  
Respiratory Illness ◽  
Amino Acid Sequences ◽  
Spike Protein ◽  
Human Airway ◽  
Therapeutic Drugs ◽  
Influenza C Virus ◽  
Step Growth

Influenza C virus (ICV) has only one kind of spike protein, the hemagglutinin-esterase (HE) glycoprotein. HE functions similarly to hemagglutinin (HA) and neuraminidase of the influenza A and B viruses (IAV/IBV). It has a monobasic site, which is cleaved by some host enzyme(s). The cleavage is essential to activating the virus, but the enzyme(s) in the respiratory tract has not been identified. This study investigated whether the host serine proteases, transmembrane protease serine S1, members 2 (TMPRSS2), and human airway trypsin-like protease (HAT), which reportedly cleave HA of IAV/IBV, are involved in HE cleavage. We established TMPRSS2- and HAT-expressing MDCK (MDCK-TMPRSS2, MDCK-HAT) cells. ICV showed multicycle replication with HE cleavage without trypsin in MDCK-TMPRSS2 cells as well as IAV did. The HE cleavage and multicycle replication did not appear in MDCK-HAT cells infected with ICV without trypsin, while HA cleavage and multi-step growth of IAV appeared in the cells. Amino acid sequences of the HE cleavage site in 352 ICV strains were completely preserved. Camostat and nafamostat suppressed the growth of ICV and IAV in human nasal surface epithelial (HNE) cells. Therefore, this study revealed that, at least, TMPRSS2 is involved in HE cleavage and suggested that nafamostat could be a candidate for therapeutic drugs of ICV infection. Importance Influenza C virus (ICV) is a pathogen that causes acute respiratory illness, mostly in children, but there are no anti-ICV drugs. ICV has only one kind of spike protein, the hemagglutinin-esterase (HE) glycoprotein on the virion surface, that possesses receptor binding, receptor destroying, and membrane fusion activities. The HE cleavage is essential for the virus to be activated, but the enzyme(s) in the respiratory tract has not been identified. This study revealed that transmembrane protease serine S1, members 2 (TMPRSS2), and not human airway trypsin-like protease (HAT), is involved in HE cleavage. This is a novel study on the host enzymes involved in HE cleavage, and the result suggests that the host enzymes, such as TMPRSS2, may be a target for therapeutic drugs of the ICV infection.

scholarly journals Spike Protein Fusion Peptide and Feline Coronavirus Virulence

2012 ◽  
Vol 18 (7) ◽  
pp. 1089-1095 ◽  
Author(s):  
Hui-Wen Chang ◽  
Herman F. Egberink ◽  
Rebecca Halpin ◽  
David J. Spiro ◽  
Peter J.M. Rottier
Keyword(s):  
Fusion Peptide ◽  
Spike Protein ◽  
Protein Fusion ◽  
Feline Coronavirus

scholarly journals The cutting edge: membrane-anchored serine protease activities in the pericellular microenvironment

2010 ◽  
Vol 428 (3) ◽  
pp. 325-346 ◽  
Author(s):  
Toni M. Antalis ◽  
Marguerite S. Buzza ◽  
Kathryn M. Hodge ◽  
John D. Hooper ◽  
Sarah Netzel-Arnett
Keyword(s):  
Serine Protease ◽  
Serine Proteases ◽  
Catalytic Domain ◽  
Proteolytic Processing ◽  
Coat Proteins ◽  
Vital Functions ◽  
Human Pathology ◽  
Functional Consequences ◽  
Viral Coat ◽  
Precursor Molecules

The serine proteases of the trypsin-like (S1) family play critical roles in many key biological processes including digestion, blood coagulation, and immunity. Members of this family contain N- or C-terminal domains that serve to tether the serine protease catalytic domain directly to the plasma membrane. These membrane-anchored serine proteases are proving to be key components of the cell machinery for activation of precursor molecules in the pericellular microenvironment, playing vital functions in the maintenance of homoeostasis. Substrates activated by membrane-anchored serine proteases include peptide hormones, growth and differentiation factors, receptors, enzymes, adhesion molecules and viral coat proteins. In addition, new insights into our understanding of the physiological functions of these proteases and their involvement in human pathology have come from animal models and patient studies. The present review discusses emerging evidence for the diversity of this fascinating group of membrane serine proteases as potent modifiers of the pericellular microenvironment through proteolytic processing of diverse substrates. We also discuss the functional consequences of the activities of these proteases on mammalian physiology and disease.

Biochemical Characterization of SARS-CoV-2 Spike Protein Proteolytic Processing

2021 ◽  
pp. 162-194
Author(s):  
Hayat Khan ◽  
Firasat Hussain ◽  
Muhammad Kalim ◽  
Shafi Ullah ◽  
Kashif Rahim ◽  
...  
Keyword(s):  
Biochemical Characterization ◽  
Proteolytic Processing ◽  
Spike Protein

Novel Secretory Vesicle Serpins, Endopin 1 and Endopin 2: Endogenous Protease Inhibitors with Distinct Target Protease Specificities

2002 ◽  
Vol 383 (7-8) ◽  
pp. 1067-1074 ◽  
Author(s):  
V. Y. H. Hook ◽  
S.-R. Hwang
Keyword(s):  
Protease Inhibitors ◽  
Serine Proteases ◽  
Chromaffin Cells ◽  
Cysteine Proteases ◽  
Secretory Vesicle ◽  
Proteolytic Processing ◽  
Neuroendocrine Cells ◽  
Secretory Vesicles ◽  
Subcellular Compartment ◽  
Endogenous Protease

Abstract Secretory vesicles of neuroendocrine cells possess multiple proteases for proteolytic processing of proteins into biologically active peptide components, such as peptide hormones and neurotransmitters. The importance of proteases within secretory vesicles predicts the presence of endogenous protease inhibitors in this subcellular compartment. Notably, serpins represent a diverse class of endogenous protease inhibitors that possess selective target protease specificities, defined by the reactive site loop domains (RSL). In the search for endogenous serpins in model secretory vesicles of neuroendocrine chromaffin cells, the presence of serpins related to α1-antichymotrypsin (ACT) was detected by Western blots with antiACT. Molecular cloning revealed the primary structures of two unique serpins, endopin 1 and endopin 2, that possess homology to ACT. Of particular interest was the observation that distinct RSL domains of these new serpins predicted that endopin 1 would inhibit trypsinlike serine proteases cleaving at basic residues, and endopin 2 would inhibit both elastase and papain that represent serine and cysteine proteases, respectively. Endopin 1 showed selective inhibition of trypsin, but did not inhibit chymotrypsin, elastase, or subtilisin. Endopin 2 demonstrated crossclass inhibition of the cysteine protease papain and the serine protease elastase. Endopin 2 did not inhibit chymotrypsin, trypsin, plasmin, thrombin, furin, or cathepsin B. Endopin 1 and endopin 2 each formed SDSstable complexes with target proteases, a characteristic property of serpins. In neuroendocrine chromaffin cells from adrenal medulla, endopin 1 and endopin 2 were both localized to secretory vesicles. Moreover, the inhibitory activity of endopin 2 was optimized under reducing conditions, which required reduced Cys-374; this property is consistent with the presence of endogenous reducing agents in secretory vesicles in vivo. These new findings demonstrate the presence of unique secretory vesicle serpins, endopin 1 and endopin 2, which possess distinct target protease selectivities. Endopin 1 inhibits trypsinlike proteases; endopin 2 possesses crossclass inhibition for inhibition of papainlike cysteine proteases and elastaselike serine proteases. It will be of interest in future studies to define the endogenous protease targets of these two novel secretory vesicle serpins.

scholarly journals Tumor-Specific Proteolytic Processing of Cyclin E Generates Hyperactive Lower-Molecular-Weight Forms

2001 ◽  
Vol 21 (18) ◽  
pp. 6254-6269 ◽  
Author(s):  
Donald C. Porter ◽  
Ning Zhang ◽  
Christopher Danes ◽  
Mollianne J. McGahren ◽  
Richard M. Harwell ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Tumor Cells ◽  
Serine Proteases ◽  
Cyclin E ◽  
S Phase ◽  
Proteolytic Processing ◽  
Full Length ◽  
Lower Molecular Weight ◽  
Normal Cells

ABSTRACT Cyclin E is a G1 cyclin essential for S-phase entry and has a profound role in oncogenesis. Previously this laboratory found that cyclin E is overexpressed and present in lower-molecular-weight (LMW) isoforms in breast cancer cells and tumor tissues compared to normal cells and tissues. Such alteration of cyclin E is linked to poor patient outcome. Here we report that the LMW forms of cyclin E are hyperactive biochemically and they can more readily induce G1-to-S progression in transfected normal cells than the full-length form of the protein can. Through biochemical and mutational analyses we have identified two proteolytically sensitive sites in the amino terminus of human cyclin E that are cleaved to generate the LMW isoforms found in tumor cells. Not only are the LMW forms of cyclin E functional, as they phosphorylate substrates such as histone H1 and GST-Rb, but also their activities are higher than the full-length cyclin E. These nuclear localized LMW forms of cyclin E are also biologically functional, as their overexpression in normal cells increases the ability of these cells to enter S and G2/M. Lastly, we show that cyclin E is selectively cleaved in vitro by the elastase class of serine proteases to generate LMW forms similar to those observed in tumor cells. These studies suggest that the defective entry into and exit from S phase by tumor cells is in part due to the proteolytic processing of cyclin E, which generates hyperactive LMW isoforms whose activities have been modified from that of the full-length protein.

scholarly journals Full-Length Computational Model of the SARS-CoV-2 Spike Protein and Its Implications for a Viral Membrane Fusion Mechanism

Viruses ◽  
2021 ◽  
Vol 13 (6) ◽  
pp. 1126
Author(s):  
Wataru Nishima ◽  
Marta Kulik
Keyword(s):  
Membrane Fusion ◽  
Neutralizing Antibody ◽  
Infection Process ◽  
Proteolytic Processing ◽  
Full Length ◽  
Spike Protein ◽  
Fusion Model ◽  
Protein Uptake ◽  
Host Membrane ◽  
Short Time

The SARS-CoV-2 virus has now become one of the greatest causes of infectious death and morbidity since the 1918 flu pandemic. Substantial and unprecedented progress has been made in the elucidation of the viral infection process in a short time; however, our understanding of the structure–function dynamics of the spike protein during the membrane fusion process and viral uptake remains incomplete. Employing computational approaches, we use full-length structural models of the SARS-CoV-2 spike protein integrating Cryo-EM images and biophysical properties, which fill the gaps in our understanding. We propose a membrane fusion model incorporating structural transitions associated with the proteolytic processing of the spike protein, which initiates and regulates a series of events to facilitate membrane fusion and viral genome uptake. The membrane fusion mechanism highlights the notable role of the S1 subunit and eventual mature spike protein uptake through the host membrane. Our comprehensive view accounts for distinct neutralizing antibody binding effects targeting the spike protein and the enhanced infectivity of the SARS-CoV-2 variant.

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