scholarly journals TMPRSS12 Is an Activating Protease for Subtype B Avian Metapneumovirus

2016 ◽  
Vol 90 (24) ◽  
pp. 11231-11246 ◽  
Author(s):  
Bingling Yun ◽  
Yao Zhang ◽  
Yongzhen Liu ◽  
Xiaolu Guan ◽  
Yongqiang Wang ◽  
...  

ABSTRACTThe entry of avian metapneumovirus (aMPV) into host cells initially requires the fusion of viral and cell membranes, which is exclusively mediated by fusion (F) protein. Proteolysis of aMPV F protein by endogenous proteases of host cells allows F protein to induce membrane fusion; however, these proteases have not been identified. Here, we provide the first evidence that the transmembrane serine protease TMPRSS12 facilitates the cleavage of subtype B aMPV (aMPV/B) F protein. We found that overexpression of TMPRSS12 enhanced aMPV/B F protein cleavage, F protein fusogenicity, and viral replication. Subsequently, knockdown of TMPRSS12 with specific small interfering RNAs (siRNAs) reduced aMPV/B F protein cleavage, F protein fusogenicity, and viral replication. We also found a cleavage motif in the aMPV/B F protein (amino acids 100 and 101) that was recognized by TMPRSS12. The histidine, aspartic acid, and serine residue (HDS) triad of TMPRSS12 was shown to be essential for the proteolysis of aMPV/B F protein via mutation analysis. Notably, we observed TMPRSS12 mRNA expression in target organs of aMPV/B in chickens. Overall, our results indicate that TMPRSS12 is crucial for aMPV/B F protein proteolysis and aMPV/B infectivity and that TMPRSS12 may serve as a target for novel therapeutics and prophylactics for aMPV.IMPORTANCEProteolysis of the aMPV F protein is a prerequisite for F protein-mediated membrane fusion of virus and cell and for aMPV infection; however, the proteases usedin vitroandvivoare not clear. A combination of analyses, including overexpression, knockdown, and mutation methods, demonstrated that the transmembrane serine protease TMPRSS12 facilitated cleavage of subtype B aMPV (aMPV/B) F protein. Importantly, we located the motif in the aMPV/B F protein recognized by TMPRSS12 and the catalytic triad in TMPRSS12 that facilitated proteolysis of the aMPV/B F protein. This is the first report on TMPRSS12 as a protease for proteolysis of viral envelope glycoproteins. Our study will shed light on the mechanism of proteolysis of aMPV F protein and pathogenesis of aMPV.

2017 ◽  
Vol 28 (26) ◽  
pp. 3801-3814 ◽  
Author(s):  
Sunandini Chandra ◽  
Raju Kalaivani ◽  
Manoj Kumar ◽  
Narayanaswamy Srinivasan ◽  
Debi P. Sarkar

Reconstituted Sendai viral envelopes (virosomes) are well recognized for their promising potential in membrane fusion–mediated delivery of bioactive molecules to liver cells. Despite the known function of viral envelope glycoproteins in catalyzing fusion with cellular membrane, the role of host cell proteins remains elusive. Here, we used two-dimensional differential in-gel electrophoresis to analyze hepatic cells in early response to virosome-induced membrane fusion. Quantitative mass spectrometry together with biochemical analysis revealed that villin, an actin-modifying protein, is differentially up-regulated and phosphorylated at threonine 206—an early molecular event during membrane fusion. We found that villin influences actin dynamics and that this influence, in turn, promotes membrane mixing through active participation of Sendai viral envelope glycoproteins. Modulation of villin in host cells also resulted in a discernible effect on the entry and egress of progeny Sendai virus. Taken together, these results suggest a novel mechanism of regulated viral entry in animal cells mediated by host factor villin.


2020 ◽  
Vol 94 (12) ◽  
Author(s):  
Ayako Ueo ◽  
Marie Kubota ◽  
Yuta Shirogane ◽  
Shinji Ohno ◽  
Takao Hashiguchi ◽  
...  

ABSTRACT Mumps virus (MuV), an enveloped RNA virus of the Paramyxoviridae family and the causative agent of mumps, affects the salivary glands and other glandular tissues as well as the central nervous system. The virus enters the cell by inducing the fusion of its envelope with the plasma membrane of the target cell. Membrane fusion is mediated by MuV envelope proteins: the hemagglutinin-neuraminidase and fusion (F) protein. Cleavage of the MuV F protein (MuV-F) into two subunits by the cellular protease furin is a prerequisite for fusion and virus infectivity. Here, we show that 293T (a derivative of HEK293) cells do not produce syncytia upon expression of MuV envelope proteins or MuV infection. This failure is caused by the inefficient MuV-F cleavage despite the presence of functional furin in 293T cells. An expression cloning strategy revealed that overexpression of lysosome-associated membrane proteins (LAMPs) confers on 293T cells the ability to produce syncytia upon expression of MuV envelope proteins. The LAMP family comprises the ubiquitously expressed LAMP1 and LAMP2, the interferon-stimulated gene product LAMP3, and the cell type-specific proteins. The expression level of the LAMP3 gene, but not of LAMP1 and LAMP2 genes, differed markedly between 293T and HEK293 cells. Overexpression of LAMP1, LAMP2, or LAMP3 allowed 293T cells to process MuV-F efficiently. Furthermore, these LAMPs were found to interact with both MuV-F and furin. Our results indicate that LAMPs support the furin-mediated cleavage of MuV-F and that, among them, LAMP3 may be critical for the process, at least in certain cells. IMPORTANCE The cellular protease furin mediates proteolytic cleavage of many host and pathogen proteins and plays an important role in viral envelope glycoprotein maturation. MuV, an enveloped RNA virus of the Paramyxoviridae family and an important human pathogen, enters the cell through the fusion of its envelope with the plasma membrane of the target cell. Membrane fusion is mediated by the viral attachment protein and the F protein. Cleavage of MuV-F into two subunits by furin is a prerequisite for fusion and virus infectivity. Here, we show that LAMPs support the furin-mediated cleavage of MuV-F. Expression levels of LAMPs affect the processing of MuV-F and MuV-mediated membrane fusion. Among LAMPs, the interferon-stimulated gene product LAMP3 is most critical in certain cells. Our study provides potential targets for anti-MuV therapeutics.


2002 ◽  
Vol 76 (11) ◽  
pp. 5729-5736 ◽  
Author(s):  
Oliver Lung ◽  
Marcel Westenberg ◽  
Just M. Vlak ◽  
Douwe Zuidema ◽  
Gary W. Blissard

ABSTRACT GP64, the major envelope glycoprotein of budded virions of the baculovirus Autographa californica multicapsid nucleopolyhedrovirus (AcMNPV), is involved in viral attachment, mediates membrane fusion during virus entry, and is required for efficient virion budding. Thus, GP64 is essential for viral propagation in cell culture and in animals. Recent genome sequences from a number of baculoviruses show that only a subset of closely related baculoviruses have gp64 genes, while other baculoviruses have a recently discovered unrelated envelope protein named F. F proteins from Lymantria dispar MNPV (LdMNPV) and Spodoptera exigua MNPV (SeMNPV) mediate membrane fusion and are therefore thought to serve roles similar to that of GP64. To determine whether F proteins are functionally analogous to GP64 proteins, we deleted the gp64 gene from an AcMNPV bacmid and inserted F protein genes from three different baculoviruses. In addition, we also inserted envelope protein genes from vesicular stomatitis virus (VSV) and Thogoto virus. Transfection of the gp64-null bacmid DNA into Sf9 cells does not generate infectious particles, but this defect was rescued by introducing either the F protein gene from LdMNPV or SeMNPV or the G protein gene from VSV. These results demonstrate that baculovirus F proteins are functionally analogous to GP64. Because baculovirus F proteins appear to be more widespread within the family and are much more divergent than GP64 proteins, gp64 may represent the acquisition of an envelope protein gene by an ancestral baculovirus. The AcMNPV pseudotyping system provides an efficient and powerful method for examining the functions and compatibilities of analogous or orthologous viral envelope proteins, and it could have important biotechnological applications.


2021 ◽  
Vol 12 ◽  
Author(s):  
Kristina Schönfelder ◽  
Katharina Breuckmann ◽  
Carina Elsner ◽  
Ulf Dittmer ◽  
David Fistera ◽  
...  

The transmembrane serine protease 2 (TMPRSS2) is the major host protease that enables entry of the severe acute respiratory syndrome coronavirus type 2 (SARS-CoV-2) into host cells by spike (S) protein priming. Single nucleotide polymorphisms (SNPs) in the gene TMPRSS2 have been associated with susceptibility to and severity of H1N1 or H1N9 influenza A virus infections. Functional variants may influence SARS-CoV-2 infection risk and severity of Coronavirus disease 2019 (COVID-19) as well. Therefore, we analyzed the role of SNPs in the gene TMPRSS2 in a German case-control study. We performed genotyping of the SNPs rs2070788, rs383510, and rs12329760 in the gene TMPRSS2 in 239 SARS-CoV-2-positive and 253 SARS-CoV-2-negative patients. We analyzed the association of the SNPs with susceptibility to SARS-CoV-2 infection and severity of COVID-19. SARS-CoV-2-positive and SARS-CoV-2-negative patients did not differ regarding their demographics. The CC genotype of TMPRSS2 rs383510 was associated with a 1.73-fold increased SARS-CoV-2 infection risk, but was not correlated to severity of COVID-19. Neither TMPRSS2 rs2070788 nor rs12329760 polymorphisms were related to SARS-CoV-2 infection risk or severity of COVID-19. In a multivariable analysis (MVA), the rs383510 CC genotype remained an independent predictor for a 2-fold increased SARS-CoV-2 infection risk. In summary, our report appears to be the first showing that the intron variant rs383510 in the gene TMPRSS2 is associated with an increased risk to SARS-CoV-2 infection in a German cohort.


2011 ◽  
Vol 92 (10) ◽  
pp. 2333-2338 ◽  
Author(s):  
Sweety Samal ◽  
Sachin Kumar ◽  
Sunil K. Khattar ◽  
Siba K. Samal

A key determinant of Newcastle disease virus (NDV) virulence is the amino acid sequence at the fusion (F) protein cleavage site. The NDV F protein is synthesized as an inactive precursor, F0, and is activated by proteolytic cleavage between amino acids 116 and 117 to produce two disulfide-linked subunits, F1 and F2. The consensus sequence of the F protein cleavage site of virulent [112(R/K)-R-Q-(R/K)-R↓F-I118] and avirulent [112(G/E)-(K/R)-Q-(G/E)-R↓L-I118] strains contains a conserved glutamine residue at position 114. Recently, some NDV strains from Africa and Madagascar were isolated from healthy birds and have been reported to contain five basic residues (R-R-R-K-R↓F-I/V or R-R-R-R-R↓F-I/V) at the F protein cleavage site. In this study, we have evaluated the role of this conserved glutamine residue in the replication and pathogenicity of NDV by using the moderately pathogenic Beaudette C strain and by making Q114R, K115R and I118V mutants of the F protein in this strain. Our results showed that changing the glutamine to a basic arginine residue reduced viral replication and attenuated the pathogenicity of the virus in chickens. The pathogenicity was further reduced when the isoleucine at position 118 was substituted for valine.


2019 ◽  
Vol 94 (2) ◽  
Author(s):  
Marie Kubota ◽  
Iori Okabe ◽  
Shin-ichi Nakakita ◽  
Ayako Ueo ◽  
Yuta Shirogane ◽  
...  

ABSTRACT Mumps virus (MuV), an enveloped negative-strand RNA virus belonging to the family Paramyxoviridae, enters the host cell through membrane fusion mediated by two viral envelope proteins, an attachment protein hemagglutinin-neuraminidase (MuV-HN) and a fusion (F) protein. However, how the binding of MuV-HN to glycan receptors triggers membrane fusion is not well understood. The crystal structure of the MuV-HN head domain forms a tetramer (dimer of dimers) like other paramyxovirus attachment proteins. In the structure, a sulfate ion (SO42−) was found at the interface between two dimers, which may be replaced by a hydrogen phosphate ion (HPO42−) under physiological conditions. The anion is captured by the side chain of a positively charged arginine residue at position 139 of one monomer each from both dimers. Substitution of alanine or lysine for arginine at this position compromised the fusion support activity of MuV-HN without affecting its cell surface expression, glycan-receptor binding, and interaction with the F protein. Furthermore, the substitution appeared to affect the tetramer formation of the head domain as revealed by blue native-PAGE analysis. These results, together with our previous similar findings with the measles virus attachment protein head domain, suggest that the dimer-dimer interaction within the tetramer may play an important role in triggering membrane fusion during paramyxovirus entry. IMPORTANCE Despite the use of effective live vaccines, mumps outbreaks still occur worldwide. Mumps virus (MuV) infection typically causes flu-like symptoms and parotid gland swelling but sometimes leads to orchitis, oophoritis, and neurological complications, such as meningitis, encephalitis, and deafness. MuV enters the host cell through membrane fusion mediated by two viral proteins, a receptor-binding attachment protein, and a fusion protein, but its detailed mechanism is not fully understood. In this study, we show that the tetramer (dimer of dimers) formation of the MuV attachment protein head domain is supported by an anion located at the interface between two dimers and that the dimer-dimer interaction plays an important role in triggering the activation of the fusion protein and causing membrane fusion. These results not only further our understanding of MuV entry but provide useful information about a possible target for antiviral drugs.


Author(s):  
Stefan Bittmann

According to the latest research, the novel coronavirus uses the protein angiotensin-converting enzyme 2 (ACE-2) as a receptor for docking to the host cell. Essential for entry is the priming of the spike (S) protein of the virus by host cell proteases. A broadly based team led by infection biologists from the German Primate Centre and with the participation of the Charité Hospital in Berlin, the Hanover Veterinary University Foundation, the BG-UnfallklinikMurnau, the LMU Munich, the Robert Koch Institute and the German Centre for Infection Research wanted to find out how SARS-CoV-2 enters host cells and how this process can be blocked [1]. They have published their findings in the journal "Cell" [1]. The team of scientists was initially able to confirm that SARS-CoV-2 docks to the host cell via the ACE-2 receptor. They also identified Transmembrane serine protease 2 (TMPRSS2) as the cellular protein responsible for entry into the cell [1-3].


2007 ◽  
Vol 81 (7) ◽  
pp. 3130-3141 ◽  
Author(s):  
Laura E. Luque ◽  
Charles J. Russell

ABSTRACT During viral entry, the paramyxovirus fusion (F) protein fuses the viral envelope to a cellular membrane. Similar to other class I viral fusion glycoproteins, the F protein has two heptad repeat regions (HRA and HRB) that are important in membrane fusion and can be targeted by antiviral inhibitors. Upon activation of the F protein, HRA refolds from a spring-loaded, crumpled structure into a coiled coil that inserts a hydrophobic fusion peptide into the target membrane and binds to the HRB helices to form a fusogenic hairpin. To investigate how F protein conformational changes are regulated, we mutated in the Sendai virus F protein a highly conserved 10-residue sequence in HRA that undergoes major structural changes during protein refolding. Nine of the 15 mutations studied caused significant defects in F protein expression, processing, and fusogenicity. Conversely, the remaining six mutations enhanced the fusogenicity of the F protein, most likely by helping spring the HRA coil. Two of the residues that were neither located at “a” or “d” positions in the heptad repeat nor conserved among the paramyxoviruses were key regulators of the folding and fusion activity of the F protein, showing that residues not expected to be important in coiled-coil formation may play important roles in regulating membrane fusion. Overall, the data support the hypothesis that regions in the F protein that undergo dramatic changes in secondary and tertiary structure between the prefusion and hairpin conformations regulate F protein expression and activation.


2020 ◽  
Vol 245 (5) ◽  
pp. 477-485
Author(s):  
Chaozai Zhang ◽  
Ruohan Zhu ◽  
Qizhi Cao ◽  
Xiaohong Yang ◽  
Ziwei Huang ◽  
...  

The chemokine receptor CXCR4 is required for the entry of human immunodeficiency virus type 1 (HIV-1) into target cells and its expression correlates with more profound pathogenicity, rapid progression to acquired immunodeficiency syndrome (AIDS), and greater AIDS-related mortality. There is still no cure for AIDS and no method for preventing or eradicating HIV-1 infection. HIV-1 entry begins with the interaction of the viral envelope glycoprotein gp120 and the primary receptor CD4, and subsequently with the coreceptors, CCR5 or CXCR4, on the host cells. Blocking the interaction of HIV-1 and its coreceptors is therefore a promising strategy for developing new HIV-1 entry inhibitors. This approach has a dual benefit, as it prevents HIV-1 infection and progression while also targeting the reservoirs of HIV-1 infected, coreceptor positive macrophages and memory T cells. To date, multiple classes of CXCR4-targeted anti-HIV-1 inhibitors have been discovered and are now at different preclinical and clinical stages. In this review, we highlight the studies of CXCR4-targeted small-molecule and peptide HIV-1 entry inhibitors discovered during the last two decades and provide a reference for further potential HIV-1 exploration in the future. Impact statement This minireview summarized the current progress in the identification of CXCR4-targeted HIV-1-entry inhibitors based on discovery/developmental approaches. It also provided a discussion of the inhibitor structural features, antiviral activities, and pharmacological properties. Unlike other reviews on anti-HIV-1 drug development, which have generally emphasized inhibitors that target intracellular viral replication and host genomic integration, this review focused on the drug discovery approaches taken to develop viral-entry inhibitors aimed at disturbing the initial step of viral interaction with uninfected host cells and preventing the subsequent viral replication/genomic integration. This review amalgamated recently published and important work on bivalent CXCR4-targeted anti-HIV-1-entry candidates/conjugates, discussed the research challenges faced in developing drugs to prevent and eradicate HIV-1 infection, and provided a perspective on strategies that can lead to future drug discoveries. The findings and strategies summarized in this review will be of interest to investigators throughout the microbiological, pharmaceutical, and translational research communities.


2016 ◽  
Vol 90 (23) ◽  
pp. 10762-10773 ◽  
Author(s):  
Jacquelyn A. Stone ◽  
Bhadra M. Vemulapati ◽  
Birgit Bradel-Tretheway ◽  
Hector C. Aguilar

ABSTRACTThe paramyxoviral family contains many medically important viruses, including measles virus, mumps virus, parainfluenza viruses, respiratory syncytial virus, human metapneumovirus, and the deadly zoonotic henipaviruses Hendra and Nipah virus (NiV). To both enter host cells and spread from cell to cell within infected hosts, the vast majority of paramyxoviruses utilize two viral envelope glycoproteins: the attachment glycoprotein (G, H, or hemagglutinin-neuraminidase [HN]) and the fusion glycoprotein (F). Binding of G/H/HN to a host cell receptor triggers structural changes in G/H/HN that in turn trigger F to undergo a series of conformational changes that result in virus-cell (viral entry) or cell-cell (syncytium formation) membrane fusion. The actual regions of G/H/HN and F that interact during the membrane fusion process remain relatively unknown though it is generally thought that the paramyxoviral G/H/HN stalk region interacts with the F head region. Studies to determine such interactive regions have relied heavily on coimmunoprecipitation approaches, whose limitations include the use of detergents and the micelle-mediated association of proteins. Here, we developed a flow-cytometric strategy capable of detecting membrane protein-protein interactions by interchangeably using the full-length form of G and a soluble form of F, or vice versa. Using both coimmunoprecipitation and flow-cytometric strategies, we found a bidentate interaction between NiV G and F, where both the stalk and head regions of NiV G interact with F. This is a new structural-biological finding for the paramyxoviruses. Additionally, our studies disclosed regions of the NiV G and F glycoproteins dispensable for the G and F interactions.IMPORTANCENipah virus (NiV) is a zoonotic paramyxovirus that causes high mortality rates in humans, with no approved treatment or vaccine available for human use. Viral entry into host cells relies on two viral envelope glycoproteins: the attachment (G) and fusion (F) glycoproteins. Binding of G to the ephrinB2 or ephrinB3 cell receptors triggers conformational changes in G that in turn cause F to undergo conformational changes that result in virus-host cell membrane fusion and viral entry. It is currently unknown, however, which specific regions of G and F interact during membrane fusion. Past efforts to determine the interacting regions have relied mainly on coimmunoprecipitation, a technique with some pitfalls. We developed a flow-cytometric assay to study membrane protein-protein interactions, and using this assay we report a bidentate interaction whereby both the head and stalk regions of NiV G interact with NiV F, a new finding for the paramyxovirus family.


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