Hemagglutinin-neuraminidase enhances F protein-mediated membrane fusion of reconstituted Sendai virus envelopes with cells.

1993 ◽  
Vol 67 (6) ◽  
pp. 3312-3318 ◽  
Author(s):  
S Bagai ◽  
A Puri ◽  
R Blumenthal ◽  
D P Sarkar
Keyword(s):  
Membrane Fusion ◽  
Sendai Virus ◽  
F Protein

scholarly journals Residues in the Heptad Repeat A Region of the Fusion Protein Modulate the Virulence of Sendai Virus in Mice

2009 ◽  
Vol 84 (2) ◽  
pp. 810-821 ◽  
Author(s):  
Laura E. Luque ◽  
Olga A. Bridges ◽  
John N. Mason ◽  
Kelli L. Boyd ◽  
Allen Portner ◽  
...  
Keyword(s):  
Membrane Fusion ◽  
Sendai Virus ◽  
Syncytium Formation ◽  
Heptad Repeat ◽  
Wild Type Virus ◽  
Type Virus ◽  
Wild Type ◽  
F Protein

ABSTRACT While the molecular basis of fusion (F) protein refolding during membrane fusion has been studied extensively in vitro, little is known about the biological significance of membrane fusion activity in parainfluenza virus replication and pathogenesis in vivo. Two recombinant Sendai viruses, F-L179V and F-K180Q, were generated that contain F protein mutations in the heptad repeat A region of the ectodomain, a region of the protein known to regulate F protein activation. In vitro, the F-L179V virus caused increased syncytium formation (cell-cell membrane fusion) yet had a rate of replication and levels of F protein expression and cleavage similar to wild-type virus. The F-K180Q virus had a reduced replication rate along with reduced levels of F protein expression, cleavage, and fusogenicity. In DBA/2 mice, the hyperfusogenic F-L179V virus induced greater morbidity and mortality than wild-type virus, while the attenuated F-K180Q virus was much less pathogenic. During the first week of infection, virus replication and inflammation in the lungs were similar for wild-type and F-L179V viruses. After approximately 1 week of infection, the clearance of F-L179V virus was delayed, and more extensive interstitial inflammation and necrosis were observed in the lungs, affecting entire lobes of the lungs and having significantly greater numbers of syncytial cell masses in alveolar spaces on day 10. On the other hand, the slower-growing F-K180Q virus caused much less extensive inflammation than wild-type virus, presumably due to its reduced replication rate, and did not cause observable syncytium formation in the lungs. Overall, the results show that residues in the heptad repeat A region of the F protein modulate the virulence of Sendai virus in mice by influencing both the spread and clearance of the virus and the extent and severity of inflammation. An understanding of how the F protein contributes to infection and inflammation in vivo may assist in the development of antiviral therapies against respiratory paramyxoviruses.

scholarly journals Spring-Loaded Heptad Repeat Residues Regulate the Expression and Activation of Paramyxovirus Fusion Protein

2007 ◽  
Vol 81 (7) ◽  
pp. 3130-3141 ◽  
Author(s):  
Laura E. Luque ◽  
Charles J. Russell
Keyword(s):  
Protein Expression ◽  
Membrane Fusion ◽  
Conformational Changes ◽  
Structural Changes ◽  
Tertiary Structure ◽  
Sendai Virus ◽  
Coiled Coil ◽  
Viral Envelope ◽  
Heptad Repeat ◽  
F Protein

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.

scholarly journals Insertion of the Two Cleavage Sites of the Respiratory Syncytial Virus Fusion Protein in Sendai Virus Fusion Protein Leads to Enhanced Cell-Cell Fusion and a Decreased Dependency on the HN Attachment Protein for Activity

2008 ◽  
Vol 82 (12) ◽  
pp. 5986-5998 ◽  
Author(s):  
Joanna Rawling ◽  
Blanca García-Barreno ◽  
José A. Melero
Keyword(s):  
Respiratory Syncytial Virus ◽  
Fusion Protein ◽  
Membrane Fusion ◽  
Cell Fusion ◽  
Sendai Virus ◽  
Cleavage Sites ◽  
Attachment Protein ◽  
F Protein ◽  
Syncytial Virus ◽  
Cell Cell

ABSTRACT Cell entry by paramyxoviruses requires fusion of the viral envelope with the target cell membrane. Fusion is mediated by the viral fusion (F) glycoprotein and usually requires the aid of the attachment glycoprotein (G, H or HN, depending on the virus). Human respiratory syncytial virus F protein (FRSV) is able to mediate membrane fusion in the absence of the attachment G protein and is unique in possessing two multibasic furin cleavage sites, separated by a region of 27 amino acids (pep27). Cleavage at both sites is required for cell-cell fusion. We have investigated the significance of the two cleavage sites and pep27 in the context of Sendai virus F protein (FSeV), which possesses a single monobasic cleavage site and requires both coexpression of the HN attachment protein and trypsin in order to fuse cells. Inclusion of both FRSV cleavage sites in FSeV resulted in a dramatic increase in cell-cell fusion activity in the presence of HN. Furthermore, chimeric FSeV mutants containing both FRSV cleavage sites demonstrated cell-cell fusion in the absence of HN. The presence of two multibasic cleavage sites may therefore represent a strategy to regulate activation of a paramyxovirus F protein for cell-cell fusion in the absence of an attachment protein.

scholarly journals A Functional F Analogue of Autographa californica Nucleopolyhedrovirus GP64 from the Agrotis segetum Granulovirus

2008 ◽  
Vol 82 (17) ◽  
pp. 8922-8926 ◽  
Author(s):  
Feifei Yin ◽  
Manli Wang ◽  
Ying Tan ◽  
Fei Deng ◽  
Just M. Vlak ◽  
...  
Keyword(s):  
Fusion Protein ◽  
Membrane Fusion ◽  
Plutella Xylostella ◽  
Syncytium Formation ◽  
Low Ph ◽  
Autographa Californica ◽  
Agrotis Segetum ◽  
Induced Membrane ◽  
F Protein ◽  
Autographa Californica Nucleopolyhedrovirus

ABSTRACT The envelope fusion protein F of Plutella xylostella granulovirus is a computational analogue of the GP64 envelope fusion protein of Autographa californica nucleopolyhedrovirus (AcMNPV). Granulovirus (GV) F proteins were thought to be unable to functionally replace GP64 in the AcMNPV pseudotyping system. In the present study the F protein of Agrotis segetum GV (AgseGV) was identified experimentally as the first functional GP64 analogue from GVs. AgseF can rescue virion propagation and infectivity of gp64-null AcMNPV. The AgseF-pseudotyped AcMNPV also induced syncytium formation as a consequence of low-pH-induced membrane fusion.

scholarly journals Sendai virus recruits cellular villin to remodel actin cytoskeleton during fusion with hepatocytes

2017 ◽  
Vol 28 (26) ◽  
pp. 3801-3814 ◽  
Author(s):  
Sunandini Chandra ◽  
Raju Kalaivani ◽  
Manoj Kumar ◽  
Narayanaswamy Srinivasan ◽  
Debi P. Sarkar
Keyword(s):  
Membrane Fusion ◽  
Viral Entry ◽  
Sendai Virus ◽  
Viral Envelope ◽  
Bioactive Molecules ◽  
Host Cells ◽  
Actin Dynamics ◽  
Envelope Glycoproteins ◽  
Animal Cells ◽  
Viral Envelopes

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.

Short-stalk isoforms of CADM1 and CADM2 trigger neuropathogenic measles virus-mediated membrane fusion by interacting with the viral hemagglutinin

2021 ◽  
Author(s):  
Ryuichi Takemoto ◽  
Tateki Suzuki ◽  
Takao Hashiguchi ◽  
Yusuke Yanagi ◽  
Yuta Shirogane
Keyword(s):  
Cell Membrane ◽  
Membrane Fusion ◽  
Measles Virus ◽  
Subacute Sclerosing Panencephalitis ◽  
Febrile Illness ◽  
Host Factors ◽  
F Protein ◽  
Short Stalk ◽  
Head Domain ◽  
H Protein

Measles virus (MeV), an enveloped RNA virus in the family Paramyxoviridae , usually causes acute febrile illness with skin rash, but in rare cases persists in the brain, causing a progressive neurological disorder, subacute sclerosing panencephalitis (SSPE). MeV bears two envelope glycoproteins, the hemagglutinin (H) and fusion (F) proteins. The H protein possesses a head domain that initially mediates receptor binding and a stalk domain that subsequently transmits the fusion-triggering signal to the F protein. We have recently shown that cell adhesion molecule 1 (CADM1, also known as IGSF4A, Necl-2, SynCAM1) and CADM2 (also known as IGSF4D, Necl-3, SynCAM2) are host factors enabling cell-cell membrane fusion mediated by hyperfusogenic F proteins of neuropathogenic MeVs as well as MeV spread between neurons lacking the known receptors. CADM1 and CADM2 interact in cis with the H protein on the same cell membrane, triggering hyperfusogenic F protein-mediated membrane fusion. Multiple isoforms of CADM1 and CADM2 containing various lengths of their stalk regions are generated by alternative splicing. Here we show that only short-stalk isoforms of CADM1 and CADM2 predominantly expressed in the brain induce hyperfusogenic F protein-mediated membrane fusion. While the known receptors interact in trans with the H protein through its head domain, these isoforms can interact in cis even with the H protein lacking the head domain and trigger membrane fusion, presumably through its stalk domain. Thus, our results unveil a new mechanism of viral fusion triggering by host factors. Importance Measles, an acute febrile illness with skin rash, is still an important cause of childhood morbidity and mortality worldwide. Measles virus (MeV), the causative agent of measles, may also cause a progressive neurological disorder, subacute sclerosing panencephalitis (SSPE), several years after acute infection. The disease is fatal, and no effective therapy is available. Recently, we have reported that cell adhesion molecule 1 (CADM1) and CADM2 are host factors enabling MeV cell-to-cell spread in neurons. These molecules interact in cis with the MeV attachment protein on the same cell membrane, triggering the fusion protein and causing membrane fusion. CADM1 and CADM2 are known to exist in multiple splice isoforms. In this study, we report that their short-stalk isoforms can induce membrane fusion by interacting in cis with the viral attachment protein independently of its receptor-binding head domain. This finding may have important implications for cis -acting fusion triggering by host factors.

Studies of membrane fusion. VI. Mechanism of the membrane fusion and cell swelling stages of Sendai virus-mediated cell fusion

1980 ◽  
Vol 43 (1) ◽  
pp. 103-118
Author(s):  
S. Knutton
Keyword(s):  
Membrane Fusion ◽  
Cell Fusion ◽  
Sendai Virus ◽  
Freeze Fracture ◽  
Viral Envelope ◽  
Cell Swelling ◽  
Fusion Event ◽  
Virus Envelope ◽  
Membrane Rupture ◽  
Membrane Tubules

The membrane fusion and cell swelling stages of Sendai virus-mediated cell-cell fusion have been studied by thin-section and freeze-fracture electron microscopy. Sites of membrane fusion have been detected in human erythrocytes arrested at the membrane fusion stage of cell fusion and in virtually all cases a fused viral envelope or envelope components has been identified thus providing further direct evidence that cell-viral envelope-cell bridge formation is the membrane fusion event in Sendai virus-induced cell fusion. Radial expansion of a single virus bridge connecting 2 cells is sufficient to produce a fused cell. Membrane redistribution which occurs during this cell swelling stage of the fusion process is often accompanied by the formation of a system of membrane tubules in the plane of expansion of the virus bridge. The tubules originate from points of fusion between the bridging virus envelope and the erythrocyte membrane and also expand radially as cells swell. Ultimately membrane rupture occurs and the tubules appear to break down as small vesicles. When previously observed in cross-sectioned cells these membrane tubules were interpreted as sites of direct membrane fusion. The present study indicates that this interpretation is incorrect and shows that the tubules are generated subsequent to membrane fusion when 2 cells connected by a virus bridge are induced to swell. A mechanism to explain the formation of this system of membrane tubules is proposed.

Studies of membrane fusion. V. Fusion of erythrocytes with non-haemolytic Sendai virus

1979 ◽  
Vol 36 (1) ◽  
pp. 85-96
Author(s):  
S. Knutton
Keyword(s):  
Membrane Fusion ◽  
Cell Fusion ◽  
Erythrocyte Membrane ◽  
Sendai Virus ◽  
Lateral Diffusion ◽  
Viral Envelope ◽  
Cell Swelling ◽  
Viral Membrane ◽  
Cytoplasmic Bridges ◽  
Viral Envelopes

The fusion of human erythrocytes with non-haemolytic ‘1-day’ Sendai virus has been studied by electron microscopy. The mechanism of viral envelope-cell fusion is the same as that described previously for haemolytic ‘3-day’ Sendai virus except that fusion is frequently arrested at an initial stage when 2 segments of smooth linear viral membrane fuse and become incorporated into the erythrocyte membrane. After longer periods of incubation at 37 degrees C, in addition to many partly fused virus particles, long (up to 4 micrometer) lengths of smooth linear viral membrane are seen within the erythrocyte membrane which arise by linear aggregation of shorter (approximately 0.25 micrometer long) segments of smooth linear membrane derived from individual fused viral envelopes. Cell-Cell fusion, as a result of the fusion of a viral envelope with 2 adjacent erythrocytes also occurs but, in the absence of cell swelling, fusion is arrested at this stage with cells joined by one (or more) small cytoplasmic bridges. Typical fused cells are produced if such cells are swollen with hypotonic buffer. These observations provide further evidence that membrane fusion and cell swelling are distinct events in cell fusion and that cell swelling is the driving force both for completing the incorporation of the viral envelope into the cell membrane and for expanding cells connected by small cytoplasmic bridges to form spherical fused cells. Little lateral diffusion of viral envelope components occurs in the absence of cell swelling; in fact, some aggregation of components occurs. Comparison with previous studies using haemolytic ‘3-day’ Sendai virus suggests that virally induced cell swelling perturbs membrane structure so as to allow the rapid lateral diffusion of integrated viral envelope components.

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