scholarly journals A New Class of Receptor for Herpes Simplex Virus Has Heptad Repeat Motifs That Are Common to Membrane Fusion Proteins

2005 ◽  
Vol 79 (12) ◽  
pp. 7419-7430 ◽  
Author(s):  
Aleida Perez ◽  
Qing-Xue Li ◽  
Pilar Perez-Romero ◽  
Gregory DeLassus ◽  
Santiago R. Lopez ◽  
...  
Keyword(s):  
Herpes Simplex Virus ◽  
Herpes Simplex ◽  
Membrane Fusion ◽  
Fusion Proteins ◽  
Surface Membrane ◽  
Heptad Repeat ◽  
Expression Cloning ◽  
Viral Fusion ◽  
Α Helix ◽  
Simplex Virus

ABSTRACT We isolated a human cDNA by expression cloning and characterized its gene product as a new human protein that enables entry and infection of herpes simplex virus (HSV). The gene, designated hfl-B5, encodes a type II cell surface membrane protein, B5, that is broadly expressed in human primary tissue and cell lines. It contains a high-scoring heptad repeat at the extracellular C terminus that is predicted to form an α-helix for coiled coils like those in cellular SNAREs or in some viral fusion proteins. A synthetic 30-mer peptide that has the same sequence as the heptad repeat α-helix blocks HSV infection of B5-expressing porcine cells and human HEp-2 cells. Transient expression of human B5 in HEp-2 cells results in increased polykarocyte formation even in the absence of viral proteins. The B5 protein fulfills all criteria as a receptor or coreceptor for HSV entry. Use by HSV of a human cellular receptor, such as B5, that contains putative membrane fusion domains provides an example where a pathogenic virus with broad tropism has usurped a widely expressed cellular protein to function in infection at events that lead to membrane fusion.

scholarly journals Reevaluating Herpes Simplex Virus Hemifusion

2010 ◽  
Vol 84 (22) ◽  
pp. 11814-11821 ◽  
Author(s):  
Julia O. Jackson ◽  
Richard Longnecker
Keyword(s):  
Herpes Simplex Virus ◽  
Herpes Simplex ◽  
Fusion Protein ◽  
Membrane Fusion ◽  
Fusion Proteins ◽  
Fusion Pore ◽  
Viral Fusion ◽  
Viral Fusion Protein ◽  
Viral Fusion Proteins ◽  
Simplex Virus

ABSTRACT Membrane fusion induced by enveloped viruses proceeds through the actions of viral fusion proteins. Once activated, viral fusion proteins undergo large protein conformational changes to execute membrane fusion. Fusion is thought to proceed through a “hemifusion” intermediate in which the outer membrane leaflets of target and viral membranes mix (lipid mixing) prior to fusion pore formation, enlargement, and completion of fusion. Herpes simplex virus type 1 (HSV-1) requires four glycoproteins—glycoprotein D (gD), glycoprotein B (gB), and a heterodimer of glycoprotein H and L (gH/gL)—to accomplish fusion. gD is primarily thought of as a receptor-binding protein and gB as a fusion protein. The role of gH/gL in fusion has remained enigmatic. Despite experimental evidence that gH/gL may be a fusion protein capable of inducing hemifusion in the absence of gB, the recently solved crystal structure of HSV-2 gH/gL has no structural homology to any known viral fusion protein. We found that in our hands, all HSV entry proteins—gD, gB, and gH/gL—were required to observe lipid mixing in both cell-cell- and virus-cell-based hemifusion assays. To verify that our hemifusion assay was capable of detecting hemifusion, we used glycosylphosphatidylinositol (GPI)-linked hemagglutinin (HA), a variant of the influenza virus fusion protein, HA, known to stall the fusion process before productive fusion pores are formed. Additionally, we found that a mutant carrying an insertion within the short gH cytoplasmic tail, 824L gH, is incapable of executing hemifusion despite normal cell surface expression. Collectively, our findings suggest that HSV gH/gL may not function as a fusion protein and that all HSV entry glycoproteins are required for both hemifusion and fusion. The previously described gH 824L mutation blocks gH/gL function prior to HSV-induced lipid mixing.

scholarly journals A Heptad Repeat in Herpes Simplex Virus 1 gH, Located Downstream of the α-Helix with Attributes of a Fusion Peptide, Is Critical for Virus Entry and Fusion

2005 ◽  
Vol 79 (11) ◽  
pp. 7042-7049 ◽  
Author(s):  
Tatiana Gianni ◽  
Laura Menotti ◽  
Gabriella Campadelli-Fiume
Keyword(s):  
Herpes Simplex Virus ◽  
Herpes Simplex ◽  
Virus Entry ◽  
Coiled Coil ◽  
Fusion Peptide ◽  
Heptad Repeat ◽  
Herpes Simplex Virus 1 ◽  
Α Helix ◽  
Simplex Virus ◽  
Hsv 1

ABSTRACT Entry of herpes simplex virus 1 (HSV-1) into cells occurs by fusion with cell membranes; it requires gD as the receptor binding glycoprotein and the trigger of fusion, and the trio of the conserved glycoproteins gB, gH, and gL to execute fusion. Recently, we reported that the ectodomain of HSV-1 gH carries a hydrophobic α-helix (residues 377 to 397) with attributes of an internal fusion peptide (T. Gianni, P. L. Martelli, R. Casadio, and G. Campadelli-Fiume, J. Virol. 79:2931-2940, 2005). Downstream of this α-helix, a heptad repeat (HR) with a high propensity to form a coiled coil was predicted between residues 443 and 471 and was designated HR-1. The simultaneous substitution of two amino acids in HR-1 (E450G and L453A), predicted to abolish the coiled coil, abolished the ability of gH to complement the infectivity of a gH-null HSV mutant. When coexpressed with gB, gD, and gL, the mutant gH was unable to promote cell-cell fusion. These defects were not attributed to a defect in heterodimer formation with gL, the gH chaperone, or in trafficking to the plasma membrane. A 25-amino-acid synthetic peptide with the sequence of HR-1 (pep-gHwt25) inhibited HSV replication if present at the time of virus entry into the cell. A scrambled peptide had no effect. The effect was specific, as pep-gHwt25 did not reduce HSV-2 and pseudorabies virus infection. The presence of a functional HR in the HSV-1 gH ectodomain strengthens the view that gH has attributes typical of a viral fusion glycoprotein.

scholarly journals Nuclear envelope breakdown induced by herpes simplex virus type 1 involves the activity of viral fusion proteins

Virology ◽  
2014 ◽  
Vol 460-461 ◽  
pp. 128-137 ◽  
Author(s):  
Martina Maric ◽  
Alison C. Haugo ◽  
William Dauer ◽  
David Johnson ◽  
Richard J. Roller
Keyword(s):  
Herpes Simplex Virus ◽  
Herpes Simplex ◽  
Nuclear Envelope ◽  
Herpes Simplex Virus Type ◽  
Fusion Proteins ◽  
Viral Fusion ◽  
Nuclear Envelope Breakdown ◽  
Viral Fusion Proteins ◽  
Simplex Virus

scholarly journals Extended Synaptotagmin 1 Interacts with Herpes Simplex Virus 1 Glycoprotein M and Negatively Modulates Virus-Induced Membrane Fusion

2017 ◽  
Vol 92 (1) ◽  
Author(s):  
Imane El Kasmi ◽  
Bita Khadivjam ◽  
Miki Lackman ◽  
Johanne Duron ◽  
Eric Bonneil ◽  
...  
Keyword(s):  
Herpes Simplex Virus ◽  
Herpes Simplex ◽  
Membrane Fusion ◽  
Viral Proteins ◽  
Life Cycles ◽  
Viral Fusion ◽  
Herpes Simplex Virus 1 ◽  
Synaptotagmin 1 ◽  
Simplex Virus ◽  
Hsv 1

ABSTRACTEnveloped viruses typically encode their own fusion machinery to enter cells. Herpesviruses are unusual, as they fuse with a number of cellular compartments throughout their life cycles. As uncontrolled fusion of the host membranes should be avoided in these events, tight regulation of the viral fusion machinery is critical. While studying herpes simplex virus 1 (HSV-1) glycoprotein gM, we identified the cellular protein E-Syt1 (extended synaptotagmin 1) as an interaction partner. The interaction took place in both infected and transfected cells, suggesting other viral proteins were not required for the interaction. Most interestingly, E-Syt1 is a member of the synaptotagmin family of membrane fusion regulators. However, the protein is known to promote the tethering of the endoplasmic reticulum (ER) to the plasma membrane. We now show that E-Syt1, along with the related E-Syt3, negatively modulates viral release into the extracellular milieu, cell-to-cell viral spread, and viral entry, all processes that implicate membrane fusion events. Similarly, these E-Syt proteins impacted the formation of virus-induced syncytia. Altogether, these findings hint at the modulation of the viral fusion machinery by the E-Syt family of proteins.IMPORTANCEViruses typically encode their own fusion apparatus to enable them to enter cells. For many viruses, this means a single fusogenic protein. However, herpesviruses are large entities that express several accessory viral proteins to regulate their fusogenic activity. The present study hints at the additional participation of cellular proteins in this process, suggesting the host can also modulate viral fusion to some extent. Hence E-Syt proteins 1 and 3 seem to negatively modulate the different viral fusion events that take place during the HSV-1 life cycle. This could represent yet another innate immunity response to the virus.

scholarly journals Heptad Repeat 2 in Herpes Simplex Virus 1 gH Interacts with Heptad Repeat 1 and Is Critical for Virus Entry and Fusion

2006 ◽  
Vol 80 (5) ◽  
pp. 2216-2224 ◽  
Author(s):  
Tatiana Gianni ◽  
Angela Piccoli ◽  
Carlo Bertucci ◽  
Gabriella Campadelli-Fiume
Keyword(s):  
Circular Dichroism ◽  
Herpes Simplex Virus ◽  
Herpes Simplex ◽  
Coiled Coil ◽  
Heptad Repeat ◽  
Herpes Simplex Virus 1 ◽  
Mimetic Peptides ◽  
Simplex Virus ◽  
Circular Dichroïsm ◽  
Hsv 1

ABSTRACT Herpes simplex virus 1 (HSV-1) entry into cells and cell-cell fusion mediated by HSV-1 glycoproteins require four glycoproteins, gD, gB, gH, gL. Of these, gH is the only one that so far exhibits structural-functional features typical of viral fusion glycoproteins, i.e., a candidate fusion peptide and, downstream of it, a heptad repeat (HR) segment able to form a coiled coil, named HR-1. Here, we show that gH carries a functional HR-2 capable of physical interaction with HR-1. Specifically, mutational analysis of gH aimed at increasing or decreasing the ability of HR-2 to form a coiled coil resulted in an increase or decrease of fusion activity, respectively. HSV infection was modified accordingly. A mimetic peptide with the HR-2 sequence inhibited HSV-1 infection in a specific and dose-dependent manner. Circular dichroism spectroscopy showed that both HR-2 and HR-1 mimetic peptides adopt mainly random conformation in aqueous solution, while a decrease in peptide environmental polarity determines a conformational change, with a significant increase of the α-helical conformation content, in particular, for the HR-1 peptide. Furthermore, HR-1 and HR-2 mimetic peptides formed a stable complex, as revealed in nondenaturing electrophoresis and by circular dichroism. The mixture of HR-1 and HR-2 peptides reversed the inhibition of HSV infection exerted by the single peptides. Complex formation between HR-1 and HR-2 was independent of the presence of adjacent gH sequences and of additional glycoproteins involved in entry and fusion. Altogether, HR-2 adds to the features typical of class 1 fusion glycoproteins exhibited by HSV-1 gH.

scholarly journals Insertional Mutations in Herpes Simplex Virus Type 1 gL Identify Functional Domains for Association with gH and for Membrane Fusion

2009 ◽  
Vol 83 (22) ◽  
pp. 11607-11615 ◽  
Author(s):  
Qing Fan ◽  
Erick Lin ◽  
Patricia G. Spear
Keyword(s):  
Herpes Simplex Virus ◽  
Herpes Simplex ◽  
Cell Surface ◽  
Membrane Fusion ◽  
Cell Fusion ◽  
Viral Entry ◽  
Cell Surface Receptor ◽  
Cell Surface Expression ◽  
Conserved Domain ◽  
Simplex Virus

ABSTRACT Glycoprotein L (gL) is one of four glycoproteins required for the entry of herpes simplex virus (HSV) into cells and for virus-induced cell fusion. This glycoprotein oligomerizes with gH to form a membrane-bound heterodimer but can be secreted when expressed without gH. Twelve unique gL linker-insertion mutants were generated to identify regions critical for gH binding and gH/gL processing and regions essential for cell fusion and viral entry. All gL mutants were detected on the cell surface in the absence of gH, suggesting incomplete cleavage of the signal peptide or the presence of a cell surface receptor for secreted gL. Coexpression with gH enhanced the levels of cell surface gL detected by antibodies for all gL mutants except those that were defective in their interactions with gH. Two insertions into a conserved region of gL abrogated the binding of gL to gH and prevented gH expression on the cell surface. Three other insertions reduced the cell surface expression of gH and/or altered the properties of gH/gL heterodimers. Altered or absent interaction of gL with gH was correlated with reduced or absent cell fusion activity and impaired complementation of virion infectivity. These results identify a conserved domain of gL that is critical for its binding to gH and two noncontiguous regions of gL, one of which contains the conserved domain, that are critical for the gH/gL complex to perform its role in membrane fusion.

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