scholarly journals Endoplasmic Reticulum Detergent-Resistant Membranes Accommodate Hepatitis C Virus Proteins for Viral Assembly

Cells ◽  
2019 ◽  
Vol 8 (5) ◽  
pp. 487 ◽  
Author(s):  
Audrey Boyer ◽  
Julie Dreneau ◽  
Amélie Dumans ◽  
Julien Burlaud-Gaillard ◽  
Anne Bull-Maurer ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Hepatitis C Virus ◽  
Hepatitis C ◽  
Protein Interactions ◽  
Gradient Centrifugation ◽  
Cellular Membrane ◽  
Structural Protein ◽  
Membrane Structures ◽  
Detergent Resistant Membranes ◽  
Lysis Buffer

During Hepatitis C virus (HCV) morphogenesis, the non-structural protein 2 (NS2) brings the envelope proteins 1 and 2 (E1, E2), NS3, and NS5A together to form a complex at the endoplasmic reticulum (ER) membrane, initiating HCV assembly. The nature of the interactions in this complex is unclear, but replication complex and structural proteins have been shown to be associated with cellular membrane structures called detergent-resistant membranes (DRMs). We investigated the role of DRMs in NS2 complex formation, using a lysis buffer combining Triton and n-octyl glucoside, which solubilized both cell membranes and DRMs. When this lysis buffer was used on HCV-infected cells and the resulting lysates were subjected to flotation gradient centrifugation, all viral proteins and DRM-resident proteins were found in soluble protein fractions. Immunoprecipitation assays demonstrated direct protein–protein interactions between NS2 and E2 and E1 proteins, and an association of NS2 with NS3 through DRMs. The well-folded E1E2 complex and NS5A were not associated, instead interacting separately with the NS2-E1-E2-NS3 complex through less stable DRMs. Core was also associated with NS2 and the E1E2 complex through these unstable DRMs. We suggest that DRMs carrying this NS2-E1-E2-NS3-4A-NS5A-core complex may play a central role in HCV assembly initiation, potentially as an assembly platform.

scholarly journals Protein-Protein Interactions between Hepatitis C Virus Nonstructural Proteins

2003 ◽  
Vol 77 (9) ◽  
pp. 5401-5414 ◽  
Author(s):  
Maria Dimitrova ◽  
Isabelle Imbert ◽  
Marie Paule Kieny ◽  
Catherine Schuster
Keyword(s):  
Endoplasmic Reticulum ◽  
Hepatitis C Virus ◽  
Hepatitis C ◽  
Protein Interactions ◽  
Laser Scanning ◽  
Ex Vivo ◽  
Laser Scanning Microscopy ◽  
Confocal Laser ◽  
Nonstructural Proteins

ABSTRACT Replication of the hepatitis C virus (HCV) genome has been proposed to take place close to the membrane of the endoplasmic reticulum in membrane-associated replicase complexes, as is the case with several other plus-strand RNA viruses, such as poliovirus and flaviviruses. The most obvious benefits of this property are the possibility of coupling functions residing in different polypeptidic chains and the sequestration of viral proteins and nucleic acids in a distinct cytoplasmic compartment with high local concentrations of viral components. Indeed, HCV nonstructural (NS) proteins were clearly colocalized in association with membranes derived from the endoplasmic reticulum. This observation, together with the demonstration of the existence of several physical interactions between HCV NS proteins, supports the idea of assembly of a highly ordered multisubunit protein complex(es) probably involved in the replication of the viral genome. The objective of this study, therefore, was to examine all potential interactions between HCV NS proteins which could result in the formation of a replication complex(es). We identified several interacting viral partners by using a glutathione S-transferase pull-down assay, by in vitro and ex vivo coimmunoprecipitation experiments in adenovirus-infected Huh-7 cells allowing the expression of HCV NS proteins, and, finally, by using the yeast two-hybrid system. In addition, by confocal laser scanning microscopy, NS proteins were clearly shown to colocalize when expressed together in Huh-7 cells. We have been able to demonstrate the existence of a complex network of interactions implicating all six NS proteins. Our observations confirm previously described associations and identify several novel homo- and heterodimerizations.

scholarly journals Mobility of the hepatitis C virus NS4B protein on the endoplasmic reticulum membrane and membrane-associated foci

2005 ◽  
Vol 86 (5) ◽  
pp. 1415-1421 ◽  
Author(s):  
Sarah N. Gretton ◽  
Annette I. Taylor ◽  
John McLauchlan
Keyword(s):  
Endoplasmic Reticulum ◽  
Hepatitis C Virus ◽  
Hepatitis C ◽  
Morphological Changes ◽  
Hcv Rna ◽  
Endoplasmic Reticulum Membrane ◽  
Structural Protein ◽  
Direct Role ◽  
Cellular Marker ◽  
Er Membrane

The hepatitis C virus (HCV) non-structural protein NS4B induces morphological changes in the endoplasmic reticulum (ER) membrane that may have a direct role in viral RNA replication. A chimeric GFP–NS4B fusion protein located to the ER membrane and to foci that were attached to the ER. These membrane-associated foci (MAFs) could be related to the membrane alterations observed in cells that replicate HCV RNA. The relationship of MAFs to pre-existing cellular structures is not known. Indirect immunofluorescence analysis demonstrated that they did not contain a cellular marker for vesicles, which have been implicated in the replication of other viruses. From photobleaching studies to examine diffusion of NS4B, the GFP-tagged protein had reduced mobility on MAFs compared with on the ER membrane. This slower mobility suggested that NS4B is likely to form different interactions on MAFs and the ER.

scholarly journals Cell Transformation and Proteome Alteration in QSG7701 Cells Transfected with Hepatitis C Virus Non-structural Protein 3

2007 ◽  
Vol 39 (10) ◽  
pp. 751-762 ◽  
Author(s):  
Qiongqiong HE ◽  
Ruixue CHENG ◽  
Zhuchu CHEN ◽  
Xuxian XIAO ◽  
Zhiqiang XIAO ◽  
...  
Keyword(s):  
Hepatitis C Virus ◽  
Hepatitis C ◽  
Cell Transformation ◽  
Structural Protein

Association between variants in the interferon lambda 4 locus and substitutions in the hepatitis C virus non-structural protein 5A

2015 ◽  
Vol 63 (3) ◽  
pp. 554-563 ◽  
Author(s):  
Sakura Akamatsu ◽  
C. Nelson Hayes ◽  
Hidenori Ochi ◽  
Takuro Uchida ◽  
Hiromi Kan ◽  
...  
Keyword(s):  
Hepatitis C Virus ◽  
Hepatitis C ◽  
Structural Protein ◽  
Interferon Lambda

Mechanism of Zinc Ejection by Disulfiram in Nonstructural Protein 5A

2021 ◽  
Author(s):  
Ashfaq Ur Rehman ◽  
Guodong Zheng ◽  
Bozitao Zhong ◽  
Duan Ni ◽  
Jia-Yi Li ◽  
...  
Keyword(s):  
Hepatitis C Virus ◽  
Hepatitis C ◽  
Nonstructural Protein ◽  
Structural Protein ◽  
Positive Strand ◽  
Positive Strand Rna ◽  
Nonstructural Protein 5A

Hepatitis C virus (HCV) is a notorious member of the enveloped, positive-strand RNA flavivirus family. Non-structural protein 5A (NS5A) plays a key role in HCV replication and assembly. NS5A is...

scholarly journals Hepatitis C Virus Subverts Human Choline Kinase-α To Bridge Phosphatidylinositol-4-Kinase IIIα (PI4KIIIα) and NS5A and Upregulates PI4KIIIα Activation, Thereby Promoting the Translocation of the Ternary Complex to the Endoplasmic Reticulum for Viral Replication

2017 ◽  
Vol 91 (16) ◽  
Author(s):  
Mun-Teng Wong ◽  
Steve S. Chen
Keyword(s):  
Endoplasmic Reticulum ◽  
Hepatitis C Virus ◽  
Hepatitis C ◽  
Viral Replication ◽  
Ternary Complex ◽  
Choline Kinase ◽  
Replication Complex ◽  
Viral Replication Complex ◽  
Phosphatidylinositol 4

ABSTRACT In this study, we elucidated the mechanism by which human choline kinase-α (hCKα) interacts with nonstructural protein 5A (NS5A) and phosphatidylinositol-4-kinase IIIα (PI4KIIIα), the lipid kinase crucial for maintaining the integrity of virus-induced membranous webs, and modulates hepatitis C virus (HCV) replication. hCKα activity positively modulated phosphatidylinositol-4-phosphate (PI4P) levels in HCV-expressing cells, and hCKα-mediated PI4P accumulation was abolished by AL-9, a PI4KIIIα-specific inhibitor. hCKα colocalized with NS5A and PI4KIIIα or PI4P; NS5A expression increased hCKα and PI4KIIIα colocalization; and hCKα formed a ternary complex with PI4KIIIα and NS5A, supporting the functional interplay of hCKα with PI4KIIIα and NS5A. PI4KIIIα inactivation by AL-9 or hCKα inactivation by CK37, a specific hCKα inhibitor, impaired the endoplasmic reticulum (ER) localization and colocalization of these three molecules. Interestingly, hCKα knockdown or inactivation inhibited PI4KIIIα-NS5A binding. In an in vitro PI4KIIIα activity assay, hCKα activity slightly increased PI4KIIIα basal activity but greatly augmented NS5A-induced PI4KIIIα activity, supporting the essential role of ternary complex formation in robust PI4KIIIα activation. Concurring with the upregulation of PI4P production and viral replication, overexpression of active hCKα-R (but not the D288A mutant) restored PI4KIIIα and NS5A translocation to the ER in hCKα stable knockdown cells. Furthermore, active PI4KIIIα overexpression restored PI4P production, PI4KIIIα and NS5A translocation to the ER, and viral replication in CK37-treated cells. Based on our results, hCKα functions as an indispensable regulator that bridges PI4KIIIα and NS5A and potentiates NS5A-stimulated PI4KIIIα activity, which then facilitates the targeting of the ternary complex to the ER for viral replication. IMPORTANCE The mechanisms by which hCKα activity modulates the transport of the hCKα-NS5A complex to the ER are not understood. In the present study, we investigated how hCKα interacts with PI4KIIIα (a key element that maintains the integrity of the “membranous web” structure) and NS5A to regulate viral replication. We demonstrated that HCV hijacks hCKα to bridge PI4KIIIα and NS5A, forming a ternary complex, which then stimulates PI4KIIIα activity to produce PI4P. Pronounced PI4P synthesis then redirects the translocation of the ternary complex to the ER-derived, PI4P-enriched membrane for assembly of the viral replication complex and viral replication. Our study provides novel insights into the indispensable modulatory role of hCKα in the recruitment of PI4KIIIα to NS5A and in NS5A-stimulated PI4P production and reveals a new perspective for understanding the impact of profound PI4KIIIα activation on the targeting of PI4KIIIα and NS5A to the PI4P-enriched membrane for viral replication complex formation.

scholarly journals A Retention Signal Necessary and Sufficient for Endoplasmic Reticulum Localization Maps to the Transmembrane Domain of Hepatitis C Virus Glycoprotein E2

1998 ◽  
Vol 72 (3) ◽  
pp. 2183-2191 ◽  
Author(s):  
Laurence Cocquerel ◽  
Jean-Christophe Meunier ◽  
André Pillez ◽  
Czeslaw Wychowski ◽  
Jean Dubuisson
Keyword(s):  
Endoplasmic Reticulum ◽  
Hepatitis C Virus ◽  
Hepatitis C ◽  
Transmembrane Domain ◽  
Intracellular Localization ◽  
Native Form ◽  
Glycosyl Phosphatidylinositol ◽  
Er Retention ◽  
Er Targeting ◽  
Necessary And Sufficient

ABSTRACT The hepatitis C virus (HCV) genome encodes two envelope glycoproteins (E1 and E2). These glycoproteins interact to form a noncovalent heterodimeric complex which is retained in the endoplasmic reticulum (ER). To identify whether E1 and/or E2 contains an ER-targeting signal potentially involved in ER retention of the E1-E2 complex, these proteins were expressed alone and their intracellular localization was studied. Due to misfolding of E1 in the absence of E2, no conclusion on the localization of its native form could be drawn from the expression of E1 alone. E2 expressed in the absence of E1 was shown to be retained in the ER similarly to E1-E2 complex. Chimeric proteins in which E2 domains were exchanged with corresponding domains of a protein normally transported to the plasma membrane (CD4) were constructed to identify the sequence responsible for its ER retention. The transmembrane domain (TMD) of E2 (C-terminal 29 amino acids) was shown to be sufficient for retention of the ectodomain of CD4 in the ER compartment. Replacement of the E2 TMD by the anchor signal of CD4 or a glycosyl phosphatidylinositol (GPI) moiety led to its expression on the cell surface. In addition, replacement of the E2 TMD by the anchor signal of CD4 or a GPI moiety abolished the formation of E1-E2 complexes. Together, these results suggest that, besides having a role as a membrane anchor, the TMD of E2 is involved in both complex formation and intracellular localization.

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