scholarly journals Characterization of Hepatitis C Virus Core Protein Multimerization and Membrane Envelopment: Revelation of a Cascade of Core-Membrane Interactions

2009 ◽  
Vol 83 (19) ◽  
pp. 9923-9939 ◽  
Author(s):  
Li-Shuang Ai ◽  
Yu-Wen Lee ◽  
Steve S.-L. Chen
Keyword(s):  
Hepatitis C Virus ◽  
Hepatitis C ◽  
Complex Formation ◽  
Signal Peptide ◽  
Core Protein ◽  
The Core ◽  
Hcv Core Protein ◽  
Core Proteins ◽  
Multimeric Complex ◽  
Protein Multimerization

ABSTRACT The molecular basis underlying hepatitis C virus (HCV) core protein maturation and morphogenesis remains elusive. We characterized the concerted events associated with core protein multimerization and interaction with membranes. Analyses of core proteins expressed from a subgenomic system showed that the signal sequence located between the core and envelope glycoprotein E1 is critical for core association with endoplasmic reticula (ER)/late endosomes and the core's envelopment by membranes, which was judged by the core's acquisition of resistance to proteinase K digestion. Despite exerting an inhibitory effect on the core's association with membranes, (Z-LL)2-ketone, a specific inhibitor of signal peptide peptidase (SPP), did not affect core multimeric complex formation, suggesting that oligomeric core complex formation proceeds prior to or upon core attachment to membranes. Protease-resistant core complexes that contained both innate and processed proteins were detected in the presence of (Z-LL)2-ketone, implying that core envelopment occurs after intramembrane cleavage. Mutations of the core that prevent signal peptide cleavage or coexpression with an SPP loss-of-function D219A mutant decreased the core's envelopment, demonstrating that SPP-mediated cleavage is required for core envelopment. Analyses of core mutants with a deletion in domain I revealed that this domain contains sequences crucial for core envelopment. The core proteins expressed by infectious JFH1 and Jc1 RNAs in Huh7 cells also assembled into a multimeric complex, associated with ER/late-endosomal membranes, and were enveloped by membranes. Treatment with (Z-LL)2-ketone or coexpression with D219A mutant SPP interfered with both core envelopment and infectious HCV production, indicating a critical role of core envelopment in HCV morphogenesis. The results provide mechanistic insights into the sequential and coordinated processes during the association of the HCV core protein with membranes in the early phase of virus maturation and morphogenesis.

scholarly journals Intramembrane Processing by Signal Peptide Peptidase Regulates the Membrane Localization of Hepatitis C Virus Core Protein and Viral Propagation

2008 ◽  
Vol 82 (17) ◽  
pp. 8349-8361 ◽  
Author(s):  
Kiyoko Okamoto ◽  
Yoshio Mori ◽  
Yasumasa Komoda ◽  
Toru Okamoto ◽  
Masayasu Okochi ◽  
...  
Keyword(s):  
Hepatitis C Virus ◽  
Hepatitis C ◽  
Signal Peptide ◽  
Core Protein ◽  
Biological Significance ◽  
Signal Peptidase ◽  
Signal Peptide Peptidase ◽  
Viral Propagation ◽  
The Core ◽  
Hcv Core Protein

ABSTRACT Hepatitis C virus (HCV) core protein has shown to be localized in the detergent-resistant membrane (DRM), which is distinct from the classical raft fraction including caveolin, although the biological significance of the DRM localization of the core protein has not been determined. The HCV core protein is cleaved off from a precursor polyprotein at the lumen side of Ala191 by signal peptidase and is then further processed by signal peptide peptidase (SPP) within the transmembrane region. In this study, we examined the role of SPP in the localization of the HCV core protein in the DRM and in viral propagation. The C terminus of the HCV core protein cleaved by SPP in 293T cells was identified as Phe177 by mass spectrometry. Mutations introduced into two residues (Ile176 and Phe177) upstream of the cleavage site of the core protein abrogated processing by SPP and localization in the DRM fraction. Expression of a dominant-negative SPP or treatment with an SPP inhibitor, L685,458, resulted in reductions in the levels of processed core protein localized in the DRM fraction. The production of HCV RNA in cells persistently infected with strain JFH-1 was impaired by treatment with the SPP inhibitor. Furthermore, mutant JFH-1 viruses bearing SPP-resistant mutations in the core protein failed to propagate in a permissive cell line. These results suggest that intramembrane processing of HCV core protein by SPP is required for the localization of the HCV core protein in the DRM and for viral propagation.

scholarly journals Proteasome Activator PA28γ-Dependent Nuclear Retention and Degradation of Hepatitis C Virus Core Protein

2003 ◽  
Vol 77 (19) ◽  
pp. 10237-10249 ◽  
Author(s):  
Kohji Moriishi ◽  
Tamaki Okabayashi ◽  
Kousuke Nakai ◽  
Kyoji Moriya ◽  
Kazuhiko Koike ◽  
...  
Keyword(s):  
Hepatitis C Virus ◽  
Hepatitis C ◽  
Core Protein ◽  
Regulatory Protein ◽  
Hcv Infection ◽  
Nuclear Retention ◽  
Proteasome Activator ◽  
Hcv Core Protein ◽  
Core Proteins ◽  
Chronic Hcv

ABSTRACT Hepatitis C virus (HCV) core protein plays an important role in the formation of the viral nucleocapsid and a regulatory protein involved in hepatocarcinogenesis. In this study, we have identified proteasome activator PA28γ (11S regulator γ) as an HCV core binding protein by using yeast two-hybrid system. This interaction was demonstrated not only in cell culture but also in the livers of HCV core transgenic mice. These findings are extended to human HCV infection by the observation of this interaction in liver specimens from a patient with chronic HCV infection. Neither the interaction of HCV core protein with other PA28 subtypes nor that of PA28γ with other Flavivirus core proteins was detected. Deletion of the PA28γ-binding region from the HCV core protein or knockout of the PA28γ gene led to the export of the HCV core protein from the nucleus to the cytoplasm. Overexpression of PA28γ enhanced the proteolysis of the HCV core protein. Thus, the nuclear retention and stability of the HCV core protein is regulated via a PA28γ-dependent pathway through which HCV pathogenesis may be exerted.

scholarly journals Interaction of Hepatitis C Virus Core Protein with Viral Sense RNA and Suppression of Its Translation

1999 ◽  
Vol 73 (12) ◽  
pp. 9718-9725 ◽  
Author(s):  
Takashi Shimoike ◽  
Shigetaka Mimori ◽  
Hideki Tani ◽  
Yoshiharu Matsuura ◽  
Tatsuo Miyamura
Keyword(s):  
Hepatitis C Virus ◽  
Hepatitis C ◽  
Core Protein ◽  
Firefly Luciferase ◽  
Encephalomyocarditis Virus ◽  
Hcv Rna ◽  
Dependent Manner ◽  
Genomic Rna ◽  
The Core ◽  
Hcv Core Protein

ABSTRACT To clarify the binding properties of hepatitis C virus (HCV) core protein and its viral RNA for the encapsidation, morphogenesis, and replication of HCV, the specific interaction of HCV core protein with its genomic RNA synthesized in vitro was examined in an in vivo system. The positive-sense RNA from the 5′ end to nucleotide (nt) 2327, which covers the 5′ untranslated region (5′UTR) and a part of the coding region of HCV structural proteins, interacted with HCV core protein, while no interaction was observed in the same region of negative-sense RNA and in other regions of viral and antiviral sense RNAs. The internal ribosome entry site (IRES) exists around the 5′UTR of HCV; therefore, the interaction of the core protein with this region of HCV RNA suggests that there is some effect on its cap-independent translation. Cells expressing HCV core protein were transfected with reporter RNAs consisting of nt 1 to 709 of HCV RNA (the 5′UTR of HCV and about two-thirds of the core protein coding regions) followed by a firefly luciferase gene (HCV07Luc RNA). The translation of HCV07Luc RNA was suppressed in cells expressing the core protein, whereas no significant suppression was observed in the case of a reporter RNA possessing the IRES of encephalomyocarditis virus followed by a firefly luciferase. This suppression by the core protein occurred in a dose-dependent manner. The expression of the E1 envelope protein of HCV or β-galactosidase did not suppress the translation of both HCV and EMCV reporter RNAs. We then examined the regions that are important for suppression of translation by the core protein and found that the region from nt 1 to 344 was enough to exert this suppression. These results suggest that the HCV core protein interacts with viral genomic RNA at a specific region to form nucleocapsids and regulates the expression of HCV by interacting with the 5′UTR.

scholarly journals Hepatitis C Virus Core Protein Is a Dimeric Alpha-Helical Protein Exhibiting Membrane Protein Features

2005 ◽  
Vol 79 (17) ◽  
pp. 11353-11365 ◽  
Author(s):  
Steeve Boulant ◽  
Christophe Vanbelle ◽  
Christine Ebel ◽  
François Penin ◽  
Jean-Pierre Lavergne
Keyword(s):  
Hepatitis C Virus ◽  
Hepatitis C ◽  
Rna Binding ◽  
Core Protein ◽  
Limited Proteolysis ◽  
Hydrophobic Domain ◽  
Fluorescence Measurements ◽  
Hcv Core Protein ◽  
Core Proteins

ABSTRACT The building block of hepatitis C virus (HCV) nucleocapsid, the core protein, together with viral RNA, is composed of different domains involved in RNA binding and homo-oligomerization. The HCV core protein 1-169 (CHCV169) and its N-terminal region from positions 1 to 117 (CHCV117) were expressed in Escherichia coli and purified to homogeneity suitable for biochemical and biophysical characterizations. The overall conformation and the oligomeric properties of the resulting proteins CHCV169 and CHCV117 were investigated by using analytical centrifugation, circular dichroism, intrinsic fluorescence measurements, and limited proteolysis. Altogether, our results show that core protein (CHCV169) behaves as a membranous protein and forms heterogeneous soluble micelle-like aggregates of high molecular weight in the absence of detergent. In contrast, it behaves, in the presence of mild detergent, as a soluble, well-folded, noncovalent dimer. Similar to findings observed for core proteins of HCV-related flaviviruses, the HCV core protein is essentially composed of α-helices (50%). In contrast, CHCV117 is soluble and monodispersed in the absence of detergent but is unfolded. It appears that the folding of the highly basic domain from positions 2 to 117 (2-117 domain) depends on the presence of the 117-169 hydrophobic domain, which contains the structural determinants ensuring the binding of core with cellular membranes. Finally, our findings provide valuable information for further investigations on isolated core protein, as well as for attempts to reconstitute nucleocapsid particles in vitro.

scholarly journals Efficient cleavage by signal peptide peptidase requires residues within the signal peptide between the core and E1 proteins of hepatitis C virus strain J1

2006 ◽  
Vol 87 (3) ◽  
pp. 623-627 ◽  
Author(s):  
R. Graham Hope ◽  
Marion J. McElwee ◽  
John McLauchlan
Keyword(s):  
Hepatitis C Virus ◽  
Hepatitis C ◽  
Signal Peptide ◽  
Core Protein ◽  
Signal Peptidase ◽  
Wild Type ◽  
Signal Peptide Peptidase ◽  
Standard Buffer ◽  
Hcv Core Protein ◽  
Mutant Forms

Maturation of hepatitis C virus (HCV) core protein requires cleavage by signal peptidase (SP) and signal peptide peptidase (SPP) at a signal peptide between core and the E1 glycoprotein. For HCV strain Glasgow, amino acids Ala180, Ser183 and Cys184 within the signal peptide have previously been shown to be essential for efficient SPP cleavage. By contrast, these residues apparently did not contribute to core maturation in HCV strain J1. In the present study, the source of this discrepancy has been analysed and it is concluded that interpretation of the strain J1 data was incorrect, due to the inability to separate wild-type and mutant forms of core on gels by using standard buffer systems.

scholarly journals Hepatitis C Virus Genotype 1b Core Protein Does Not Exert Immunomodulatory Effects on Virus-Induced Cellular Immunity

2002 ◽  
Vol 76 (3) ◽  
pp. 990-997 ◽  
Author(s):  
Zhang-Xu Liu ◽  
Hiroshi Nishida ◽  
Jian-Wen He ◽  
Michael M. C. Lai ◽  
Ni Feng ◽  
...  
Keyword(s):  
Hepatitis C Virus ◽  
Hepatitis C ◽  
Liver Injury ◽  
Core Protein ◽  
Virus Genotype ◽  
Hcv Genotype ◽  
Cell Functions ◽  
The Core ◽  
Genotype 1B ◽  
Hcv Core Protein

ABSTRACT The hepatitis C virus (HCV) core protein is among the most conserved proteins in HCV and is known to induce sensitization of cytotoxic T lymphocytes (CTL). Therefore, it is a prime candidate for a component of a potential HCV vaccine. The HCV core protein has, however, been reported to exert multiple effects on cell functions, raising questions as to its suitability for this purpose. This question was investigated here with mice into which replication-deficient adenoviruses expressing core protein of an HCV genotype 1b isolate were injected. We show that induction of cytokines in response to the infection, infiltration of lymphocytes into the infected liver, priming of virus-specific CTL, and liver injury are not modulated by expression of the core protein in the liver. Moreover, no changes in the sensitivity to tumor necrosis factor alpha- or Fas-mediated liver injury are demonstrable. A similar lack of demonstrable effects of the core protein on immune functions has also been obtained using transgenic mice expressing another HCV genotype 1b core protein. It is concluded that the HCV core protein of genotype 1b has no modulatory effects on induction of virus-specific immune responses and may therefore be a suitable component of an HCV vaccine.

scholarly journals Ectopic Expression of Hepatitis C Virus Core Protein Differentially Regulates Nuclear Transcription Factors

1998 ◽  
Vol 72 (12) ◽  
pp. 9722-9728 ◽  
Author(s):  
Anju Shrivastava ◽  
Sunil K. Manna ◽  
Ranjit Ray ◽  
Bharat B. Aggarwal
Keyword(s):  
Transcription Factors ◽  
Hepatitis C Virus ◽  
Hepatitis C ◽  
Inflammatory Responses ◽  
Core Protein ◽  
Ectopic Expression ◽  
Cellular Growth ◽  
Mitogen Activated Protein Kinase ◽  
The Core ◽  
Hcv Core Protein

ABSTRACT The putative core protein of hepatitis C virus (HCV) regulates cellular growth and a number of cellular promoters. To further understand its effect, we investigated the role of the core protein in the endogenous regulation of two distinct transcription factors, nuclear factor-κB (NF-κB) and activating protein-1 (AP-1), and the related mitogen-activated protein kinase kinase (MAPKK) and c-Jun N-terminal kinase (JNK). Stable cell transfectants expressing the HCV core protein suppressed tumor necrosis factor (TNF)-induced NF-κB activation. Supershift analysis revealed that NF-κB consists of p50 and p65 subunits. This correlated with inhibition of the degradation of IκBα, the inhibitory subunit of NF-κB. The effect was not specific to TNF, as suppression in core protein-expressing cells was also observed in response to a number of other inflammatory agents known to activate NF-κB. In contrast to the effect on NF-κB, the HCV core protein constitutively activated AP-1, which correlated with the activation of JNK and MAPKK, which are known to regulate AP-1. These observations indicated that the core protein targets transcription factors known to be involved in the regulation of inflammatory responses and the immune system.

scholarly journals Self-Assembly of Nucleocapsid-Like Particles from Recombinant Hepatitis C Virus Core Protein

2001 ◽  
Vol 75 (5) ◽  
pp. 2119-2129 ◽  
Author(s):  
Meghan Kunkel ◽  
Marta Lorinczi ◽  
René Rijnbrand ◽  
Stanley M. Lemon ◽  
Stanley J. Watowich
Keyword(s):  
Hepatitis C Virus ◽  
Hepatitis C ◽  
Self Assembly ◽  
High Throughput Screening ◽  
Core Protein ◽  
Rna Molecules ◽  
The Core ◽  
Assembly Pathway ◽  
Core Proteins

ABSTRACT Little is known about the assembly pathway and structure of hepatitis C virus (HCV) since insufficient quantities of purified virus are available for detailed biophysical and structural studies. Here, we show that bacterially expressed HCV core proteins can efficiently self-assemble in vitro into nucleocapsid-like particles. These particles have a regular, spherical morphology with a modal distribution of diameters of approximately 60 nm. Self-assembly of nucleocapsid-like particles requires structured RNA molecules. The 124 N-terminal residues of the core protein are sufficient for self-assembly into nucleocapsid-like particles. Inclusion of the carboxy-terminal domain of the core protein modifies the core assembly pathway such that the resultant particles have an irregular outline. However, these particles are similar in size and shape to those assembled from the 124 N-terminal residues of the core protein. These results provide novel opportunities to delineate protein-protein and protein-RNA interactions critical for HCV assembly, to study the molecular details of HCV assembly, and for performing high-throughput screening of assembly inhibitors.

scholarly journals Functional properties of a 16 kDa protein translated from an alternative open reading frame of the core-encoding genomic region of hepatitis C virus

2004 ◽  
Vol 85 (8) ◽  
pp. 2299-2306 ◽  
Author(s):  
Arnab Basu ◽  
Robert Steele ◽  
Ranjit Ray ◽  
Ratna B. Ray
Keyword(s):  
Hepatitis C Virus ◽  
Hepatitis C ◽  
Core Protein ◽  
Genomic Region ◽  
Open Reading Frame ◽  
Transcriptional Level ◽  
Reading Frame ◽  
F Protein ◽  
Hcv Core Protein ◽  
Core Proteins

Hepatitis C virus (HCV) often causes persistent infection in humans. This could be due in part to the effect of viral proteins on cellular gene expression. Earlier observations suggest that the HCV core protein expressed from genotype 1a modulates important cellular genes at the transcriptional level, affects programmed cell death (apoptosis) and promotes cell growth. Recently, different groups of investigators have reported the translation of an ∼16 kDa protein (named F/ARFP/core+1 ORF) from an alternate open reading frame of the HCV core-encoding genomic region. The functional significance of this F protein is presently unknown. Thus, whether the F and core proteins have both shared and distinct functions was investigated here. The experimental observations suggested that the F protein does not significantly modulate c-myc, hTERT and p53 promoter activities, unlike the HCV core protein. Interestingly, the F protein repressed p21 expression. Further studies indicated that the F protein does not inhibit tumour necrosis factor alpha-mediated apoptosis of HepG2 cells or promote rat embryo fibroblast growth. Taken together, these results suggest that the F protein does not share major properties identified previously for the HCV core protein, other than regulating p21 expression.

scholarly journals Core protein cleavage by signal peptide peptidase is required for hepatitis C virus-like particle assembly

2006 ◽  
Vol 87 (4) ◽  
pp. 855-860 ◽  
Author(s):  
Malika Ait-Goughoulte ◽  
Christophe Hourioux ◽  
Romuald Patient ◽  
Sylvie Trassard ◽  
Denys Brand ◽  
...  
Keyword(s):  
Hepatitis C Virus ◽  
Hepatitis C ◽  
Signal Peptide ◽  
Semliki Forest Virus ◽  
Core Protein ◽  
Protein Cleavage ◽  
Particle Assembly ◽  
Signal Peptide Peptidase ◽  
Hcv Core Protein ◽  
Er Membrane

Hepatitis C virus (HCV) core protein, expressed with a Semliki Forest virus replicon, self-assembles into HCV-like particles (HCV-LP) at the endoplasmic reticulum (ER) membrane, providing an opportunity to study HCV assembly and morphogenesis by electron microscopy. This model was used to investigate whether the processing of the HCV core protein by the signal peptide peptidase (SPP) is required for the HCV-LP assembly. Several mutants were designed as there are conflicting reports concerning the cleavage of mutant proteins by SPP. Production of the only core mutant protein that escaped SPP processing led to the formation of multiple layers of electron-dense ER membrane, with no evidence of HCV-LP assembly. These data shed light on the HCV core residues involved in SPP cleavage and suggest that this cleavage is essential for HCV assembly.

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