Identification of New Functional Regions in Hepatitis C Virus Envelope Glycoprotein E2

Albecka, Anna; Montserret, Roland; Krey, Thomas; Tarr, Alexander W.; Diesis, Eric; Ball, Jonathan K.; Descamps, Véronique; Duverlie, Gilles; Rey, F.A.; Pénin, François; Dubuisson, Jean

doi:10.1128/jvi.02170-10

Cited by 64 publications

(73 citation statements)

References 75 publications

(78 reference statements)

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“…from the same HCV strain) as they have co-evolved within a given HCV genotype to achieve interrelations for optimizing cell entry functions. Interestingly, our work is complementary to a recent study (41) that used a similar strategy to identify that E1 JFH1 (gt2a) does not form functional heterodimers when associated with E2 from H77 (gt1a). This study demonstrated intradomain interactions within E2 but did not focus on E1.…”

Section: Discussionsupporting

confidence: 53%

Identification of Interactions in the E1E2 Heterodimer of Hepatitis C Virus Important for Cell Entry

Maurin

Fresquet

Granio

et al. 2011

Journal of Biological Chemistry

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Several conserved domains critical for E1E2 assembly and hepatitis C virus entry have been identified in E1 and E2 envelope glycoproteins. However, the role of less conserved domains involved in cross-talk between either glycoprotein must be defined to fully understand how E1E2 undergoes conformational changes during cell entry. To characterize such domains and to identify their functional partners, we analyzed a set of intergenotypic E1E2 heterodimers derived from E1 and E2 of different genotypes. The infectivity of virions indicated that Con1 E1 did not form functional heterodimers when associated with E2 from H77. Biochemical analyses demonstrated that the reduced infectivity was not related to alteration of conformation and incorporation of Con1 E1/H77 E2 heterodimers but rather to cell entry defects. Thus, we generated chimeric E1E2 glycoproteins by exchanging different domains of each protein in order to restore functional heterodimers. We found that both the ectodomain and transmembrane domain of E1 influenced infectivity. Site-directed mutagenesis highlighted the role of amino acids 359, 373, and 375 in transmembrane domain in entry. In addition, we identified one domain involved in entry within the N-terminal part of E1, and we isolated a motif at position 219 that is critical for H77 function. Interestingly, using additional chimeric E1E2 complexes harboring substitutions in this motif, we found that the transmembrane domain of E1 acts as a partner of this motif. Therefore, we characterized domains of E1 and E2 that have co-evolved inside a given genotype to optimize their interactions and allow efficient entry. Hepatitis C virus (HCV)4 is an important public health concern worldwide, as it is a major cause of chronic hepatitis, cirrhosis, and hepatocellular carcinoma. HCV is an enveloped virus that belongs to the Hepacivirus genus of the Flaviviridae family (1). The two surface glycoproteins, E1 and E2, are processed by signal peptidases of the endoplasmic reticulum from a 3000-amino acid-long polyprotein encoded by the HCV genome (2).Because of difficulties in propagating HCV in cell culture, many gaps remain in our understanding of the functions of E1 and E2. A major advance in the investigation of their functions was the development of HCV pseudoparticles (HCVpp) consisting of native HCV envelope glycoproteins E1 and E2 assembled onto retroviral core particles (3-5). Extensive characterization of HCVpp showed that they mimic the early steps of the HCV life cycle (6, 7). Furthermore, data obtained with HCVpp can now also be confirmed with the developed cell culture system that allows efficient amplification of HCV (HCVcc) (8 -10).The E1 (31 kDa) and E2 (70 kDa) proteins are glycosylated in their large N-terminal ectodomains and are anchored into the membrane by their C-terminal transmembrane domains. E1 and E2 form a heterodimer stabilized by noncovalent interactions that is retained in the endoplasmic reticulum (11). This oligomer was thought for a long time to be the prebudding form of the functio...

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Section: Discussionsupporting

confidence: 53%

Identification of Interactions in the E1E2 Heterodimer of Hepatitis C Virus Important for Cell Entry

Maurin

Fresquet

Granio

et al. 2011

Journal of Biological Chemistry

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“…Finally, DIII is connected to the transmembrane domain by the flexible stem region. This latter region is potentially involved in envelope protein heterodimerization as well as in virus entry [10,12]. An amphipathic helix, which likely folds upon membrane binding has been identified in the C-terminal part of the stem region and it has been proposed that this region might be involved in the reorganization of glycoprotein complexes taking place during the fusion process [10].…”

Section: Viral Particlementioning

confidence: 99%

“…The DI domain consists of eight b-strands and is extended on the N-terminus by hypervariable region 1 (HVR1). This domain, which contains determinants for CD81 interaction, has recently been functionally confirmed [10]. The DII domain includes hypervariable region 2 (HVR2) and its most conserved part is suggested to act as a fusion loop (a.a. 502-520) that inserts into the target membrane during the first step of membrane fusion.…”

Section: Viral Particlementioning

confidence: 99%

“…The secondary and tertiary structures of envelope glycoproteins are proposed to be similar among the members of the Flaviviridae family, suggesting that HCV envelope glycoproteins belong to class II fusion proteins [9,10]. Recently, the identification of 9 intramolecular disulfide bonds in soluble E2 has shed light on its structure [11].…”

Section: Viral Particlementioning

confidence: 99%

“…Surprisingly, other non-conserved regions like HVR2 and IgVR are essential for the assembly of functional E1E2 heterodimers [10,16,17].…”

Section: Viral Particlementioning

confidence: 99%

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Hepatitis C virus entry into the hepatocyte

Belouzard¹,

Cocquerel²,

Dubuisson³

2011

Open Life Sciences

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Hepatitis C virus (HCV) is a small enveloped virus with a positive stranded RNA genome belonging to the Flaviviridae family. The virion has the unique ability of forming a complex with lipoproteins, which is known as the lipoviroparticle. Lipoprotein components as well as the envelope proteins, E1 and E2, play a key role in virus entry into the hepatocyte. HCV entry is a complex multistep process involving sequential interactions with several cell surface proteins. The virus relies on glycosaminoglycans and possibly the low-density lipoprotein receptors to attach to cells. Furthermore, four specific entry factors are involved in the following steps which lead to virus internalization and fusion in early endosomes. These molecules are the scavenger receptor SRB1, tetraspanin CD81 and two tight junction proteins, Claudin-1 and Occludin. Although they are essential to HCV entry, the precise role of these molecules is not completely understood. Finally, hepatocytes are highly polarized cells and which likely affects the entry process. Our current knowledge on HCV entry is summarized in this review.

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Structure and Molecular Virology

McGarvey

Houghton

2013

Viral Hepatitis

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Identification of New Functional Regions in Hepatitis C Virus Envelope Glycoprotein E2

Cited by 64 publications

References 75 publications

Identification of Interactions in the E1E2 Heterodimer of Hepatitis C Virus Important for Cell Entry

Identification of Interactions in the E1E2 Heterodimer of Hepatitis C Virus Important for Cell Entry

Hepatitis C virus entry into the hepatocyte

Structure and Molecular Virology

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