Assembly of a Functional HCV Glycoprotein Heterodimer

Muriel Lavie,Anny Dewilde ,Jean Dubuisson

doi:10.21775/cimb.009.071

Abstract

The two HCV envelope glycoproteins E1 and E2 are released from HCV polyprotein by signal peptidase cleavages. These glycoproteins are type I transmembrane proteins with a highly glycosylated N-terminal ectodomain and a C-terminal hydrophobic anchor. After their synthesis, HCV glycoproteins E1 and E2 associate as a noncovalent heterodimer. The transmembrane domains of HCV envelope glycoproteins play a major role in E1E2 heterodimer assembly and subcellular localization. The envelope glycoprotein complex E1E2 has been proposed to be essential for HCV entry. However, for a long time, HCV entry studies have remained limited because of the lack of a robust cell culture system to amplify this virus. A few years ago, a model mimicking the entry process of HCV lifecycle has been developed by pseudotyping retroviral particles with native HCV envelope glycoproteins. This model allowed the characterization of functional E1E2 envelope glycoproteins. The data obtained can now be confirmed with the help of a newly developed cell-culture system that allows efficient amplification of HCV (HCVcc). Here, we present the recent data that have been accumulated on the assembly of the functional HCV glycoprotein heterodimer.

Highlights

As obligate intracellular parasites, all viruses must have ways of entering target cells to initiate replication and infection
Conclusion and future directions Studies of the biogenesis of HCV envelope glycoproteins have shown the pivotal role of the transmembrane domains in the assembly of a noncovalent E1E2 heterodimer in the endoplasmic reticulum (ER)
The HCV pseudoparticles (HCVpp) model has allowed the investigation of the role of E1E2 heterodimer in virus entry, the identification of functional regions in HCV envelope glycoproteins and the validation of potential receptors

Summary

Introduction

All viruses must have ways of entering target cells to initiate replication and infection. Site-directed mutagenesis studies have shown that the absence of some glycans in E1 (N1 and N4) and E2 (N8 and N10) leads to misfolding of HCV envelope glycoproteins (Fig. 2) (Goffard et al, 2005; Meunier et al, 1999).

Results

Conclusion