Identification of Interactions in the E1E2 Heterodimer of Hepatitis C Virus Important for Cell Entry.
Studies with HCVpp and HCVcc systems have shown that the envelope glycoprotein complex E1E2 is essential for HCV entry. However, due to difficulties in propagating HCV in cell culture and studying 3D structure of the glycoproteins, many gaps remain in our understanding of the precise functions of the two glycoproteins E1 and E2 and their interactions during entry. In order to characterize the cross-talk between E1 and E2 domains during conformational changes necessary for entry process, we assumed that such domains have co-evolved inside a given genotype in order to optimize their interactions and achieve entry function efficiently. In this report, we identified non optimal intergenotypic heterodimers that we used to identify less conserved domains involved in E1E2 interactions. We focused on E1E2 intergenotypic heterodimers between H77 (gt1a) and Con1 (gt1b) strains, and we generated chimeras in E1 by substituting H77 for Con1 sequences and vice versa, in order to restore optimal entry function. We discovered that a N-terminal domain of E1 H77 is essential for the capacity of E1E2 H77 heterodimer to mediate membrane fusion and hence, the entry process. Interestingly, we also found that this N-terminus motif and the transmembrane domain of E1 H77 need to be homologous, i.e., derived from the same strain, in order to achieve optimal entry functions. Furthermore, this interaction is crucial in the entry process of H77/JFH1 HCVcc chimera and seems genotype-dependant suggesting,that the cross-talks within E1 depends on E1 and E2 strain.
Maurin G, Fresquet J, Granio O, Wychowski C, Cosset FL, Lavillette D. J Biol Chem. 2011 Jul 8;286(27):23865-76.