Structure of the core ectodomain of the hepatitis C virus envelope glycoprotein 2

摘要

Hepatitis C virus (HCY) is a significant public health concern with approximately 160 million people infected worldwide. HCV infection often results in chronic hepatitis, liver cirrhosis and hepatocellular carcinoma. No vaccine is available and current therapies are effective against some, but not all, genotypes. HCV is an enveloped virus with two surface glycoproteins (E1 and E2). E2 binds to the host cell through interactions with scavenger receptor class B type Ⅰ (SR-BI) and CD81, and serves as a target for neutralizing antibodies. Little is known about the molecular mechanism that mediates cell entry and membrane fusion, although E2 is predicted to be a class Ⅱ viral fusion protein. Here we describe the structure of the E2 core domain in complex with an antigen-binding fragment (Fab) at 2.4 A resolution. The E2 core has a compact, globular domain structure, consisting mostly of β-strands and random coil with two small α-helices. The strands are arranged in two, perpendicular sheets (A and B), which are held together by an extensive hydrophobic core and disulph-ide bonds. Sheet A has an IgG-like fold that is commonly found in viral and cellular proteins, whereas sheet B represents a novel fold. Solution-based studies demonstrate that the full-length E2 ectodo-main has a similar globular architecture and does not undergo significant conformational or oligomeric rearrangements on exposure to low pH. Thus, the IgG-like fold is the only feature that E2 shares with class Ⅱ membrane fusion proteins. These results provide unprecedented insights into HCV entry and will assist in developing an HCV vaccine and new inhibitors.%目前还没有针对丙肝病毒的疫苗，所以重要的是要对该病毒的感染过程有更多了解。Joseph Marcotrigiano及同事获得了丙肝病毒表面糖蛋白E2的核心域的晶体结构。该结构显示，与人们的预料相反的是，E2不大可能是病毒融合蛋白。这项研究有助于澄清E2所起作用以及丙肝病毒的进入机制。