丙肝病毒 (HCV) 是肝病和肝癌的一個主要病因,。由于沒有保護性疫苗,，也由于治療方案仍然有限，尋找新的治療目標便顯得很重要,。James Chou及其同事在這篇論文中報告了低聚丙肝病毒“viroporin p7”的結構,，是通過NMR譜獲得的。該蛋白能自組成一個可傳導陽離子的通道復合物,。該通道六聚物的一個高分辨率視圖顯示了新穎的漏斗狀通道結構,，而功能研究則識別出了對通道活性重要的殘體。（生物谷Bioon.com）
生物谷推薦英文摘要：
Nature doi:10.1038/nature12283
Unusual architecture of the p7 channel from hepatitis C virus
Bo OuYang,Shiqi Xie,Marcelo J. Berardi,Xinhao Zhao, Jyoti Dev, Wenjing Yu,Bing Sun & James J. Chou
The hepatitis C virus (HCV) has developed a small membrane protein, p7, which remarkably can self-assemble into a large channel complex that selectively conducts cations. We wanted to examine the structural solution that the viroporin adopts in order to achieve selective cation conduction, because p7 has no homology with any of the known prokaryotic or eukaryotic channel proteins. The activity of p7 can be inhibited by amantadine and rimantadine, which are potent blockers of the influenza M2 channel and licensed drugs against influenza infections. The adamantane derivatives have been used in HCV clinical trials, but large variation in drug efficacy among the various HCV genotypes has been difficult to explain without detailed molecular structures. Here we determine the structures of this HCV viroporin as well as its drug-binding site using the latest nuclear magnetic resonance (NMR) technologies. The structure exhibits an unusual mode of hexameric assembly, where the individual p7 monomers, i, not only interact with their immediate neighbours, but also reach farther to associate with the i+2 and i+3 monomers, forming a sophisticated, funnel-like architecture. The structure also points to a mechanism of cation selection: an asparagine/histidine ring that constricts the narrow end of the funnel serves as a broad cation selectivity filter, whereas an arginine/lysine ring that defines the wide end of the funnel may selectively allow cation diffusion into the channel. Our functional investigation using whole-cell channel recording shows that these residues are critical for channel activity. NMR measurements of the channel–drug complex revealed six equivalent hydrophobic pockets between the peripheral and pore-forming helices to which amantadine or rimantadine binds, and compound binding specifically to this position may allosterically inhibit cation conduction by preventing the channel from opening. Our data provide a molecular explanation for p7-mediated cation conductance and its inhibition by adamantane derivatives.
