Publication Date:
2013-06-07
Description:
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.〈br /〉〈br /〉〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3725310/" target="_blank"〉〈img src="https://static.pubmed.gov/portal/portal3rc.fcgi/4089621/img/3977009" border="0"〉〈/a〉 〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3725310/" target="_blank"〉This paper as free author manuscript - peer-reviewed and accepted for publication〈/a〉〈br /〉〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉OuYang, Bo -- Xie, Shiqi -- Berardi, Marcelo J -- Zhao, Xinhao -- Dev, Jyoti -- Yu, Wenjing -- Sun, Bing -- Chou, James J -- GM094608/GM/NIGMS NIH HHS/ -- U54 GM094608/GM/NIGMS NIH HHS/ -- England -- Nature. 2013 Jun 27;498(7455):521-5. doi: 10.1038/nature12283. Epub 2013 Jun 5.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, Massachusetts 02115, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/23739335" target="_blank"〉PubMed〈/a〉
Keywords:
Adamantane/analogs & derivatives/chemistry/metabolism/pharmacology
;
Binding Sites
;
Diffusion
;
Hepacivirus/*chemistry
;
Microscopy, Electron
;
Models, Biological
;
Models, Molecular
;
Nuclear Magnetic Resonance, Biomolecular
;
Porosity
;
Rimantadine/chemistry/metabolism/pharmacology
;
Structure-Activity Relationship
;
Viral Proteins/antagonists & inhibitors/*chemistry/metabolism/ultrastructure
Print ISSN:
0028-0836
Electronic ISSN:
1476-4687
Topics:
Biology
,
Chemistry and Pharmacology
,
Medicine
,
Natural Sciences in General
,
Physics
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