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Unusual architecture of the p7 channel from hepatitis C virus


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 cations1,2,3,4. 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 rimantadine2,5, which are potent blockers of the influenza M2 channel6 and licensed drugs against influenza infections7. The adamantane derivatives have been used in HCV clinical trials8, 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.

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Figure 1: NMR structure of the p7(5a) hexamer and its comparison to the EM map.
Figure 2: The pore properties of the p7(5a) channel.
Figure 3: NMR characterization of the amantadine binding site.
Figure 4: A model for amantadine or rimantadine inhibition of the p7 channel.

Accession codes


Protein Data Bank

Data deposits

The structure is deposited in the Protein Data Bank under the accession number 2M6X.


  1. 1

    Moradpour, D., Penin, F. & Rice, C. M. Replication of hepatitis C virus. Nature Rev. Microbiol. 5, 453–463 (2007)

    CAS  Article  Google Scholar 

  2. 2

    Griffin, S. D. et al. The p7 protein of hepatitis C virus forms an ion channel that is blocked by the antiviral drug, amantadine. FEBS Lett. 535, 34–38 (2003)

    CAS  Article  Google Scholar 

  3. 3

    Pavlovic, D. et al. The hepatitis C virus p7 protein forms an ion channel that is inhibited by long-alkyl-chain iminosugar derivatives. Proc. Natl Acad. Sci. USA 100, 6104–6108 (2003)

    ADS  CAS  Article  Google Scholar 

  4. 4

    Luik, P. et al. The 3-dimensional structure of a hepatitis C virus p7 ion channel by electron microscopy. Proc. Natl Acad. Sci. USA 106, 12712–12716 (2009)

    ADS  CAS  Article  Google Scholar 

  5. 5

    Griffin, S. et al. Genotype-dependent sensitivity of hepatitis C virus to inhibitors of the p7 ion channel. Hepatology 48, 1779–1790 (2008)

    CAS  Article  Google Scholar 

  6. 6

    Wang, C., Takeuchi, K., Pinto, L. H. & Lamb, R. A. Ion channel activity of influenza A virus M2 protein: characterization of the amantadine block. J. Virol. 67, 5585–5594 (1993)

    CAS  PubMed  PubMed Central  Google Scholar 

  7. 7

    Davies, W. L. et al. Antiviral activity of 1-sdamantanamine (amantadine). Science 144, 862–863 (1964)

    ADS  CAS  Article  Google Scholar 

  8. 8

    Mihm, U. et al. Amino acid variations in hepatitis C virus p7 and sensitivity to antiviral combination therapy with amantadine in chronic hepatitis C. Antivir. Ther. 11, 507–519 (2006)

    CAS  PubMed  Google Scholar 

  9. 9

    Fischer, W. B. & Sansom, M. S. Viral ion channels: structure and function. Biochim. Biophys. Acta 1561, 27–45 (2002)

    CAS  Article  Google Scholar 

  10. 10

    Nieva, J. L., Madan, V. & Carrasco, L. Viroporins: structure and biological functions. Nature Rev. Microbiol. 10, 563–574 (2012)

    CAS  Article  Google Scholar 

  11. 11

    Steinmann, E. et al. Antiviral effects of amantadine and iminosugar derivatives against hepatitis C virus. Hepatology 46, 330–338 (2007)

    CAS  Article  Google Scholar 

  12. 12

    Montserret, R. et al. NMR structure and ion channel activity of the p7 protein from hepatitis C virus. J. Biol. Chem. 285, 31446–31461 (2010)

    CAS  Article  Google Scholar 

  13. 13

    Premkumar, A., Wilson, L., Ewart, G. D. & Gage, P. W. Cation-selective ion channels formed by p7 of hepatitis C virus are blocked by hexamethylene amiloride. FEBS Lett. 557, 99–103 (2004)

    CAS  Article  Google Scholar 

  14. 14

    Wozniak, A. L. et al. Intracellular proton conductance of the hepatitis C virus p7 protein and its contribution to infectious virus production. PLoS Pathog. 6, e1001087 (2010)

    Article  Google Scholar 

  15. 15

    Sakai, A. et al. The p7 polypeptide of hepatitis C virus is critical for infectivity and contains functionally important genotype-specific sequences. Proc. Natl Acad. Sci. USA 100, 11646–11651 (2003)

    ADS  CAS  Article  Google Scholar 

  16. 16

    Jones, C. T., Murray, C. L., Eastman, D. K., Tassello, J. & Rice, C. M. Hepatitis C virus p7 and NS2 proteins are essential for production of infectious virus. J. Virol. 81, 8374–8383 (2007)

    CAS  Article  Google Scholar 

  17. 17

    Steinmann, E. et al. Hepatitis C virus p7 protein is crucial for assembly and release of infectious virions. PLoS Pathog. 3, e103 (2007)

    Article  Google Scholar 

  18. 18

    Popescu, C. I. et al. NS2 protein of hepatitis C virus interacts with structural and non-structural proteins towards virus assembly. PLoS Pathog. 7, e1001278 (2011)

    CAS  Article  Google Scholar 

  19. 19

    Vieyres, G. et al. Subcellular localization and function of an epitope-tagged p7 viroporin in hepatitis C virus-producing cells. J. Virol. 87, 1664–1678 (2013)

    CAS  Article  Google Scholar 

  20. 20

    Cook, G. A. & Opella, S. J. Secondary structure, dynamics, and architecture of the p7 membrane protein from hepatitis C virus by NMR spectroscopy. Biochim. Biophys. Acta 1808, 1448–1453 (2011)

    CAS  Article  Google Scholar 

  21. 21

    Stouffer, A. L. et al. Structural basis for the function and inhibition of an influenza virus proton channel. Nature 451, 596–599 (2008)

    ADS  CAS  Article  Google Scholar 

  22. 22

    Cady, S. D. et al. Structure of the amantadine binding site of influenza M2 proton channels in lipid bilayers. Nature 463, 689–692 (2010)

    ADS  CAS  Article  Google Scholar 

  23. 23

    Pielak, R. M., Oxenoid, K. & Chou, J. J. Structural investigation of rimantadine inhibition of the AM2–BM2 chimera channel of influenza viruses. Structure 19, 1655–1663 (2011)

    CAS  Article  Google Scholar 

  24. 24

    Oxenoid, K. & Chou, J. J. The structure of phospholamban pentamer reveals a channel-like architecture in membranes. Proc. Natl Acad. Sci. USA 102, 10870–10875 (2005)

    ADS  CAS  Article  Google Scholar 

  25. 25

    Schnell, J. R. & Chou, J. J. Structure and mechanism of the M2 proton channel of influenza A virus. Nature 451, 591–595 (2008)

    ADS  CAS  Article  Google Scholar 

  26. 26

    Van Horn, W. D. et al. Solution nuclear magnetic resonance structure of membrane-integral diacylglycerol kinase. Science 324, 1726–1729 (2009)

    ADS  CAS  Article  Google Scholar 

  27. 27

    Hou, X., Pedi, L., Diver, M. M. & Long, S. B. Crystal structure of the calcium release-activated calcium channel Orai. Science 338, 1308–1313 (2012)

    ADS  CAS  Article  Google Scholar 

  28. 28

    StGelais, C. et al. Determinants of hepatitis C virus p7 ion channel function and drug sensitivity identified in vitro. J. Virol. 83, 7970–7981 (2009)

    CAS  Article  Google Scholar 

  29. 29

    Foster, T. L. et al. Resistance mutations define specific antiviral effects for inhibitors of the hepatitis C virus p7 ion channel. Hepatology 54, 79–90 (2011)

    CAS  Article  Google Scholar 

  30. 30

    Cuello, L. G., Jogini, V., Cortes, D. M. & Perozo, E. Structural mechanism of C-type inactivation in K+ channels. Nature 466, 203–208 (2010)

    ADS  CAS  Article  Google Scholar 

  31. 31

    Pervushin, K., Riek, R., Wider, G. & Wuthrich, K. Attenuated T2 relaxation by mutual cancellation of dipole-dipole coupling and chemical shift anisotropy indicates an avenue to NMR structures of very large biological macromolecules in solution. Proc. Natl Acad. Sci. USA 94, 12366–12371 (1997)

    ADS  CAS  Article  Google Scholar 

  32. 32

    Kay, L. E., Torchia, D. A. & Bax, A. Backbone dynamics of proteins as studied by 15N inverse detected heteronuclear NMR spectroscopy: application to staphylococcal nuclease. Biochemistry 28, 8972–8979 (1989)

    CAS  Article  Google Scholar 

  33. 33

    Szyperski, T., Neri, D., Leiting, B., Otting, G. & Wuthrich, K. Support of 1H NMR assignments in proteins by biosynthetically directed fractional 13C-labeling. J. Biomol. NMR 2, 323–334 (1992)

    CAS  Article  Google Scholar 

  34. 34

    Chou, J. J., Gaemers, S., Howder, B., Louis, J. M. & Bax, A. A simple apparatus for generating stretched polyacrylamide gels, yielding uniform alignment of proteins and detergent micelles. J. Biomol. NMR 21, 377–382 (2001)

    CAS  Article  Google Scholar 

  35. 35

    Sass, H. J., Musco, G., Stahl, S. J., Wingfield, P. T. & Grzesiek, S. Solution NMR of proteins within polyacrylamide gels: Diffusional properties and residual alignment by mechanical stress or embedding of oriented purple membranes. J. Biomol. NMR 18, 303–309 (2000)

    CAS  Article  Google Scholar 

  36. 36

    Tycko, R., Blanco, F. J. & Ishii, Y. Alignment of biopolymers in strained gels: A new way to create detectable dipole-dipole couplings in high-resolution biomolecular NMR. J. Am. Chem. Soc. 122, 9340–9341 (2000)

    CAS  Article  Google Scholar 

  37. 37

    Weigelt, J. Single scan, sensitivity- and gradient-enhanced TROSY for multidimensional NMR experiments. J. Am. Chem. Soc. 120, 10778–10779 (1998)

    CAS  Article  Google Scholar 

  38. 38

    Wu, J., Fan, J. S., Pascal, S. M. & Yang, D. General method for suppression of diagonal peaks in heteronuclear-edited NOESY spectroscopy. J. Am. Chem. Soc. 126, 15018–15019 (2004)

    CAS  Article  Google Scholar 

  39. 39

    Schwieters, C. D., Kuszewski, J., Tjandra, N. & Clore, G. M. The Xplor-NIH NMR molecular structure determination package. J. Magn. Reson. 160, 66–74 (2002)

    Google Scholar 

  40. 40

    Cornilescu, G., Delaglio, F. & Bax, A. Protein backbone angle restraints from searching a database for chemical shift and sequence homology. J. Biomol. NMR 13, 289–302 (1999)

    CAS  Article  Google Scholar 

  41. 41

    Laskowski, R. A., MacArthur, M. W., Moss, D. S. & Thornton, J. W. PROCHECK: a program to check the stereochemical quality of protein structures. J. Appl. Cryst. 26, 283–291 (1993)

    CAS  Article  Google Scholar 

  42. 42

    Plugge, B. et al. A potassium channel protein encoded by chlorella virus PBCV-1. Science 287, 1641–1644 (2000)

    ADS  CAS  Article  Google Scholar 

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We thank R. Sounier for helping with making specific methyl-labelled protein, S. Brueschweiler for helping with ITC measurements, G. Bellot, J. Min and W. Shih for providing DNA nanotube liquid crystal, and K. Oxenoid for discussion. This work was supported by the National Key Project of 973 (2013CB530504) and National Science and Technology Major Project (2012ZX10002-007-003) (to B.S.) and NIH grant GM094608 (to J.J.C.).

Author information




B.O. and J.J.C. conceived the study; B.O. prepared samples; M.J.B. performed EM analysis; J.D. and B.O. performed NMR titration; B.O. and J.J.C. collected and analysed NMR data and determined the structure; S.X., X.Z., W.Y. and B.S. designed and performed functional experiments; J.J.C. wrote the paper and all authors contributed to the editing of the manuscript.

Corresponding authors

Correspondence to Bing Sun or James J. Chou.

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The authors declare no competing financial interests.

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OuYang, B., Xie, S., Berardi, M. et al. Unusual architecture of the p7 channel from hepatitis C virus. Nature 498, 521–525 (2013).

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