The Unusual Transmembrane Partition of the Hexameric Channel of the Hepatitis C Virus

Wen Chen; Jyoti Dev; Julija Mezhyrova; Liqiang Pan; Alessandro Piai; James J Chou

doi:10.1016/j.str.2018.02.011

The Unusual Transmembrane Partition of the Hexameric Channel of the Hepatitis C Virus

Structure. 2018 Apr 3;26(4):627-634.e4. doi: 10.1016/j.str.2018.02.011. Epub 2018 Mar 15.

Authors

Wen Chen¹, Jyoti Dev¹, Julija Mezhyrova², Liqiang Pan¹, Alessandro Piai¹, James J Chou³

Affiliations

¹ Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115, USA.
² Institute of Biophysical Chemistry, Centre for Biomolecular Magnetic Resonance, J.W. Goethe-University, Frankfurt am Main, Germany.
³ Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115, USA; State Key Laboratory of Molecular Biology, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, University of Chinese Academy of Sciences, Shanghai 201203, China. Electronic address: [email protected].

Abstract

The p7 protein of the hepatitis C virus (HCV) can oligomerize in membrane to form cation channels. Previous studies showed that the channel assembly in detergent micelles adopts a unique flower-shaped oligomer, but the unusual architecture also presented problems for understanding how this viroporin resides in the membrane. Moreover, the oligomeric state of p7 remains controversial, as both hexamer and heptamer have been proposed. Here we address the above issues using p7 reconstituted in bicelles that mimic a lipid bilayer. We found, using a recently developed oligomer-labeling method, that p7 forms hexamers in the bicelles. Solvent paramagnetic relaxation enhancement analyses showed that the bilayer thickness around the HCV ion channel is substantially smaller than expected, and thus a significant portion of the previously assigned membrane-embedded region is solvent exposed. Our study provides an effective approach for characterizing the transmembrane partition of small ion channels in near lipid bilayer environment.

Keywords: HCV p7 channel; NMR; bicelle; lipophilic PRE; membrane partition; oligomeric state; solvent PRE.

Publication types

Research Support, N.I.H., Extramural
Research Support, Non-U.S. Gov't

MeSH terms

Amino Acid Motifs
Binding Sites
Biomimetic Materials / chemistry*
Biomimetic Materials / metabolism
Cloning, Molecular
Crystallography, X-Ray
Dimyristoylphosphatidylcholine / chemistry*
Dimyristoylphosphatidylcholine / metabolism
Escherichia coli / genetics
Escherichia coli / metabolism
Gene Expression
Genetic Vectors / chemistry
Genetic Vectors / metabolism
Hepacivirus / chemistry*
Hepacivirus / metabolism
Ion Channels / chemistry*
Ion Channels / genetics
Ion Channels / metabolism
Lipid Bilayers / chemistry*
Lipid Bilayers / metabolism
Models, Molecular
Phospholipid Ethers / chemistry*
Phospholipid Ethers / metabolism
Protein Binding
Protein Conformation, alpha-Helical
Protein Interaction Domains and Motifs
Protein Multimerization
Recombinant Fusion Proteins / chemistry
Recombinant Fusion Proteins / genetics
Recombinant Fusion Proteins / metabolism
Viral Proteins / chemistry*
Viral Proteins / genetics
Viral Proteins / metabolism

Substances

1,2-dihexadecyl-sn-glycero-3-phosphocholine
Ion Channels
Lipid Bilayers
Phospholipid Ethers
Recombinant Fusion Proteins
Viral Proteins
p7 protein, Hepatitis C virus
Dimyristoylphosphatidylcholine

Grants and funding

R01 GM116898/GM/NIGMS NIH HHS/United States