Abstract
Oligomerization of hepatitis C viral envelope proteins E1 and E2 is essential to virus fusion and assembly. Although interactions within the transmembrane (TM) domains of these glycoproteins have proven contributions to the E1/E2 heterodimerization process and consequent infectivity, there is little structural information on this entry mechanism. Here, as a first step towards our long-term goal of understanding the interaction between E1 and E2 TM-domains, we have expressed, purified and characterized E1-TM using structural biomolecular NMR methods. An MBP-fusion expression system yielded sufficient quantities of pure E1-TM, which was solubilized in two membrane-mimicking environments, SDS- and LPPG-micelles, affording samples amenable to NMR studies. Triple resonance assignment experiments and relaxation measurements provided information on the secondary structure and global fold of E1-TM in these environments. In SDS micelles E1-TM adopts a helical conformation, with helical stretches at residues 354-363 and 371-379 separated by a more flexible segment of residues 364-370. In LPPG micelles a helical conformation was observed for residues 354-377 with greater flexibility in the 366-367 dyad, suggesting LPPG provides a more native environment for the peptide. Replacement of key positively charged residue K370 with an alanine did not affect the secondary structure of E1-TM but did change the relative positioning within the micelle of the two helices. These results lay the foundation for structure determination of E1-TM and a molecular understanding of how E1-TM flexibility enhances its interaction with E2-TM during heterodimerization and membrane fusion.
Original language | English |
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Pages (from-to) | 784-792 |
Number of pages | 9 |
Journal | Biochimica et Biophysica Acta - Biomembranes |
Volume | 1838 |
Issue number | 3 |
DOIs | |
State | Published - Mar 2014 |
Bibliographical note
Funding Information:We gratefully acknowledge the ongoing support of Dr. Yoav Peleg (Weizmann Institute of Science, Rehovot, Israel) in design and cloning of E1-TM constructs, and thank Drs. Hugo Gottlieb and Keren Keinan-Adamsky and Mr. Israel Tabakman for technical support at the NMR facility. This work was supported in part by a research grant to J.H.C. by the Israel Science Foundation ( 801/09 ). The 700 MHz spectrometer was purchased with the support of the Converging Technologies Fund.
Funding
We gratefully acknowledge the ongoing support of Dr. Yoav Peleg (Weizmann Institute of Science, Rehovot, Israel) in design and cloning of E1-TM constructs, and thank Drs. Hugo Gottlieb and Keren Keinan-Adamsky and Mr. Israel Tabakman for technical support at the NMR facility. This work was supported in part by a research grant to J.H.C. by the Israel Science Foundation ( 801/09 ). The 700 MHz spectrometer was purchased with the support of the Converging Technologies Fund.
Funders | Funder number |
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Israel Science Foundation | 801/09 |
Keywords
- Envelope glycoproteins
- Hepatitis C virus
- Membrane-associated proteins
- Nuclear magnetic resonance
- Protein structure
- Transmembrane helix