UC San Diego

Hepatitis C virus (HCV) proteins are targets for potential pharmaceutical drugs since there are currently no vaccines against the virus, and drug treatments are expensive and prone to viral resistance. The channel-forming behavior and role of the viroporin p7 from HCV in virus assembly and release make it a promising choice for structure-based drug design. The structures of viroporins have only been successfully solved using nuclear magnetic spectroscopy (NMR). In the case of p7 and other membrane proteins, the lipid environment plays a crucial role in the folding of the protein. Micellar environments have been known to distort membrane protein structures whereas bilayers provide a more native-like membrane environment. The structure of p7 has been solved in two micelle environments, but the distance between the transmembrane helices differ greatly between the two structures. One way to obtain long distance structural restraints in NMR is by obtaining paramagnetic relaxation enhancement (PRE) measurements through the incorporation of a metal-chelating unnatural amino acid (UAA). Here, an UAA with an 8-hydroxyquinoline moiety was successfully incorporated into the transmembrane portion of p7, and intramolecular paramagnetic relaxation enhancements were observed by solution NMR. The next step is to solve the structure of p7 in a lipid bilayer by solid-state NMR. In this research, efforts were made to move from isotropic detergent environments to larger native-like bilayer ones, with the goal of obtaining PREs with the UAA-incorporated p7 by solid-state NMR.