Biophysical characterization of hepatitis C virus core protein: implications for interactions within the virus and host

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Abstract
A primary function of the hepatitis C virus (HCV) core protein is to package the viral genome within a nucleocapsid. In addition, core protein has been shown to interact with more than a dozen cellular proteins, and these interactions have been suggested to play critical roles in HCV pathogenesis. A more complete knowledge of the biophysical properties of the core protein may help to clarify its role in HCV pathogenesis and nucleocapsid assembly and provide a basis for the development of novel anti‐HCV therapies. Here we report that recombinant mature core protein exists as a large multimer in solution under physiological conditions. Far‐UV circular dichroism (CD) experiments showed that the mature core protein contains stable secondary structure. Studies with truncated core protein demonstrated that the C‐terminal region of the core protein is critical for its folding and oligomerization. Intrinsic fluorescence spectroscopy and near‐UV CD analysis indicated that the tryptophan‐rich region (residues 76–113) is largely solvent‐exposed and not likely responsible for multimerization of the mature core protein in vitro.