Crystallization of hepatitis B virus core protein shells: determination ofcryoprotectant conditions and preliminary X-ray characterization

Hepatitis B virus causes liver cirrhosis and hepatocellular cancer and is a major cause of death, particularly in Asia and sub-Saharan Africa. The vir us consists of an inner core or nucleocapsid, which encloses the viral nucl eic acid, with an outer lipid envelope containing surface-antigen proteins. The core protein, when expressed in E. coli, assembles into spherical shel ls containing 180 or 240 subunits, arranged with T = 3 or T = 4 icosahedral symmetry. The C-terminal region of the protein is involved in nucleic acid binding, and deletion of this region does not prevent capsid formation. C- terminally deleted hepatitis B core shells containing 240 subunits have bee n crystallized and data has been collected to 3.6 Angstrom resolution from frozen crystals, using butanediol as a cryoprotectant. The crystals have C2 symmetry with unit-cell parameters a = 538.0, b = 353.0, c = 369.6 Angstro m, beta = 132.3 degrees.