Abstract
HBV causes chronic infections that can lead to severe liver disease, yet current treatments rarely achieve a cure. The HBV capsid is a critical therapeutic target, but structural insights have largely relied on E. coli-derived particles lacking native modifications. Here, we present near-atomic resolution cryo-electron microscopy (EM) structures of HBV capsids purified from human embryonic kidney (HEK-293T) cells, capturing authentic architecture and post-translational modifications. A hydrophobic pocket at the intradimer interface harbors lipid-like densities corresponding to stearic and palmitic acids, confirmed by gas chromatography-mass spectrometry. Molecular dynamics simulations revealed that pocket accessibility is regulated by rotamer states of Lys96, Phe97, and Gln99, supporting an induced fit model of fatty acid binding. Reduced phosphorylation and increased RNA content further modulate capsid conformation and pocket openness. These findings highlight the dynamic regulation of HBV capsid structure and provide a framework for understanding how capsid conformational dynamics contribute to viral assembly and envelopment.
Keywords:
capsid assembly; capsid protein; cryo-EM; empty capsid; fatty acid; hepatitis B virus; hydrophobic pocket; molecular dynamics simulations; pocket factor; single particle analysis.