Department of Molecular and Cellular Biochemistry , Indiana University , Bloomington , Indiana 47405 , United States.
Department of Chemistry , Indiana University , Bloomington , Indiana 47405 , United States.
ACS Chem Biol. 2018 Aug 17;13(8):2114-2120. doi: 10.1021/acschembio.8b00283. Epub 2018 Jul 6.
The Hepatitis B Virus (HBV) core protein homodimers self-assemble to form an icosahedral capsid that packages the viral genome. Disassembly occurs in the nuclear basket to release the mature genome to the nucleus. Small molecules have been developed that bind to a pocket at the interdimer interface to accelerate assembly and strengthen interactions between subunits; these are under development as antiviral agents. Here, we explore the role of the dimer-dimer interface by mutating sites in the drug-binding pocket to cysteine and examining the effect of covalently linking small molecules to them. We find that ligands bound to the pocket may trigger capsid disassembly in a dose-dependent manner. This result indicates that, at least transiently, the pocket adopts a destabilizing conformation. We speculate that this pocket also plays a role in virus disassembly and genome release by binding ligands that are incompatible with virus stability, "unwanted guests." Investigating protein-protein interactions, especially large protein polymers, offers new and unique challenges. By using an engineered addressable thiol, we provide a means to examine the effects of modifying an interface without requiring drug-like properties for the ligand.
乙型肝炎病毒 (HBV) 核心蛋白同源二聚体自组装形成二十面体衣壳，将病毒基因组包装在内。衣壳在核篮中解体，将成熟的基因组释放到细胞核中。已经开发出一些小分子，它们与二聚体界面的口袋结合，以加速组装并增强亚基之间的相互作用；这些小分子正在作为抗病毒药物开发。在这里，我们通过将药物结合口袋中的位点突变为半胱氨酸来探索二聚体-二聚体界面的作用，并研究将小分子共价连接到这些位点的效果。我们发现，结合到口袋中的配体可能会以剂量依赖的方式触发衣壳解体。这一结果表明，至少在瞬时情况下，口袋会采用一种不稳定的构象。我们推测，这个口袋也通过结合与病毒稳定性不兼容的配体（“不速之客”）来发挥作用，从而参与病毒解体和基因组释放。研究蛋白质-蛋白质相互作用，尤其是大型蛋白质聚合物，带来了新的和独特的挑战。通过使用工程化的可寻址巯基，我们提供了一种在不需要配体具有类似药物特性的情况下检查修饰界面效果的方法。
