Lee Lye Siang, Brunk Nicholas, Haywood Daniel G, Keifer David, Pierson Elizabeth, Kondylis Panagiotis, Wang Joseph Che-Yen, Jacobson Stephen C, Jarrold Martin F, Zlotnick Adam
Molecular and Cellular Biochemistry Department, Indiana University, Bloomington, Indiana, 47405.
Intelligent Systems Engineering Department, Bloomington, Indiana, 47405.
Protein Sci. 2017 Nov;26(11):2170-2180. doi: 10.1002/pro.3265. Epub 2017 Sep 16.
Hepatitis B virus (HBV) core protein is a model system for studying assembly and disassembly of icosahedral structures. Controlling disassembly will allow re-engineering the 120 subunit HBV capsid, making it a molecular breadboard. We examined removal of subunits from partially crosslinked capsids to form stable incomplete particles. To characterize incomplete capsids, we used two single molecule techniques, resistive-pulse sensing and charge detection mass spectrometry. We expected to find a binomial distribution of capsid fragments. Instead, we found a preponderance of 3 MDa complexes (90 subunits) and no fragments smaller than 3 MDa. We also found 90-mers in the disassembly of uncrosslinked HBV capsids. 90-mers seem to be a common pause point in disassembly reactions. Partly explaining this result, graph theory simulations have showed a threshold for capsid stability between 80 and 90 subunits. To test a molecular breadboard concept, we showed that missing subunits could be refilled resulting in chimeric, 120 subunit particles. This result may be a means of assembling unique capsids with functional decorations.
乙型肝炎病毒（HBV）核心蛋白是研究二十面体结构组装与拆卸的一个模型系统。控制拆卸过程将使重新设计由120个亚基组成的HBV衣壳成为可能，使其成为一个分子实验平台。我们研究了从部分交联的衣壳中去除亚基以形成稳定的不完全颗粒。为了表征不完全衣壳，我们使用了两种单分子技术，即电阻脉冲传感和电荷检测质谱法。我们预期会发现衣壳片段的二项分布。然而，我们发现主要是3兆道尔顿的复合物（90个亚基），且没有小于3兆道尔顿的片段。我们还在未交联的HBV衣壳拆卸过程中发现了90聚体。90聚体似乎是拆卸反应中一个常见的停顿点。图论模拟部分解释了这一结果，其表明衣壳稳定性在80至90个亚基之间存在一个阈值。为了测试分子实验平台的概念，我们证明缺失的亚基可以重新填充，从而形成嵌合的、由120个亚基组成的颗粒。这一结果可能是一种组装带有功能性修饰的独特衣壳的方法。
