Structural Transitions and Energy Landscape for Cowpea Chlorotic Mottle Virus Capsid Mechanics from Nanomanipulation in Vitro and in Silico
Structural Transitions and Energy Landscape for Cowpea Chlorotic Mottle Virus Capsid Mechanics from Nanomanipulation in Vitro and in Silico
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DOI：
10.1016/j.bpj.2013.08.032
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发表时间：
2013-10-15
影响因子：
3.4
通讯作者：
Barsegov, Valeri
中科院分区：
文献类型：
--
作者：
Kononova, Olga;Snijder, Joost;Barsegov, Valeri
动植物病毒衣壳的物理特性是衣壳自组装、病毒在细胞外环境中存活及其细胞感染性的重要因素。结合 AFM 实验和对豇豆退绿斑驳病毒衣壳压痕纳米力学亚秒级时间尺度的计算建模表明，衣壳的物理性质是结构的动态和局部特征，其随着压痕深度的变化而变化，并且取决于机械输入的大小和几何形状。在大变形下，豇豆退绿斑驳病毒衣壳转变为塌陷状态，而没有实质性的局部结构改变。该变形状态下的焓变 Delta H-ind =11.5-12.8 MJ/mol 主要是由于大振幅面外激励，这有助于衣壳弯曲；熵变 T Delta S-ind = 5.1-5.8 MJ/mol 是由于蛋白质链的连贯平面内重排导致衣壳硬化。这些模式的直接耦合定义了衣壳压痕动力学的（或）可逆性程度，与其对压缩力的（内）弹性机械响应相关。这张新图片阐明了蛋白质纳米壳独特的物理化学特性如何帮助定义其结构和形态，并确定其病毒的生物功能。
Physical properties of capsids of plant and animal viruses are important factors in capsid self-assembly, survival of viruses in the extracellular environment, and their cell infectivity. Combined AFM experiments and computational modeling on subsecond timescales of the indentation nanomechanics of Cowpea Chlorotic Mottle Virus capsid show that the capsid's physical properties are dynamic and local characteristics of the structure, which change with the depth of indentation and depend on the magnitude and geometry of mechanical input. Under large deformations, the Cowpea Chlorotic Mottle Virus capsid transitions to the collapsed state without substantial local structural alterations. The enthalpy change in this deformation state Delta H-ind =11.5-12.8 MJ/mol is mostly due to large-amplitude out-of-plane excitations, which contribute to the capsid bending; the entropy change T Delta S-ind = 5.1-5.8 MJ/mol is due to coherent in-plane rearrangements of protein chains, which mediate the capsid stiffening. Direct coupling of these modes defines the extent of (ir)reversibility of capsid indentation dynamics correlated with its (in)elastic mechanical response to the compressive force. This emerging picture illuminates how unique physico-chemical properties of protein nanoshells help define their structure and morphology, and determine their viruses' biological function.