The structure of tobacco mosaic virus (TMV) virions and stacked disk aggregates of TMV coat protein (CP) in solution was analyzed by synchrotron-based small-angle X-ray scattering (SAXS) and negative contrast transmission electron microscopy (TEM). TMV CP aggregates had a unique stability but did not have helical symmetry. According to the TEM data, they were stacked disks associated into transversely striated rod-shaped structures 300 to 800 Å long. According to modeling based on the crystallographic model of the 4-layer TMV CP aggregate (PDB: 1EI7), the stacked disks represented hollow cylinders. The calculated SAXS pattern for the disks was compared to the experimental one over the entire measured range. The best correlation with the SAXS data was found for the model with the repeating central pair of discs; the SAXS curves for the stacked disks were virtually identical irrespectively of the protein isolation method. The positions of maxima on the scatter curves could be used as characteristic features of the studied samples; some of the peaks were assigned to the existing elements of the quaternary structure (periodicity of aggregate structure, virion helix pitch). Low-resolution structural data for the repolymerized TMV CP aggregates in solution under conditions similar to natural were produced for the first time. Analysis of such nano-size objects is essential for their application in biomedicine and biotechnology.

中文翻译：

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通过小角度 X 射线散射表征烟草花叶病毒病毒体和溶液中的重聚外壳蛋白聚集体

通过基于同步加速器的小角度 X 射线散射 (SAXS) 和负对比度透射电子显微镜 (TEM) 分析了溶液中烟草花叶病毒 (TMV) 病毒粒子和 TMV 外壳蛋白 (CP) 的堆积盘状聚集体的结构。TMV CP 聚集体具有独特的稳定性，但不具有螺旋对称性。根据 TEM 数据，它们是堆叠的圆盘，连接成 300 到 800 埃长的横向条纹棒状结构。根据基于 4 层 TMV CP 聚集体 (PDB: 1EI7) 的晶体模型的建模，堆叠的圆盘代表空心圆柱体。在整个测量范围内将计算出的圆盘 SAXS 模式与实验模式进行比较。对于具有重复中心圆盘对的模型，发现与 SAXS 数据的最佳相关性；无论蛋白质分离方法如何，堆叠圆盘的 SAXS 曲线几乎相同。散布曲线上最大值的位置可作为研究样本的特征特征；一些峰被指定为四级结构的现有元素（聚集结构的周期性，病毒粒子螺旋节距）。首次获得了在类似于自然条件下的溶液中再聚合 TMV CP 聚集体的低分辨率结构数据。分析这种纳米尺寸的物体对于它们在生物医学和生物技术中的应用至关重要。一些峰被指定为四级结构的现有元素（聚集结构的周期性，病毒粒子螺旋节距）。首次获得了在类似于自然条件下的溶液中再聚合 TMV CP 聚集体的低分辨率结构数据。分析这种纳米尺寸的物体对于它们在生物医学和生物技术中的应用至关重要。一些峰被指定为四级结构的现有元素（聚集结构的周期性，病毒粒子螺旋节距）。首次获得了在类似于自然条件下的溶液中再聚合 TMV CP 聚集体的低分辨率结构数据。分析这种纳米尺寸的物体对于它们在生物医学和生物技术中的应用至关重要。