Exploiting simple types of symmetry common to many natural protein oligomers as a starting point, several recent studies have succeeded in engineering complex self-assembling protein architectures reminiscent but distinct from those evolved in the natural world. Designing symmetric protein cages with a wide range of properties has been of particular interest for potential applications in the fields of medicine, energy, imaging, and more. In this study we genetically fused three naturally symmetric protein components together-a pentamer, trimer, and dimer-in a fashion designed to create a self-assembling icosahedral protein cage built from 60 copies of the protein subunit. The connection between the pentamer and dimer was based on a continuous shared α helix in order to control the relative orientation of those components. Following selection of suitable components by computational methods, a construct with favorable design properties was tested experimentally. Negative stain electron microscopy and solution-state methods indicated successful formation of a 60-subunit icosahedral cage, 2.5 MDa in mass and 30 nm in diameter. Diverse experimental studies also suggested substantial degrees of flexibility and asymmetric deformation of the assembled particle in solution. The results add further examples of successes and challenges in designing atomically precise protein materials.

中文翻译：

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由包含三个不同的对称元素的双融合蛋白形成的二十面体蛋白笼的设计和表征。

以许多天然蛋白质寡聚物常见的简单对称类型为起点，最近的几项研究成功地工程化了复杂的自组装蛋白质结构，使人联想到自然界中演化出来的结构，但与之不同。设计具有广泛特性的对称蛋白笼对于在医学，能源，成像等领域的潜在应用特别感兴趣。在这项研究中，我们将三种自然对称的蛋白质成分（五聚体，三聚体和二聚体）遗传融合在一起，这种方式旨在创建由60个蛋白质亚基构成的自组装二十面体蛋白质笼。五聚体和二聚体之间的连接基于连续共享的α螺旋，以便控制这些组件的相对方向。通过计算方法选择合适的组件后，对具有良好设计特性的构建体进行了实验测试。负染色电子显微镜和溶液状态方法表明成功形成了60个亚单位的二十面体笼，质量为2.5 MDa，直径为30 nm。各种实验研究还表明，溶液中组装好的颗粒具有很大程度的柔韧性和不对称变形。结果为设计原子精确的蛋白质材料提供了成功和挑战的更多示例。各种实验研究还表明，溶液中组装好的颗粒具有很大程度的柔韧性和不对称变形。结果为设计原子精确的蛋白质材料提供了成功和挑战的更多示例。各种实验研究还表明，溶液中组装好的颗粒具有很大程度的柔韧性和不对称变形。结果为设计原子精确的蛋白质材料提供了成功和挑战的更多示例。