Department of Chemistry, Michigan State University, 578 S. Shaw Lane, East Lansing, MI 48824, USA.
Yale University Medical School, Department of Cell Biology, 333 S. Cedar Street, New Haven, CT 06510, USA.
Chembiochem. 2020 Nov 16;21(22):3192-3196. doi: 10.1002/cbic.202000405. Epub 2020 Aug 14.
Domain-swapping is a mechanism for evolving new protein structure from extant scaffolds, and has been an efficient protein-engineering strategy for tailoring functional diversity. However, domain swapping can only be exploited if it can be controlled, especially in cases where various folds can coexist. Herein, we describe the structure of a domain-swapped trimer of the iLBP family member hCRBPII, and suggest a mechanism for domain-swapped trimerization. It is further shown that domain-swapped trimerization can be favored by strategic installation of a disulfide bond, thus demonstrating a strategy for fold control. We further show the domain-swapped trimer to be a useful protein design template by installing a high-affinity metal binding site through the introduction of a single mutation, taking advantage of its threefold symmetry. Together, these studies show how nature can promote oligomerization, stabilize a specific oligomer, and generate new function with minimal changes to the protein sequence.
结构域交换是一种从现有支架进化新蛋白质结构的机制，也是一种用于调整功能多样性的有效蛋白质工程策略。然而，只有在可以控制的情况下，才能利用结构域交换，特别是在各种折叠可以共存的情况下。本文描述了 iLBP 家族成员 hCRBPII 的结构域交换三聚体的结构，并提出了一种结构域交换三聚体化的机制。进一步表明，通过战略性地安装二硫键可以有利于结构域交换三聚体化，从而展示了一种折叠控制策略。我们进一步通过引入单个突变利用其三倍对称性展示了结构域交换三聚体作为有用的蛋白质设计模板，引入了高亲和力金属结合位点。综上所述，这些研究表明自然界如何通过最小的蛋白质序列变化促进寡聚化、稳定特定的寡聚体并产生新的功能。
