National Centre for Biological Sciences, Tata Institute of Fundamental Research, Bengaluru, 560065, India.
Sastra University, Thanjavur, 613402, India.
Nat Commun. 2019 Jan 28;10(1):452. doi: 10.1038/s41467-019-08295-x.
Domain swapping is the process by which identical monomeric proteins exchange structural elements to generate dimers/oligomers. Although engineered domain swapping is a compelling strategy for protein assembly, its application has been limited due to the lack of simple and reliable design approaches. Here, we demonstrate that the hydrophobic five-residue 'cystatin motif' (QVVAG) from the domain-swapping protein Stefin B, when engineered into a solvent-exposed, tight surface loop between two β-strands prevents the loop from folding back upon itself, and drives domain swapping in non-domain-swapping proteins. High-resolution structural studies demonstrate that engineering the QVVAG stretch independently into various surface loops of four structurally distinct non-domain-swapping proteins enabled the design of different modes of domain swapping in these proteins, including single, double and open-ended domain swapping. These results suggest that the introduction of the QVVAG motif can be used as a mutational approach for engineering domain swapping in diverse β-hairpin proteins.
结构域交换是相同单体蛋白交换结构元件以生成二聚体/多聚体的过程。尽管工程化的结构域交换是一种用于蛋白质组装的引人注目的策略，但由于缺乏简单可靠的设计方法，其应用受到限制。在这里，我们证明了来自 Stefin B 结构域交换蛋白的疏水五残基“半胱氨酸蛋白酶抑制剂基序”（QVVAG），当被工程改造到两个β-链之间溶剂暴露的紧密表面环中时，可防止环自身折叠，并在非结构域交换蛋白中驱动结构域交换。高分辨率结构研究表明，将 QVVAG 延伸独立地工程改造到四个结构不同的非结构域交换蛋白的各种表面环中，可在这些蛋白中设计不同的结构域交换模式，包括单、双和开放式结构域交换。这些结果表明，引入 QVVAG 基序可作为用于工程化不同β-发夹蛋白结构域交换的突变方法。
