Natural spider silk with extraordinary mechanical properties is typically spun from more than one type of spidroin. Although the main components of various spider silks have been widely studied, little is known about the molecular role of the minor silk components in spidroin self-assembly and fiber formation. Here, we show that the minor component of spider eggcase silk, TuSp2, not only accelerates self-assembly but remarkably promotes molecular chain alignment of spidroins upon physical shearing. NMR structure of the repetitive domain of TuSp2 reveals that its dimeric structure with unique charged surface serves as a platform to recruit different domains of the main eggcase component TuSp1. Artificial fiber spun from the complex between TuSp1 and TuSp2 minispidroins exhibits considerably higher strength and Young’s modulus than its native counterpart. These results create a framework for rationally designing silk biomaterials based on distinct roles of silk components.

具有非凡机械性能的天然蜘蛛丝通常由不止一种蜘蛛丝纺制而成。尽管各种蜘蛛丝的主要成分已被广泛研究，但很少有人了解次要丝成分在蜘蛛丝蛋白自组装和纤维形成中的分子作用。在这里，我们表明蜘蛛蛋壳丝的微量成分 TuSp2 不仅加速了自组装，而且在物理剪切时显着促进了蜘蛛蛋白的分子链排列。TuSp2 重复结构域的 NMR 结构表明，其具有独特带电表面的二聚体结构可作为招募主要蛋壳成分 TuSp1 不同结构域的平台。从 TuSp1 和 TuSp2 minispidroins 之间的复合物纺成的人造纤维比其天然纤维表现出更高的强度和杨氏模量。这些结果为基于丝成分的不同作用合理设计丝生物材料创建了一个框架。