PDF(Pubmed)
Abstract：
Fibroins\' transition from liquid to solid is fundamental to spinning and underpins the impressive native properties of silk. Herein, we establish a fibroin heavy chain fold for the Silk-I polymorph, which could be relevant for other similar proteins, and explains mechanistically the liquid-to-solid transition of this silk, driven by pH reduction and flow stress. Combining spectroscopy and modelling we propose that the liquid Silk-I fibroin heavy chain (FibH) from the silkworm, Bombyx mori, adopts a newly reported β-solenoid structure. Similarly, using rheology we propose that FibH N-terminal domain (NTD) templates reversible higher-order oligomerization driven by pH reduction. Our integrated approach bridges the gap in understanding FibH structure and provides insight into the spatial and temporal hierarchical self-assembly across length scales. Our findings elucidate the complex rheological behaviour of Silk-I, solutions and gels, and the observed liquid crystalline textures within the silk gland. We also find that the NTD undergoes hydrolysis during standard regeneration, explaining key differences between native and regenerated silk feedstocks. In general, in this study we emphasize the unique characteristics of native and native-like silks, offering a fresh perspective on our fundamental understanding of silk-fibre production and applications.
摘要：
纤维蛋白从液体到固体的转变是纺丝的基础，并支撑着丝绸令人印象深刻的天然特性。在这里，我们为Silk-I多晶型物建立了丝心蛋白重链折叠，这可能与其他类似的蛋白质有关，从机械上解释了这种丝绸从液体到固体的转变，由pH值降低和流动应力驱动。结合光谱学和建模，我们提出来自家蚕的液体丝素蛋白重链（FibH），家蚕,采用新报道的β-螺线管结构。同样，使用流变学，我们建议FibHN末端结构域（NTD）模板可逆的高阶寡聚化由pH降低驱动。我们的集成方法弥合了理解FibH结构的差距，并提供了跨长度尺度的空间和时间分层自组装的见解。我们的发现阐明了Silk-I的复杂流变行为，溶液和凝胶，和丝腺内观察到的液晶纹理。我们还发现NTD在标准再生过程中经历水解，解释天然和再生丝原料之间的主要差异。总的来说,在这项研究中，我们强调了本土和本土丝绸的独特特征，为我们对蚕丝纤维生产和应用的基本理解提供了全新的视角。
