Department of Protein Science, School of Engineering Sciences in Chemistry, Biotechnology and Health, KTH Royal Institute of Technology, AlbaNova University Center, Stockholm, Sweden.
Department of Chemistry, KTH Royal Institute of Technology, Stockholm, Sweden.
Nat Commun. 2024 May 31;15(1):4670. doi: 10.1038/s41467-024-49111-5.
The major ampullate Spidroin 1 (MaSp1) is the main protein of the dragline spider silk. The C-terminal (CT) domain of MaSp1 is crucial for the self-assembly into fibers but the details of how it contributes to the fiber formation remain unsolved. Here we exploit the fact that the CT domain can form silk-like fibers by itself to gain knowledge about this transition. Structural investigations of fibers from recombinantly produced CT domain from E. australis MaSp1 reveal an α-helix to β-sheet transition upon fiber formation and highlight the helix N4 segment as most likely to initiate the structural conversion. This prediction is corroborated by the finding that a peptide corresponding to helix N4 has the ability of pH-induced conversion into β-sheets and self-assembly into nanofibrils. Our results provide structural information about the CT domain in fiber form and clues about its role in triggering the structural conversion of spidroins during fiber assembly.
主要膨体蛛丝蛋白 1（MaSp1）是牵引丝蜘蛛丝的主要蛋白质。MaSp1 的 C 端（CT）结构域对于自组装成纤维至关重要，但它如何促进纤维形成的细节仍未解决。在这里，我们利用 CT 结构域本身可以形成类丝纤维的事实来获得有关这种转变的知识。对源自 E. australis MaSp1 的重组 CT 结构域形成的纤维的结构研究表明，在纤维形成过程中存在从α-螺旋到β-折叠的转变，并突出了 N4 螺旋段最有可能引发结构转换。这一预测得到了以下发现的证实：与 N4 螺旋相对应的肽具有在 pH 诱导下转化为β-折叠并自组装成纳米原纤维的能力。我们的研究结果提供了纤维形式下 CT 结构域的结构信息，并为其在触发纤维组装过程中蛛丝蛋白结构转换中的作用提供了线索。
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