Xie Qi, On Lee Sea, Vissamsetti Nitya, Guo Sikao, Johnson Margaret E, Fried Stephen D
Department of Chemistry, Johns Hopkins University, 21218, Baltimore, MD, USA.
T. C. Jenkins Department of Biophysics, Johns Hopkins University, 21218, Baltimore, MD, USA.
Angew Chem Int Ed Engl. 2023 Sep 11;62(37):e202305178. doi: 10.1002/anie.202305178. Epub 2023 Aug 3.
Protein-based biomaterials have played a key role in tissue engineering, and additional exciting applications as self-healing materials and sustainable polymers are emerging. Over the past few decades, recombinant expression and production of various fibrous proteins from microbes have been demonstrated; however, the resulting proteins typically must then be purified and processed by humans to form usable fibers and materials. Here, we show that the Gram-positive bacterium Bacillus subtilis can be programmed to secrete silk through its translocon via an orthogonal signal peptide/peptidase pair. Surprisingly, we discover that this translocation mechanism drives the silk proteins to assemble into fibers spontaneously on the cell surface, in a process we call secretion-catalyzed assembly (SCA). Secreted silk fibers form self-healing hydrogels with minimal processing. Alternatively, the fibers retained on the membrane provide a facile route to create engineered living materials from Bacillus cells. This work provides a blueprint to achieve autonomous assembly of protein biomaterials in useful morphologies directly from microbial factories.
基于蛋白质的生物材料在组织工程中发挥了关键作用，并且作为自愈材料和可持续聚合物的其他令人兴奋的应用正在出现。在过去几十年中，已经证明了从微生物中重组表达和生产各种纤维蛋白；然而，随后通常必须由人类对所得蛋白质进行纯化和加工，以形成可用的纤维和材料。在这里，我们表明革兰氏阳性细菌枯草芽孢杆菌可以通过正交信号肽/肽酶对通过其转位子被编程来分泌丝。令人惊讶的是，我们发现这种转运机制驱动丝蛋白在细胞表面自发组装成纤维，我们将这个过程称为分泌催化组装（SCA）。分泌的丝纤维只需最少的加工就能形成自愈水凝胶。或者，保留在膜上的纤维为从芽孢杆菌细胞创建工程化活材料提供了一条简便途径。这项工作提供了一个蓝图，可直接从微生物工厂实现具有有用形态的蛋白质生物材料的自主组装。
