Department of Bioproducts and Biosystems, School of Chemical Engineering, Aalto University, Kemistintie 1, Espoo 02150, Finland.
Academy of Finland Center of Excellence in Life-Inspired Hybrid Materials (LIBER), Aalto University, Kemistintie 1, Espoo 02150, Finland.
Biomacromolecules. 2022 Aug 8;23(8):3142-3153. doi: 10.1021/acs.biomac.2c00179. Epub 2022 Jul 7.
Phase transitions have an essential role in the assembly of nature's protein-based materials into hierarchically organized structures, yet many of the underlying mechanisms and interactions remain to be resolved. A central question for designing proteins for materials is how the protein architecture and sequence affects the nature of the phase transitions and resulting assembly. In this work, we produced 82 kDa (1×), 143 kDa (2×), and 204 kDa (3×) silk-mimicking proteins by taking advantage of protein ligation by SpyCatcher/Tag protein-peptide pair. We show that the three silk proteins all undergo a phase transition from homogeneous solution to assembly formation. In the assembly phase, a length- and concentration-dependent transition between two distinct assembly morphologies, one forming aggregates and another coacervates, exists. The coacervates showed properties that were dependent on the protein size. Computational modeling of the proteins by a bead-spring model supports the experimental results and provides us a possible mechanistic origin for the assembly transitions based on architectures and interactions.
相变在自然界中基于蛋白质的材料组装成具有层次结构的结构中起着重要作用，但许多潜在的机制和相互作用仍有待解决。为材料设计蛋白质的一个核心问题是蛋白质结构和序列如何影响相变的性质以及由此产生的组装。在这项工作中，我们利用 SpyCatcher/Tag 蛋白-肽对的蛋白连接，生产了 82 kDa（1×）、143 kDa（2×）和 204 kDa（3×）的丝模拟蛋白。我们表明，这三种丝蛋白都经历了从均相溶液到组装形成的相变。在组装相中，存在两种不同组装形态之间的长度和浓度依赖性转变，一种形成聚集体，另一种形成凝聚物。凝聚物表现出依赖于蛋白质大小的性质。通过珠子-弹簧模型对蛋白质进行的计算建模支持了实验结果，并为我们提供了基于结构和相互作用的组装转变的可能的机械起源。
