Electron Microscopy, Groningen Biomolecular Sciences and Biotechnology Institute (GBB), University of Groningen, Nijenborgh 7, 9747 AG Groningen, The Netherlands.
J Struct Biol. 2013 Nov;184(2):301-9. doi: 10.1016/j.jsb.2013.08.013. Epub 2013 Sep 5.
Chaplins are small, secreted proteins of streptomycetes that play instrumental roles in the formation of aerial hyphae and attachment of hyphae to surfaces. Here we show that the purified proteins self-assemble at a water/air interface into an asymmetric and amphipathic protein membrane that has an amyloid nature. Cryo-tomography reveals that the hydrophilic surface is relatively smooth, while the hydrophobic side is highly structured and characterized by the presence of small fibrils, which are similar to those observed on the surfaces of aerial hyphae. Interestingly, our work also provides evidence that chaplins in solution assemble into amyloid fibrils with a distinct morphology. These hydrophilic fibrils strongly resemble the structures known to be involved in attachment of Streptomyces hyphae to surfaces. These data for the first time show the assembly of bacterial proteins into two distinct amyloid structures that have different and relevant functions in vivo.
芽胞杆菌素是链霉菌中分泌的小蛋白，在气生菌丝的形成和菌丝附着在表面上起着重要作用。在这里，我们表明，纯化的蛋白质在水/气界面处自组装成具有淀粉样性质的不对称两亲性蛋白质膜。冷冻断层扫描显示，亲水面相对光滑，而疏水面高度结构化，存在小纤维，与气生菌丝表面观察到的纤维相似。有趣的是，我们的工作还提供了证据，表明溶液中的芽胞杆菌素组装成具有独特形态的淀粉样纤维。这些亲水纤维非常类似于已知参与链霉菌菌丝附着在表面的结构。这些数据首次表明，细菌蛋白组装成两种不同的淀粉样结构，它们在体内具有不同且相关的功能。
