School of Molecular Bioscience, University of Sydney, NSW 2006, Australia.
J Mol Biol. 2013 Jan 23;425(2):244-56. doi: 10.1016/j.jmb.2012.10.021. Epub 2012 Nov 5.
The hydrophobin DewA from the fungus Aspergillus nidulans is a highly surface-active protein that spontaneously self-assembles into amphipathic monolayers at hydrophobic:hydrophilic interfaces. These monolayers are composed of fibrils that are a form of functional amyloid. While there has been significant interest in the use of DewA for a variety of surface coatings and as an emulsifier in biotechnological applications, little is understood about the structure of the protein or the mechanism of self-assembly. We have solved the solution NMR structure of DewA. While the pattern of four disulfide bonds that is a defining feature of hydrophobins is conserved, the arrangement and composition of secondary-structure elements in DewA are quite different to what has been observed in other hydrophobin structures. In addition, we demonstrate that DewA populates two conformations in solution, both of which are assembly competent. One conformer forms a dimer at high concentrations, but this dimer is off-pathway to fibril formation and may represent an assembly control mechanism. These data highlight the structural differences between fibril-forming hydrophobins and those that form amorphous monolayers. This work will open up new opportunities for the engineering of hydrophobins with novel biotechnological applications.
真菌构巢曲霉中的亲水性蛋白 DewA 是一种高度表面活性的蛋白质，可在疏水性和亲水性界面自发自组装成两亲单层。这些单层由纤维组成，纤维是功能性淀粉样蛋白的一种形式。尽管人们对 DewA 在各种表面涂层中的应用以及在生物技术应用中的乳化剂作用产生了浓厚的兴趣，但对该蛋白质的结构或自组装机制却知之甚少。我们已经解决了 DewA 的溶液 NMR 结构。尽管维持了疏水性蛋白的四个二硫键模式，但 DewA 中二级结构元素的排列和组成与其他疏水性蛋白结构观察到的完全不同。此外，我们证明 DewA 在溶液中存在两种构象，这两种构象都具有组装能力。一种构象在高浓度下形成二聚体，但这种二聚体偏离了纤维形成途径，可能代表组装控制机制。这些数据突出了形成纤维的疏水性蛋白和形成无定形单层的疏水性蛋白之间的结构差异。这项工作将为具有新型生物技术应用的疏水性蛋白的工程设计开辟新的机会。
