Tanaka Takumi, Terauchi Yuki, Yoshimi Akira, Abe Keietsu
Laboratory of Breeding Engineering for Koji Mold, Department of Biotechnology, Graduate School of Engineering, Osaka University, Suita 565-0871, Japan.
Terrestrial Microbiology and Systematics, Graduate School of Global Environmental Studies, Kyoto University, Kyoto 606-8502, Japan.
Microorganisms. 2022 Jul 25;10(8):1498. doi: 10.3390/microorganisms10081498.
Hydrophobins are small amphipathic proteins conserved in filamentous fungi. In this review, the properties and functions of hydrophobins are comprehensively discussed on the basis of recent findings. Multiple hydrophobins have been identified and categorized in conventional class I and two non-conventional classes. Some hydrophobins can be purified in a water phase without organic solvents. Class I hydrophobins of Aspergilli self-assemble to form amphipathic membranes. At the air-liquid interface, RolA of self-assembles via four stages, and its self-assembled films consist of two layers, a rodlet membrane facing air and rod-like structures facing liquid. The self-assembly depends mainly on hydrophobin conformation and solution pH. Cys4-Cys5 and Cys7-Cys8 loops, disulfide bonds, and conserved Cys residues of RodA-like hydrophobins are necessary for self-assembly at the interface and for adsorption to solid surfaces. AfRodA helps to evade recognition by the host immune system. RodA-like hydrophobins recruit cutinases to promote the hydrolysis of aliphatic polyesters. This mechanism appears to be conserved in and other filamentous fungi, and may be beneficial for their growth. Aspergilli produce various small secreted proteins (SSPs) including hydrophobins, hydrophobic surface-binding proteins, and effector proteins. Aspergilli may use a wide variety of SSPs to decompose solid polymers.
疏水蛋白是丝状真菌中保守的小双亲性蛋白。在本综述中，基于最近的研究结果全面讨论了疏水蛋白的特性和功能。已鉴定出多种疏水蛋白，并将其分为传统的I类和两类非传统类。一些疏水蛋白无需有机溶剂即可在水相中纯化。曲霉属的I类疏水蛋白自组装形成双亲性膜。在气液界面，RolA通过四个阶段自组装，其自组装膜由两层组成，一层是面向空气的小杆状膜，另一层是面向液体的杆状结构。自组装主要取决于疏水蛋白的构象和溶液pH值。类RodA疏水蛋白的Cys4-Cys5和Cys7-Cys8环、二硫键以及保守的半胱氨酸残基对于在界面处自组装和吸附到固体表面是必需的。AfRodA有助于逃避宿主免疫系统的识别。类RodA疏水蛋白招募角质酶以促进脂肪族聚酯的水解。这种机制似乎在曲霉属和其他丝状真菌中是保守的，并且可能对它们的生长有益。曲霉属产生各种小分泌蛋白（SSP），包括疏水蛋白、疏水表面结合蛋白和效应蛋白。曲霉属可能利用多种SSP来分解固体聚合物。
