ACIB GmbH c/o Institute of Molecular Biosciences, Humboldstraße 50, III, University of Graz, A-8010, Graz, Austria.
Adv Exp Med Biol. 2011;715:143-58. doi: 10.1007/978-94-007-0940-9_9.
Trimeric autotransporter adhesins (TAAs) are a family of secreted Gram-negative bacterial outer membrane (OM) proteins. These obligate homotrimeric proteins share a common molecular organisation, consisting of a N-terminal "passenger" domain followed by a C-terminal translocation unit/membrane anchor. All described TAAs act as adhesins. The passenger domain is responsible for specific adhesive and other activities of the protein and has a modular architecture. Its globular head domain(s), where ligands often bind, are projected away from the bacterial surface by an extended triple α-helical coiled coil stalk attached to the β-barrel anchor. The head domains appear to be constructed from a limited set of subdomains. The β-barrel anchor is the only part of the protein strictly conserved between family members. It appears that the extracellular export of the passenger does not require an external energy source or auxiliary proteins, though recent data indicate that an OM complex (the Bam complex) is involved in passenger domain secretion. The ability to bind to a variety of host molecules such as collagen, fibronectin, laminin or cell surface receptors via a structurally diverse elements suggests that TAAs have evolved a unique mechanism which closely links structure to folding and function.
三聚体自转运黏附素（TAAs）是一类分泌型革兰氏阴性菌外膜（OM）蛋白。这些必需的三聚体蛋白具有共同的分子结构，由 N 端“过客”结构域和 C 端转位单元/膜锚组成。所有描述的 TAAs 都作为黏附素发挥作用。过客结构域负责蛋白的特定黏附和其他活性，具有模块化的结构。其球状头部结构域（配体通常结合于此）通过与 β 桶锚相连的延伸三螺旋卷曲螺旋茎从细菌表面伸出。头部结构域似乎由一组有限的亚结构域组成。β 桶锚是家族成员之间严格保守的唯一部分。尽管最近的数据表明一个 OM 复合物（Bam 复合物）参与了过客结构域的分泌，但过客的细胞外输出似乎不需要外部能源或辅助蛋白。通过结构多样的元件与多种宿主分子（如胶原蛋白、纤维连接蛋白、层粘连蛋白或细胞表面受体）结合的能力表明，TAAs 已经进化出一种独特的机制，将结构与折叠和功能紧密联系在一起。
