Laboratory of Self-Organizing Soft Matter, Laboratory of Macromolecular and Organic Chemistry, Laboratory of Physical Chemistry, Department of Chemical Engineering and Chemistry, Institute for Complex Molecular Systems.
Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario K7L 3N6, Canada.
Trends Microbiol. 2019 May;27(5):453-467. doi: 10.1016/j.tim.2018.12.003. Epub 2019 Jan 15.
Gram-negative bacteria produce repeats-in-toxin adhesion proteins (RTX adhesins) to facilitate microbial adhesion. These large, multidomain proteins share a common architecture comprised of four regions. First to emerge from the bacterium, C terminal end leading, is the RTX export sequence that directs the protein through the type 1 secretion system (T1SS). This is followed by the ligand-binding region responsible for host adhesion and cohesion, which contains diverse ligand-binding domains. These serve a zip code function to direct bacteria to a particular environmental niche. Thereafter is a large extension region consisting of tens to hundreds of tandem bacterial immunoglobulin-like (BIg) domains, whose function is to extend the reach of the ligand-binding domains away from the bacterial surface. Lastly, there is a conserved N terminal cell-membrane-anchor region that retains the adhesin within the secretion system. This is also a site of in situ proteolysis, when nutrients are scarce, that enables the bacterium to leave the biofilm. In this review, the four regions of RTX adhesins are presented in the order in which they emerge from the cell during synthesis and retention.
革兰氏阴性菌产生重复毒素粘附蛋白 (RTX 粘附素) 以促进微生物粘附。这些大型的多结构域蛋白具有共同的结构，由四个区域组成。首先从细菌中出现的是 C 末端先导的 RTX 出口序列，该序列将蛋白质引导通过 I 型分泌系统 (T1SS)。其次是负责宿主粘附和凝聚的配体结合区域，其中包含多种配体结合结构域。这些结构域起到邮政编码的作用，将细菌引导到特定的环境小生境。然后是一个由数十到数百个串联的细菌免疫球蛋白样 (BIg) 结构域组成的大扩展区域，其功能是将配体结合结构域的作用范围从细菌表面延伸出去。最后，有一个保守的 N 端细胞膜锚定区域，它使粘附素保留在分泌系统中。这也是在营养物质匮乏时原位蛋白水解的部位，使细菌能够离开生物膜。在这篇综述中，按照在合成和保留过程中从细胞中出现的顺序呈现了 RTX 粘附素的四个区域。
