School of Optometry and Center for Biophysical Sciences and Engineering, University of Alabama at Birmingham, Birmingham, AL 35294, USA.
Adv Exp Med Biol. 2011;715:175-95. doi: 10.1007/978-94-007-0940-9_11.
Both Gram-negative and Gram-positive pathogens display a multitude of proteins and protein assemblies (pili or fimbriae) on their cell surfaces, which are often used for adherence and initiate colonization and pathogenesis. Adhesive proteins known as MSCRAMMs (microbial surface components recognizing adhesive matrix molecules), anchored by a specific enzyme called sortase in Gram-positive bacteria, target the host's extracellular matrix proteins (ECM) like collagen, fibrinogen and fibronectin. In the past decade, structural analysis by X-ray crystallography has enhanced our understanding of the interactions between MSCRAMMs and the host ECM by revealing several novel structural features that dictate surface protein assembly and the mode of their adhesion to host tissue. The latest focus is on the recently discovered Gram-positive bacterial pili, assembly of which is assisted by yet another specific sortase. Novel features like inter- and intra-molecular isopeptide bonds that facilitate the stability of the pilins, and intra-molecular donor strand complementation to stabilize the adhesin-target interactions are specific to Gram-positive bacteria. This chapter describes and discusses the common structural details between surface proteins and pilins of Gram-positive bacteria and biological implications emanating from these structures.
革兰氏阴性和阳性病原体在其细胞表面都展示出许多蛋白质和蛋白质组装体（菌毛或纤毛），这些蛋白质和蛋白质组装体通常用于黏附和启动定植和发病机制。黏附蛋白被称为 MSCRAMMs（微生物表面成分识别黏附基质分子），在革兰氏阳性菌中由一种称为 sortase 的特定酶锚定，靶向宿主的细胞外基质蛋白（ECM），如胶原蛋白、纤维蛋白原和纤维连接蛋白。在过去的十年中，通过 X 射线晶体学的结构分析增强了我们对 MSCRAMMs 与宿主 ECM 之间相互作用的理解，揭示了几个决定表面蛋白组装及其与宿主组织黏附模式的新结构特征。最新的重点是最近发现的革兰氏阳性细菌菌毛，其组装由另一种特定的 sortase 辅助。一些新特征，如促进菌毛稳定性的分子间和分子内异肽键，以及稳定黏附素-靶标相互作用的分子内供体链互补，是革兰氏阳性细菌所特有的。本章描述并讨论了革兰氏阳性菌表面蛋白和菌毛之间的常见结构细节，以及这些结构产生的生物学意义。
