STRUCTURE OF ORAL BACTERIAL ADHESINS

描述（由申请人提供）：口腔内有500多种革兰氏阳性和革兰氏阴性细菌，它们存在于一个称为生物膜的复杂生态系统中。生物膜的形成是由口腔链球菌附着在口腔表面获得的唾液膜上引起的。随着生物膜的发育和成熟，与牙周病相关的晚期细菌定植体附着在现有生物膜上的条件变得有利。细菌与获得性唾液膜或宿主受体的粘附是生物膜形成、细菌定植和感染的关键步骤。细菌粘附是由毛状和非毛状粘附素介导的，毛状和非毛状粘附素是显示在含有受体结合域的细菌表面的蛋白质附属物。叶缘黏附素形成由单个亚基或多个亚基的多个拷贝组成的长丝状结构。副鳗的长毛由多个Fap1亚基组成，Fap1亚基对生物膜的形成至关重要。最近在其他链球菌家族成员中发现了Fap-1同源物。非毛状粘附素形成由单个亚基或少量相同亚基组成的较短结构，特异性折叠以暴露远端受体结合域。放线菌利用特异性的非毛黏附素粘附和侵入上皮细胞，并与细胞外基质蛋白相互作用。EmaA （Extracellular matrix protein adhesion - a）是一种新发现的放线菌属（放线菌属）的非毛状粘连蛋白，参与与宿主组织中的胶原蛋白和微管蛋白结合。EmaA是一种多聚体自转运蛋白，通过3或4个亚基（总分子质量为600-800 kDa）的寡聚化在细菌细胞表面形成结构。这种粘附素和/或粘附素/受体复合物的结构信息是未知的。由于抗生素耐药生物数量的增加，粘附素/受体相互作用的详细3D结构信息对于下一代治疗方法的开发非常重要。然而，迄今为止，关于口腔细菌的结构信息缺乏。在这个应用中，我们建议确定粘附素和粘附素/受体复合物的3D结构，这两个早期细菌定植体（Fap-1）和晚期定植体（EmaA）对于深入了解致病过程的不同阶段至关重要。我们将使用电子显微镜和图像处理的新技术来进行这些研究。我们的工作将为这些粘附素和各自的粘附素/受体复合物提供第一个3D结构数据。

DESCRIPTION (provided by applicant): The oral cavity is inhabited by more than 500 species of Gram-positive and Gram-negative bacteria, which exist in a complex ecosystem referred to as a biofilm. Biofilm formation is initiated by the attachment of oral streptococci to the acquired salivary pellicle coating the surfaces of the oral cavity. As the biofilm develops and matures, conditions become propitious for the attachment of the late bacterial colonizers, which are associated with periodontal disease to the existing biofilm. Bacterial adhesion to the acquired salivary pellicle or to host receptors is a crucial step for biofilm formation, bacterial colonization and infection. Bacterial adhesion is mediated by fimbrial and non-fimbrial adhesins, which are proteinaceous appendages displayed on the surface of bacteria containing the receptor binding domains. Fimbrial adhesins form long filamentous structures composed of multiple copies of either a single subunit or multiple subunits. The long-fimbriae of S. parasanguis are composed of multiple subunits of Fap1 (fimbriae-associated protein 1), which are crucial for biofilm formation. Fap-1 homologues have recently been found in other streptococcal family members. Non-fimbrial adhesins form shorter structures comprised of either a single subunit or a small number of identical subunits specifically folding to expose the receptor binding domain at the distal-end. A. actinomycetemcomitans uses specific non-fimbrial adhesins to adhere to and invade into epithelial cells as well as interacting with extracellular matrix proteins. EmaA (Extracellular matrix protein adhesin-A) is a newly discovered non-fimbrial adhesin of A. actinomycetemcomitans involved in binding to collagen and tubulin in the host tissue. EmaA is a multimeric autotransporter protein, which forms structures on the bacterial cell surface by oligomerization of either 3 or 4 subunits (total molecular mass of 600-800 kDa). Structural information on this adhesin and/or the adhesin/receptor complexes is unknown. Detailed 3D structural information on adhesin/receptor interactions is extremely important for the development of next generation therapeutics due to the increase number of antibiotic resistant organisms. To date, however, there is a paucity of structural information regarding oral bacteria. In this application, we propose to determine the 3D structure of the adhesins and adhesin/receptor complexes of both an early bacterial colonizer (Fap-1) and a late colonizer (EmaA) essential to gain insights into the different stages of the pathogenic process. We will carry out these studies using novel techniques of electron microscopy and image processing. Our work will provide the first 3D structural data for these adhesins and the respective adhesin/receptor complexes. PROJECT NARRATIVE: The human oral cavity is inhabited by more than 500 species of bacteria, which are responsible for causing oral and serious extra-oral systemic diseases. Bacterial adhesion, mediated by adhesins on the cell surface, is a crucial step for biofilm formation, colonization, and infection. We will determine the 3D structure of the adhesins and adhesin/receptor complexes, which is essential to gain insights into the different stages of the pathogenic process.