BINDING OF KLEBSIELLA FIMBRIAE TO RESPIRATORY TISSUE

肺炎克雷伯氏菌的3型菌毛粘附素（MrkD）介导细菌与特定类型胶原蛋白的结合。这种粘附素分子的受体位于组织的基底膜区域，裸露的上皮表面可能存在结合位点。自从K.肺炎是上皮创伤患者呼吸道感染的常见原因，可能由于MrkD粘附素的存在，3型菌毛细菌定殖在这些个体的气道中。在这个提议中，我们描述了实验，我们描述了实验来确定MrkD粘附素在促进呼吸道的体内定殖中的作用。将使用呼吸道感染的鼠模型，并将用稀HCl或六甲基磷酰胺处理动物，以引起粘膜脱落，模拟在受损个体中观察到的类似组织学病变。一株mrkD阳性的克雷伯氏菌。将使用不表达MrkD粘附素的肺炎链球菌和该菌株的衍生物来研究粘附素在定殖中的作用。将对变体MrkD粘附素蛋白进行分子分析，以确定这些分子内的结合结构域。将构建具有显示受体结合特异性的两种不同分子的限定区域的嵌合粘附素。将通过标准技术研究与特定胶原类型的结合。将使用定点诱变来进一步描绘粘附素的胶原结合位点。此外，将检查胶原亚基和片段，以定位整个胶原分子上的受体位点。该材料将用于使用纯化菌毛蛋白以及菌毛细菌的几种结合试验。受体位点的鉴定将允许进一步研究可以抑制易感个体的细菌定殖的合成类似物的开发。

The type 3 fimbrial adhesin (MrkD) of Klebsiella pneumoniae mediates binding of the bacteria to specific types of collagen. The receptors for this adhesin molecule are located in the basement membrane region of tissues, and denuded epithelial surfaces are likely to present binding sites. Since K. pneumoniae is a frequent cause of respiratory infections of patients with epithelial trauma, it is possible that type 3 fimbriate bacteria colonize the airways in these individuals due to the presence of the MrkD adhesin. In this proposal we describe experiments we describe experiments to determine the role of the MrkD adhesin in facilitating colonization, in vivo, of the respiratory tract. A murine model of respiratory infection will be used and the animals will be treated with dilute HCI or hexamethylphosphoramide to cause desquamation of the mucosa to mimic similar histological lesions seen in compromised individuals. An mrkD-positive isolate of K. pneumoniae, and derivatives of this strain that do not express the MrkD adhesin, will be used to investigate the role of the adhesin in colonization. Molecular analysis of variant MrkD adhesin proteins will be performed in order to determine the binding domains within these molecules. Chimeric adhesins possessing defined regions of two different molecules exhibiting receptor binding specificities will be constructed. Binding to specific collagen types will be investigated by standard techniques. Site-directed mutagenesis will be used to further delineate the collagen-binding sites of the adhesin. Also, collagen subunits and fragments will be examined in order to localize the receptor sites on whole collagen molecules. This material will be used in several binding assays using purified fimbrial protein as well as fimbriate bacteria. The identification of receptor sites will allow further investigations into the development of synthetic analogs that could inhibit bacterial colonization of susceptible individuals.