BINDING OF KLEBSIELLA FIMBRIAE TO RESPIRATORY TISSUE

肺炎克雷伯菌的3型菌毛粘附素(MRKD)介导细菌与特定类型的胶原结合。这种粘附素分子的受体位于组织的基底膜区域，剥离的上皮表面可能存在结合部位。由于肺炎克雷伯菌是上皮性创伤患者呼吸道感染的常见原因，由于MRKD粘附素的存在，3型菌毛细菌可能在这些人的呼吸道中定植。在这项建议中，我们描述了实验，我们描述了确定MRKD粘附素在促进体内呼吸道定植中的作用的实验。将使用小鼠呼吸道感染的模型，这些动物将被稀释的盐酸或六甲基磷酰胺治疗，以导致粘膜脱屑，以模仿受损个体的类似组织学损害。肺炎克雷伯菌mrkD阳性分离株及其不表达mrkD粘附素的衍生物将被用于研究粘附素在定植中的作用。将对变异的MRKD粘附素蛋白进行分子分析，以确定这些分子中的结合域。具有两个不同分子的特定区域的嵌合型粘附素将被构建出来，这些分子表现出受体结合的特异性。结合特定类型的胶原蛋白将通过标准技术进行研究。定点突变将被用来进一步描述粘附素的胶原结合位点。此外，还将检查胶原亚单位和片段，以确定整个胶原蛋白分子上的受体位置。这种材料将用于使用纯化的菌毛蛋白以及菌毛细菌的几种结合分析。受体位置的鉴定将有助于进一步研究合成类似物，以抑制易感个体的细菌定植。

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.