STRUCTURAL GLYCOMICS OF THE E. COLI HOST-PATHOGEN INTERFACE

描述(由申请人提供)：致尿性大肠杆菌(UPEC)对特定宿主表位的识别是启动尿路和肾脏感染的关键过程。这一过程通常是由称为粘附素的碳水化合物结合蛋白(凝集素)介导的，粘附素组装在称为菌毛的毛状细胞外附属物的尖端。粘附素FimH识别宿主尿板上的单甘露糖和多甘露糖表位是尿路感染(UTI)的关键步骤，而PapG识别肾脏中的甘露糖对大肠杆菌肾炎是必不可少的。UPEC菌毛的表达来自菌毛操纵子，该操纵子由一系列基因识别，这些基因编码一个引导者组装平台、一个防止周质组装的伴侣、一个菌毛终止子、一个主要的菌毛亚单位、末端适配子亚基，以及在操纵子末端的粘附素。虽然对FIM和PAP操纵子进行了很好的研究，但还有另外八个UPEC Pilus操纵子，每个操纵子都有自己的粘附素。这项建议利用人多聚糖阵列来确定这八种粘附素的碳水化合物特异性，以及一种外推这些粘附素可能识别哪些宿主组织的计算方法。一个平行的目标是使用高通量的结晶学管道来确定每个粘附素的这一基本宿主-病原体识别事件的结构基础。最后一个关键因素是开发基于细胞的血凝分析，以验证粘附素碳水化合物的特异性及其结构基础。从长远来看，这项工作为开发针对特定粘附素的抗病毒疗法奠定了基础，类似于最近开发的一套针对FimH的甘露糖苷药物，用于治疗尿路感染。 公共卫生相关性：大肠埃希氏菌尿路感染是西方世界最常见的感染。只有五分之一的致尿性大肠杆菌宿主识别蛋白-粘附素得到了很好的研究，但这些蛋白可能是导致尿路和肾脏感染的基本因素。这项建议寻求确定这些未被研究的粘附素如何识别大肠杆菌人类宿主的分子基础，为开发针对这种识别的治疗药物奠定基础。

DESCRIPTION (provided by applicant): Recognition of specific host epitopes by uropathogenic E. coli (UPEC) is a process essential to initiating infection of the urinary tract and kidneys. This process is most often mediated by carbohydrate-binding proteins (lectins) called adhesins that are assembled at the tips of hairlike extracellular appendages called pili. Recognition of mono- and poly-mannose epitopes on host uroplakins by the adhesin FimH is an essential step in urinary tract infection (UTI), while recognition of galabiose in the kidney by PapG is essential to E. coli pyleonephritis. Expression of UPEC pili occurs from pilus operons, which are identifiable by a series of genes encoding an usher assembly platform, a chaperone to prevent periplasmic assembly, a pilus terminator, a major pilus subunit, tip adapter subunits and, invariably at the end of the operon, an adhesin. While the fim and pap operons are well-studied, there are eight additional UPEC pilus operons, each with its own adhesin. This proposal utilizes human glycan arrays to determine the carbohydrate specificity of these eight adhesins as well as a computational method for extrapolating which host tissues these adhesins may recognize. A parallel aim is to determine the structural basis of this fundamental host-pathogen recognition event for each adhesin using a high-throughput crystallography pipeline. A final key element is the development of cell-based hemagglutination assays for validation of adhesin carbohydrate specificity and its structural basis. Long-term, this work sets the stage for development of antivirulence therapies targeting specific adhesins, similar to the recently-developed set of mannoside drugs targeting FimH to cure urinary tract infection. PUBLIC HEALTH RELEVANCE: Escherichia coli urinary tract infection is the most common infection in the Western world. Only one-fifth of the total number of uropathogenic E. coli host-recognition proteins called adhesins are well studied, yet these proteins may represent essential factors in causing urinary tract and kidney infection. This proposal seeks define the molecular basis of how these understudied adhesins recognize E. coli's human host, setting the stage for development of therapeutic drugs that target this recognition.