Novel Type IV Pili of Enterohemorrhagic E. coli O157:H7

肠出血性大肠杆菌 O157:H7 的新型 IV 菌毛

• 批准号: 6811345
• 负责人: JORGE A GIRON
• 金额: $ 28.33万
• 依托单位: UNIVERSITY OF ARIZONA
• 依托单位国家: 美国
• 财政年份: 2004
• 资助国家: 美国
• 起止时间: 2004-09-30 至 2006-09-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6811345
• 关键词: Escherichia coli 0157:H7; adhesin; bacteria infection mechanism; bacterial genetics; biosynthesis; bioterrorism /chemical warfare; cell adhesion; cell component structure /function; colitis; diarrhea; electron microscopy; emerging infectious disease; endopeptidases; epithelium; gene expression; genetic techniques; hemolytic anemia; hemorrhage; host organism interaction; laboratory rabbit; pilus; protein structure function; renal failure; shiga toxin; tissue /cell culture; virulence

DESCRIPTION (provided by applicant): Enterohemorrhagic E. coli (EHEC) O157:H7 is recognized as an important emerging pathogen responsible for producing hemorrhagic colitis and the hemolytic uremic syndrome (HUS) in humans. EHEC O157:H7 strains elaborate a potent Shiga toxin, which has been associated with the pathogenesis of HUS. No pili have yet been reproducibly identified in O157:H7 strains and therefore, it is still an enigma as to whether pili play a role in colonization of the intestine of their natural bovine or accidental human hosts. We have recently identified a novel pilus produced by EHEC strain EDL933 and other O157:H7 strains. These pili, herein called hemorrhagic coli pili 1 (Hcp1), belong to the virulence-associated type IV pili family. Further, purified Hcp1 showed agglutination of rabbit erythrocytes and bound to fibronectin and laminin suggesting an adhesive role in binding to human proteins. An isogenic Hcp1-deficient mutant showed considerably low levels of adherence to cultured cells. The pilin monomer is encoded by the chromosomal prepilin peptidase-dependent ppdD gene, which is adjacent to the type IV-like piliation genes hofBC. Based on our preliminary data, we hypothesize that Hcp1 is a key virulence factor that contributes to the adhesive properties of EHEC. Overall, the objective of this proposal is to advance knowledge of EHEC pathogenesis by elucidating the mechanism(s) of adherence of EHEC O157:H7 to human epithelial cells in culture. Several multidisciplinary approaches involving molecular biology, cell biology, ultrastructural analysis by high power electron microscopy, and biochemical and antigenic analysis will be carried out to extend our current knowledge on the interaction of EHEC O157:H7 with host target cells. The outcome of this proposal will provide important implications for detection of E. coli O157:H7 in food sources and reservoirs and importantly for prevention and control of EHEC infections in humans. The central focus of this proposal lies in structure-function studies of Hcp produced by EHEC. Thus, the following specific aims are proposed: 1) To define the genes required for Hcp1 biogenesis; 2) To define the role of Hcp1; 3) To analyze expression of ppdD.

描述（由申请人提供）：肠出血性大肠杆菌（EHEC）O157:H7被认为是导致人类出血性结肠炎和溶血性尿毒症综合征（HUS）的重要新兴病原体。 EHEC O157:H7 菌株产生一种强效志贺毒素，该毒素与 HUS 的发病机制有关。在 O157:H7 菌株中尚未可重复地鉴定出菌毛，因此，菌毛是否在其天然牛宿主或偶然人类宿主的肠道定植中发挥作用仍然是一个谜。我们最近鉴定了一种由 EHEC 菌株 EDL933 和其他 O157:H7 菌株产生的新型菌毛。这些菌毛，本文称为出血性大肠杆菌菌毛 1 (Hcp1)，属于毒力相关的 IV 型菌毛家族。此外，纯化的 Hcp1 显示出兔红细胞的凝集并与纤连蛋白和层粘连蛋白结合，表明在与人类蛋白质的结合中具有粘附作用。等基因 Hcp1 缺陷突变体对培养细胞的粘附水平相当低。菌毛蛋白单体由染色体前菌毛蛋白肽酶依赖性 ppdD 基因编码，该基因与 IV 型绒毛基因 hofBC 相邻。根据我们的初步数据，我们假设 Hcp1 是影响 EHEC 粘附特性的关键毒力因子。总体而言，该提案的目的是通过阐明 EHEC O157:H7 与培养物中的人上皮细胞的粘附机制来增进对 EHEC 发病机制的了解。将采用多种多学科方法，包括分子生物学、细胞生物学、高功率电子显微镜超微结构分析以及生化和抗原分析，以扩展我们目前关于 EHEC O157:H7 与宿主靶细胞相互作用的知识。该提案的结果将为食物源和储存库中大肠杆菌 O157:H7 的检测以及人类 EHEC 感染的预防和控制提供重要意义。该提案的重点在于 EHEC 产生的 Hcp 的结构功能研究。因此，提出以下具体目标：1）定义Hcp1生物发生所需的基因； 2）定义Hcp1的作用； 3)分析ppdD的表达。