Novel YcbQ Pili of Enterohemorrhagic E. coli O157:H7

肠出血性大肠杆菌O157:H7的新型YcbQ菌毛

• 批准号: 6862183
• 负责人: JORGE A GIRON
• 金额: $ 13.13万
• 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: 2004-09-15 至 2008-02-28
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6862183
• 关键词: Escherichia coli 0157:H7; adhesin; bacteria infection mechanism; bacterial genetics; bioterrorism /chemical warfare; cell adhesion; clinical research; electron microscopy; epithelium; gene expression; genetic transcription; hemolytic anemia; hemorrhagic disorders; host organism interaction; microorganism growth; peptidases; pilin; protein biosynthesis; protein purification; protein structure function; renal failure; shiga toxin; tissue /cell culture; virulence; western blottings

DESCRIPTION (provided by applicant): Enterohemorrhagic E. coil (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 and purified a novel pilus structure produced by EHEC strain EDL933 and other O157:H7 strains. These pili are composed of an 18- kDa pilin subunit and its amino terminus shows identity to the predicted product of the ycbQ gene contained in the EDL933 chromosome. Sequence comparison analysis revealed that these pili, herein called YcbQ, belong to the virulence-associated pili family composed of F17, K99, and G pili found in several animal and human pathogenic E. coli strains, and CupA pili of Pseudomonas aeruginosa. Four genes (ycbQ, ycbR, ycbS, ycbT) with homology to F17 family piliation genes were identified by sequence homology in the genome of EDL933, being ycbQ the structural gene. 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 carded 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 diagnosis of EHEC disease and detection of O157:H7 in food sources and reservoirs. The information obtained will be important for prevention and control strategies of EHEC infections. The central focus of this proposal lies in the following specific aims: 1) To define the genes required for YcbQ pili biogenesis; 2) Define the role of YcbQ pili; and 3) Study transcriptional expression of ycb genes.

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。我们最近鉴定并纯化了肠出血性大肠杆菌 EDL933 菌株和其他 O157:H7 菌株产生的新型菌毛结构。这些菌毛由 18-kDa 菌毛蛋白亚基组成，其氨基末端与 EDL933 染色体中包含的 ycbQ 基因的预测产物相同。序列比较分析表明，这些菌毛（本文称为 YcbQ）属于毒力相关菌毛家族，由在几种动物和人类致病性大肠杆菌菌株中发现的 F17、K99 和 G 菌毛以及铜绿假单胞菌的 CupA 菌毛组成。通过序列同源性，在EDL933基因组中鉴定出与F17家族毛发基因同源的4个基因（ycbQ、ycbR、ycbS、ycbT），其中ycbQ为结构基因。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。将采用一些涉及分子生物学、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的多学科方法，以扩展我们目前对 EHEC O157:H7 与宿主靶细胞相互作用的知识。该提案的结果将为肠出血性大肠杆菌疾病的诊断以及食物源和储存库中 O157:H7 的检测提供重要意义。获得的信息对于肠出血性大肠杆菌感染的预防和控制策略非常重要。该提案的中心重点在于以下具体目标：1）定义YcbQ菌毛生物发生所需的基因； 2）定义YcbQ pili的作用； 3)研究ycb基因的转录表达。