StcE, an E.coli O157:H7 Protease Specific for C1-Inh

StcE，一种针对 C1-Inh 的大肠杆菌 O157:H7 蛋白酶

• 批准号: 7009264
• 负责人: Rodney A. Welch
• 金额: $ 32.84万
• 依托单位: UNIVERSITY OF WISCONSIN-MADISON
• 依托单位国家: 美国
• 财政年份: 2003
• 资助国家: 美国
• 起止时间: 2003-01-16 至 2007-12-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7009264
• 关键词: StcE; E.coli; O157; H7; Protease

DESCRIPTION (Provided by applicant): Enterohemorrhagic Escherichia coli (EHEC), principally serotype O157:H7, cause an estimated 20,000 cases of diarrheal disease in the United States per year. 2-6 percent of the infected individuals, mostly young children progress to a severe renal disease, hemolytic uremic syndrome (HUS). The EHEC pathogenic factors that lead to bloody colitis and HUS are poorly understood, but knowledge of some mechanisms has recently emerged. Intimin-mediated adherence and type III effectors are encoded by a chromosomal locus termed LEE. The phage-encoded Shiga toxins (Stxs) are responsible for significant aspects of EHEC disease. EHEC strains commonly possess large plasmids, the prototype being pO157. We have identified a new pO157 gene, stcE, which encodes an extracellular zinc-metalloendoprotease (ZMP) that specifically cleaves the critical anti-inflammatory regulator C l-esterase inhibitor (C 1-Inh). C 1-Inh is a serine protease inhibitor (serpin) that provides the principal inhibition of the proteolytic cascades involved in classic and mannan-binding ligand complement activation, contact activation and intrinsic coagulation. C l-Inh inhibits diverse proteases: Clr and Cls, MASP-1, MASP-2, kallikrein, FXIIa, FXIa, and plasmin. Deficiencies in Cl-Inh cause profound clinical syndromes. The best known is hereditary angioedema (HAE), a genetic deficiency in Cl-Inh, which is characterized by transient, recurrent attacks of intestinal cramps, vomiting, diarrhea and life-threatening episodes of tracheal swelling. Fluorescenated StcE binds to cultured macrophages, B- and T-cells. Thus, StcE is an example of a growing class of ZMPs such as tetanus, botulinum and anthrax lethal factor toxins. These ZMPs, in contrast to the homologous Pseudomonas and Vibrio ZMPs, have specific, non-extracellular matrix protein targets. We will test the hypothesis that StcE degrades soluble or cell-associated Cl-Inh, and this results in poorly regulated serine protease cascades involving complement activation, contact activation and coagulation. This dysregulation would then contribute to local inflammation, tissue damage and edema. The elucidation of StcE structure and function(s) may result in new targets for chemotherapeutic or immune prevention or treatment of EHEC infections, which now are best managed only by supportive therapy.

描述(由申请人提供)：肠出血性大肠杆菌(EHEC)，主要是O157：H7血清型，每年在美国导致大约20,000例腹泻疾病。2-6%的感染者，主要是幼儿，进展为严重的肾脏疾病，溶血性尿毒症综合征(HUS)。导致出血性结肠炎和HUS的EHEC致病因素尚不清楚，但最近出现了一些机制的知识。内膜蛋白介导的黏附和III型效应器由一个名为Lee的染色体位点编码。噬菌体编码的志贺毒素(Stxs)是EHEC疾病的重要组成部分。EHEC菌株通常具有大的质粒，原型是pO157。我们发现了一个新的pO157基因stcE，它编码一种胞外锌金属内切酶(ZMP)，该酶能特异性地裂解关键的抗炎调节因子C L-酯酶抑制物(C1INH)。C1-inh是一种丝氨酸蛋白酶抑制剂(Serpin)，它主要抑制蛋白水解级联反应，参与经典的和甘露聚糖结合的补体激活、接触激活和内凝血。C L-Inh抑制多种蛋白水解酶：CLR和CLS、Masp-1、Masp-2、激肽释放酶、FXIIa、FXIa和纤溶酶。氯-异烟肼缺乏会导致严重的临床症状。最著名的是遗传性血管水肿(HAE)，这是一种氯-异烟肼的遗传缺陷，其特征是一过性、反复发作的肠道痉挛、呕吐、腹泻和危及生命的气管肿胀发作。荧光标记的StcE与培养的巨噬细胞、B细胞和T细胞结合。因此，StcE是破伤风、肉毒杆菌和炭疽致命因子毒素等越来越多的ZMP的一个例子。这些ZMP与假单胞菌和弧菌ZMP不同，它们具有特定的、非细胞外基质蛋白靶标。我们将检验StcE降解可溶性或细胞相关的Cl-Inh的假设，这会导致调节不佳的丝氨酸蛋白酶级联，涉及补体激活、接触激活和凝血。这种失调会导致局部炎症、组织损伤和水肿。对StcE结构和功能的阐明(S)可能会为EHEC感染的化疗或免疫预防或治疗带来新的靶点，目前只有支持性治疗才能最好地管理这些感染。