Regulation of EHEC virulence genes by QseA and small RNA molecules

描述(申请人提供)：肠出血性大肠杆菌(EHEC)O157：H7在世界各地引起血性腹泻和溶血性尿毒症系统(HUS)。EHEC的感染剂量非常低，因此很难在流行病学上进行控制。EHEC在大肠内定植，造成附着和消失(AE)损害，并产生导致HUS主要症状的志贺毒素。每年，仅在美国，EHEC就导致7万多人患病，2000人住院，7万人死亡。EHEC感觉正常的胃肠道菌群产生的细菌自身诱导物(AI-3)，以及宿主产生的肾上腺素和去甲肾上腺素来激活其毒力基因的表达。毒力基因的额外调节通过转录因子QseA和小RNA分子(SRNAs)进行。然而，有关QseA和sRNA基因调控的许多方面仍然知之甚少，这两个基因对毒力至关重要。这一应用代表了对EHEC中负责毒力基因调控的QseA和sRNAs功能的全面探索。其目的是(1)确定QseA激活和抑制靶基因的机制，(2)表征QseA在EHEC毒力基因调控中的作用，(3)阐明小RNA(SRNA)分子在EHEC转录后基因调控中的作用。所提出的实验方法将更好地理解EHEC激活其毒力基因的机制，并可能揭示EHEC发病机制的潜在新方面。这些数据可能最终导致针对EHEC感染的独特治疗策略的开发。

DESCRIPTION (provided by applicant): Enterohemorrhagic E. coli (EHEC) O157:H7 causes bloody diarrhea and hemolytic uremic system (HUS) throughout the world. EHEC has a very low infectious dose, making it difficult to control epidemiologically. EHEC colonizes the large intestine where it causes attaching and effacing (AE) lesions and also produces Shiga toxins that are responsible for the major symptoms of HUS. Each year, EHEC causes more than 70,000 illnesses, 2000 hospitalizations, and 70,000 deaths in the United States alone. EHEC senses a bacterial autoinducer (AI-3) produced by the normal gastrointestinal flora, as well as the hormones epinephrine and norepinephrine produced by the host to activate expression of its virulence genes. Additional regulation of virulence genes occurs through the transcription factor QseA and small RNA molecules (sRNAs). However, many aspects concerning QseA and sRNA gene regulation, which are critical for virulence, remain poorly understood. This application represents a comprehensive effort to explore the functions of QseA and of sRNAs responsible for virulence gene regulation in EHEC. The Specific Aims are (1) To determine the mechanism of QseA activation and repression of target genes, (2) To characterize the role of QseA in EHEC virulence gene regulation, and (3) To elucidate the roles of small RNA (sRNA) molecules in post-transcriptional gene regulation in EHEC. The proposed experimental approaches will achieve a better understanding of the mechanisms employed by EHEC to activate its virulence genes and may reveal potentially novel aspects of EHEC pathogenesis. These data may ultimately lead to the development of unique treatment strategies for EHEC infection.