Campylobacter jejuni DNA methylation and gene regulation

描述（由申请人提供）：空肠弯曲杆菌是美国国立卫生研究院分类的B类生物恐怖制剂。它是美国细菌性肠胃炎的主要原因，是散发疾病以及食源性和水传播疾病爆发的原因。美国每年至少有240万例空肠梭菌胃肠炎，其发病率超过沙门氏菌和志贺氏菌的总和(1)。空肠梭菌感染也是发展为格林-巴尔综合征的最常见的前事件，格林-巴尔综合征是一种急性运动麻痹，显然是由针对空肠梭菌表面抗原的自身免疫反应引起的。尽管弯曲杆菌病的高患病率和超过20年的研究，由空肠梭菌引起疾病的机制仍然不清楚。几个空肠梭菌的毒力因素已经确定，但其调控机制在很大程度上是未知的。

DESCRIPTION (provided by applicant): Campylobacter jejuni is a Category B Bioterrorism Agent as classified by the NIH. It is the leading cause of bacterial gastroenteritis in the United States, and is responsible for sporadic disease as well as food-borne and water-borne outbreaks. There are at least 2.4 million cases of C. jejuni gastroenteritis in the U.S. annually, with an incidence exceeding that of Salmonella and Shigella combined (1). C. jejuni infection is also the most common antecedent event to development of Guillain-Barr Syndrome, an acute motor paralysis apparently resulting from an autoimmune response directed at C. jejuni surface antigens. Despite the high prevalence of Campylobacter disease and more than 20 years of study, the mechanisms by which C. jejuni causes disease remain obscure. Several C. jejuni virulence factors have been identified, yet their regulatory mechanisms are largely unknown. Recent evidence implicates DNA methylation as an important signal controlling virulence gene expression in Salmonella and other bacteria. In light of this, our studies on the predicted C. jejuni DNA methylase Cj1461 showed that cj1461 was induced at 37C, the internal temperature of humans, consistent with a role in pathogenic growth adaptation. Further experiments revealed that mutation of cj1461 resulted in the dramatically altered expression of ca. 50-60 proteins, including known virulence factors and additional predicted regulatory proteins such as the orphan response regulator Cj0355. Consequently, Cj1461 appears to be involved in a complex regulatory circuit controlling expression of numerous C. jejuni genes; growth temperature is one of the signals. We now propose further study of gene regulation in C. jejuni, focusing on those proteins that are regulated by the predicted DNA methylase Cj1461 and the orphan response regulator Cj0355. We will use a combination of microarray, proteomics, and biochemical approaches to achieve the goals outlined in these three specific aims: Specific Aim 1. Determine the functional properties of Cj1461 and Cj0355 responsible for modulating virulence gene expression. Specific Aim 2. Identify the downstream targets of Cj1461 and Cj0355 to define their combinatorial impact on gene regulation. Specific Aim 3. Elucidate the upstream factors and signals controlling Cj1461 and Cj0355 expression to reveal the entire regulatory circuit.