Mechanisms of Clostridium difficile spore germination

 描述（由申请人提供）：艰难梭菌是医院和长期医疗保健机构中腹泻相关性腹泻的主要原因。除了病人的费用，治疗相关的费用C。据估计，美国医疗保健系统的艰难感染费用为32亿美元。虽然C.尽管艰难梭菌在美国的感染率正在上升，但令人惊讶的是，对艰难梭菌的机制知之甚少。难治性发病机制C.艰难梭菌被认为是以休眠孢子的形式被宿主获得的。为了引起疾病，孢子必须在胃肠道中对触发萌发的信号做出反应，从而允许作为营养细菌生长，毒素产生和随后的孢子形成，然后排泄到环境中。我们已经证明，牛磺胆酸，一种通常在胃肠道中发现的胆汁酸，和甘氨酸是C。艰难孢子另一种胆汁酸，鹅去氧胆酸，抑制牛磺胆酸介导的发芽，对C。艰难的营养生长。我们最近确定了胆汁酸在C.艰难梭菌孢子，从而鉴定第一个C.艰难梭菌孢子萌发受体。我们的长期目标是了解C.并利用这些知识来合理地设计C.艰难感染在此应用中，我们提出：（1）确定如何C。艰难梭菌孢子萌发受体与胆汁酸的相互作用;（2）确定结合伴侣和萌发受体在C.艰难梭菌孢子;（3）确定CspC传递胆汁酸信号以启动孢子萌发;以及（4）鉴定其他C.艰难萌发受体。成功完成本文概述的实验将扩展我们对C. difficile germination，为C.艰难梭菌孢子形成和孢子萌发，并导致在其他孢子形成细菌中新发现的萌发受体的同源物的鉴定（打开其他研究途径）。

 DESCRIPTION (provided by applicant): Clostridium difficile is the leading cause of antibiotic-associated diarrhea in the hospital and long term health care settings. In addition to the patient toll, the treatment-associated costs of C. difficile infections to the United States healthcare system have been estimated at $3.2 billion. Although the rate of C. difficile infection in the United States is rising, surprisingly little is known about the mechanisms of C. difficile pathogenesis. C. difficile is believed to be acquired by the host in the form of a dormant spore. To cause disease, the spore must respond in the gastrointestinal tract to signals that trigger germination, thereby allowing growth as a vegetative bacterium, toxin production and subsequent spore formation before excretion into the environment. We have shown that taurocholic acid, a bile acid normally found in the GI tract, and glycine are co-germinants for C. difficile spores. Another bile acid, chenodeoxycholic acid, inhibits taurocholic acid-mediated germination and is toxic for C. difficile vegetative growth. We recently identified the molecular target of bile acids on the C. difficile spore thus identifying the first C. difficile spore germinnt receptor. Our long-term goal is to understand the molecular mechanisms of C. difficile germination and use that knowledge to rationally design inhibitors of C. difficile infection. In ths application, we propose to: (1) identify how the C. difficile spore germinant receptor interacts with bile acids; (2) identify binding partners and the ultrastructural location of the germinant receptor in the C. difficile spore; (3) determine who CspC transmits the bile acid signal to initiae spore germination; and (4) identify other C. difficile germinant receptors. Successful completion of the experiments outlined herein will extend our understanding of the mechanisms of C. difficile germination, open new avenues in the study of C. difficile spore formation and spore germination and lead to the identification of homologs of the newly discovered germinant receptors in other spore-forming bacteria (opening other avenues of investigation).