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Urea-dependent virulence in uropathogenic bacteria

尿路致病菌的尿素依赖性毒力

基本信息

批准号：
6788698
负责人：
CARLEEN M. COLLINS
金额：
$ 32万
依托单位：
UNIVERSITY OF WASHINGTON
依托单位国家：
美国
项目类别：
财政年份：
2001
资助国家：
美国
起止时间：
2001-09-21 至 2006-06-30
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/6788698
关键词：
DNA Enterobacteriaceae Proteus X ray crystallography biological signal transduction chemical binding conformation structural biology transcription factor urea urease virulence

项目摘要

DESCRIPTION(provided by applicant: Urease, which catalyzes the hydrolysis of urea to ammonia and carbonic acid is produced by diverse bacterial species including various aerobes, facultative anaerobes and obligate anaerohes Both Gram-negative and Gram-positive organisms are urease producers, as are species of mycobacteria and ureaplasma. Urease plays a significant role in virulence when expressed by urinary tract, oral, and gastroduodenal pathogens. Providencia stuartii and Proteus inirabilis, the two most common ureolytic uropathogens, express urcase only in the presence of urea. This urea-dependent expression is mediated by UreR, a transcriptional activator belonging to the AraCfamily of regulators. Evidence suggests that urea interacts directly with UreR, and thus is the effector molecule for this activator. Urea is Found at concentrations up to 500 mM in the urinary tract, a concentration that is at least 50 fold higher than that observed at other sites in the body. Thus for these uropathogens, urea is a signal molecule, and UreR is acting as a signal receptor, alerting the organism that it is in the urinary tract. UreR bound to urea is active as an transcriptional activator and has a high affinity for DNA. UreR not bound to urea is not active and has a low affinity for the I)NA binding site. Studies in this proposal are to examine the urea-UreR interaction and to determine the conformational changes associated with urea binding that result in active UreR. Two models are proposed, one in which UrcR forms a dimer, and the other in which UreR is active as a monomer. Studies are proposed to prove one of these models. The crucial urca-UreR interaction is examined in Aim #1, and the urea-UreR-DNA interaction in Aim #2. Aim #3 is to determine the X-ray structure of UreR, UreR bound to urea, and UreR bound to urea and the DNA binding site. Structures of mutant forms of UreR will also be generated. This work will elucidate the molecular mechanisms of this important regulator of a urovirulence, as well as extend our knowledge on the AraC-fainily of transcriptional activators.

描述（由申请人提供：尿素酶，催化水解尿素转化为氨和碳酸是由不同的细菌物种产生的包括各种需氧菌、兼性厌氧菌和专性厌氧菌。革兰氏阴性菌和革兰氏阳性菌都是脲酶生产者，分枝杆菌和脲原体脲酶在致病性中起重要作用当由泌尿道、口腔和胃十二指肠病原体表达时。斯氏普罗威登斯菌和变形杆菌，两种最常见的尿素分解菌尿病原体，表达urcase仅在尿素的存在下。这种依赖尿素的表达是由UreR介导的，UreR是一种转录激活因子，属于 AraC系列调节器。有证据表明，尿素直接与 UreR，因此是该激活剂的效应分子。尿素在在泌尿道中的浓度高达500 mM，比在身体其他部位观察到的高至少50倍。因此对于在这些尿路病原体中，尿素是一种信号分子，UreR是一种信号分子，受体，提醒有机体，它是在泌尿道。UreR结合尿素作为转录激活剂是有活性的，并且对DNA具有高亲和力。不与尿素结合的UreR没有活性，并且对I）NA具有低亲和力结合位点本研究旨在研究尿素-尿素受体相互作用并确定与尿素结合相关的构象变化，导致UreR活性。提出了两种模型，一种是UrcR形成一个二聚体，和另一个其中UreR作为单体是活性的。建议进行研究来证明其中一个模型关键的urca-UreR相互作用在目标#1中的尿素-UreR-DNA相互作用，以及目标#2中的尿素-UreR-DNA相互作用。目标#3是确定 UreR、与尿素结合的UreR以及与尿素结合的UreR和DNA的X射线结构结合位点还将产生UreR的突变形式的结构。这这项工作将阐明这一重要调节因子的分子机制，尿毒力，以及扩大我们的知识对阿糖胞苷-模糊的转录激活因子。