INVESTIGATION OF TWO VIRULENCE MECHANISMS OF PSEUDOMONAS AERUGINOSA

这个子项目是许多利用资源的研究子项目之一 由NIH/NCRR资助的中心拨款提供。子项目的主要支持 而子项目的主要调查员可能是由其他来源提供的， 包括其它NIH来源。 列出的子项目总成本可能 代表子项目使用的中心基础设施的估计数量， 而不是由NCRR赠款提供给子项目或子项目工作人员的直接资金。 本提案的目的是解决两个未知的细菌铜绿假单胞菌的毒力。 第一个目的是确定除了mucA突变之外，引起囊性纤维化患者的临床分离株粘液样转化的机制。 第二个目的是确定伴侣SpcU在III型外毒素ExoU分泌中所起的作用是否是保持ExoU可溶和稳定。 ExoU是铜绿假单胞菌的强效细胞毒素。 这项研究的长期目标是增加我们对细菌致病机制的理解。 待检验的假设是：1）MucA上游因子或RpoN途径中的缺陷介导mucA+临床分离株中的类粘蛋白转化，以及（2）铜绿假单胞菌伴侣SpcU通过结合其C-末端膜定位结构域和其N-末端伴侣结合结构域来保持毒素ExoU可溶性和分泌能力。 这些假设将通过追求两个特定目标进行测试：1）鉴定介导mucA+菌株中的类粘蛋白转化的机制;和2）检查假单胞菌分子伴侣在促进外毒素的溶解度、稳定性和分泌中的作用。 对于目标1，我们将对粘液样mucA+临床分离株进行遗传分析，以确定最近鉴定的调节因子（AlgW和RpoN）是否在这些菌株中被激活。 对于目标2，我们将检查ExoU的C-末端膜定位结构域和N-末端伴侣结合结构域的突变对其与SpcU的相互作用以及对其溶解性、稳定性和分泌能力的影响。该提议是创新的，因为它将利用外毒素ExoU的独特性质以及我们对粘液转化的其他调节剂的发现和表征。 该研究对于进一步理解铜绿假单胞菌和其他致病菌的两种毒力机制具有重要意义。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. The objectives of this proposal are to address two unknowns about the virulence of the bacterium Pseudomonas aeruginosa. The first objective is to identify the mechanism(s) causing mucoid conversion of clinical isolates from cystic fibrosis patients besides mutations in mucA. The second objective is to determine if the role that the chaperone SpcU plays in the secretion of the Type III exotoxin ExoU is to keep ExoU soluble and stable. ExoU is a potent cytotoxin of P. aeruginosa. The long term goal of this research is to increase our understanding of the mechanisms used by bacteria to cause disease. The hypotheses to be tested are: 1) that defects in factors upstream of MucA or in the RpoN pathway mediate mucoid conversion in mucA+ clinical isolates and (2) that the P. aeruginosa chaperone SpcU acts to keep the toxin ExoU soluble and secretion competent by binding to both its C-terminal membrane localization domain and its N-terminal chaperone binding domain. These hypotheses will be tested by pursuing two specific aims: 1) Identify mechanisms mediating mucoid conversion in mucA+ strains; and 2) Examine the role of Pseudomonas chaperones in promoting the solubility, stability and secretion of exotoxins. For aim 1, we will perform genetic analyses of mucoid mucA+ clinical isolates to determine if recently identified regulators (AlgW and RpoN) are activated in these strains. For aim 2, we will examine the effect of mutations of the C-terminal membrane localization domain and N-terminal chaperone binding domain of ExoU on its interaction with SpcU, and on its solubility, stability and ability to be secreted. This proposal is innovative because it will take advantage of unique properties of the exotoxin ExoU and of our discovery and characterization of additional regulators of mucoid conversion. The proposed research is significant because it is expected to advance our understanding of two virulence mechanism used by P. aeruginosa and other pathogenic bacteria.