Control of Pseudomonas aeruginosa Quorum Sensing and Alginate

描述（由申请方提供）：铜绿假单胞菌是一种普遍存在的机会致病菌，主要感染免疫系统受损的个体，包括移植患者、严重烧伤患者和囊性纤维化（CF）患者。在CF的背景下，铜绿假单胞菌建立了一种慢性病症，其发病率和死亡率由肺损伤引起。由于不可思议的抗生素耐药性，感染假单胞菌的CF患者通常患有慢性感染，治疗选择有限。因此，为了提高治疗效果，需要对这种生物体利用的致病机制进行基本了解，以寻找可能的治疗靶点。虽然大多数以前的研究都集中在殖民和感染的初始阶段，我们提出了一种新的方法来寻找治疗。越来越多的证据表明，生物膜生长模式最有可能参与铜绿假单胞菌的发病机制。铜绿假单胞菌在这种生长条件下产生许多毒力因子，包括藻酸盐、鼠李糖脂、IV型皮利和氰化物。其他人和我们已经发现，反应调节因子AlgR控制所有这些毒力因子。我们发现AlgR是生物膜形成所需的，并且它抑制生物膜中的Rhl群体感应系统。我们最近创建了一个组成型活性的algR等位基因algRD 54 E。染色体上携带algRD 54 E的PAO 1在生物膜形成中有缺陷，并且不产生绿脓菌素。我们的数据显示了AlgR的两个新作用：（i）AlgR在组成性“开启”时能够抑制和激活基因;（ii）AlgR控制铜绿假单胞菌的Rhl群体感应系统。拟议的研究是创新的，因为我们正在研究群体感应在粘液P.A.中的作用。拟议的研究也是创新的，因为我们正在确定一种转录调节因子的机制，这种转录调节因子调节五种不同的毒力因子，并且当它被磷酸化或未磷酸化时可以激活转录。待检验的假设是：AlgR控制粘液P.a.中的Rhl群体感应系统，从而使生物体在慢性感染中持续存在。我们将用两个具体目的来检验这一假设：1）我们将在体外P.a. 2）我们将确定AlgR对P. a.毒性。

DESCRIPTION (provided by applicant): Pseudomonas aeruginosa is a ubiquitous, opportunistic pathogen primarily infecting individuals with a compromised immune system, including transplant patients; severe burn patients, and those with cystic fibrosis (CF). In the context of CF, P. aeruginosa establishes a chronic condition whose morbidity and mortality results from lung damage. Due to the uncanny antibiotic resistance, CF patients infected with Pseudomonas often have chronic infections with limited therapeutic options. Therefore, for improved efficacy in treatment, a basic understanding of the pathogenic mechanisms utilized by this organism needs to be examined for possible therapeutic targets. While a majority of previous studies have focused on the initial stages of colonization and infection, we propose a new approach in searching for treatments. Mounting evidence indicates that a biofilm mode of growth is most likely involved in P. aeruginosa pathogenesis. Many virulence factors are produced by P. aeruginosa under this growth condition including alginate, rhamnolipids, type IV pili and cyanide. Others and we have discovered that a response regulator AlgR, controls all of these virulence factors. We discovered that AlgR is required for biofilm formation and that it represses the Rhl quorum sensing system in a biofilm. We have most recently created an algR allele that is constitutively active, algRD54E. PAO1 harboring algRD54E on the chromosome is defective in biofilm formation and does not produce pyocyanin. Our data show two new roles for AlgR: (i) AlgR is able to repress and activate genes when it is constitutively "on" and; (ii) AlgR is controlling the Rhl quorum sensing system of P. aeruginosa. The proposed research is innovative because we are examining the role of quorum sensing in mucoid P.a.. The proposed research is also innovative because we are determining the mechanism for a transcriptional regulator that regulates five different virulence factors and can activate transcription when it is either phosphorylated or unphosphorylated. The hypothesis to be tested is: AlgR controls the Rhl quorum sensing system in mucoid P.a., thus allowing the organism to persist in chronic infections. We will test this hypothesis with two specific aims: 1) We will determine the mechanism of AlgR control on the Rhl QS system in in vitro P.a. biofilm formation and 2) We will determine the mechanism of AlgR control on the Rhl QS system in P.a. virulence.