Contribution of novel frimbriae to Proteus mirabilis virulence

描述（由申请人提供）：尿路感染是美国最常见的细菌感染之一，奇异变形杆菌是肠杆菌科的一员，是复杂尿路患者感染的主要原因。虽然在奇异假单胞菌中已经确定了几个毒力因子，但最近完成的该基因组测序有可能大大增加我们对奇异假单胞菌发病机制的理解。菌毛，从细菌细胞表面延伸的结构，通常参与定植和疾病进展。值得注意的是，我们在P. mirabilis基因组中注释了17个潜在的伴侣-引导菌毛，其中只有5个是之前发现的。本课题的第一个具体目标是研究这些菌毛的一般表达特征，并选择一种新的菌毛进行进一步的详细研究。RT-PCR，微阵列分析在实验性尿路感染小鼠模型中表达的基因，以及表面表达蛋白的质谱分析将用于研究与疾病过程相关的功能纤维。敲除和过表达研究将被用来阐明毛的功能，包括细胞培养或细胞外基质成分的粘附性和小鼠尿路的实验感染。在17个潜在的毛状操纵子中，有10个含有一个编码转录调控因子的基因。通过与mrp毛缘操纵子mrpJ的同源性鉴定，这些调节因子中的大多数抑制鞭毛运动。初步结果表明，mrpJ类似物也可能调节其他功能，包括其他菌毛的表达。本提案的第二个特定目标侧重于与特定目标1中概述的膜相关的mrpJ平行体。mrpJ序列的过表达和敲除菌株将与已知菌毛的微阵列研究和分析相结合。从这些研究中获得的数据不仅将增加我们对P. mirabilis发病机制的了解，并可能导致针对uti的新措施，而且还将与粘膜表面的其他病原体相关。细菌病原体奇异变形杆菌可导致泌尿道衰弱性疾病，包括膀胱和肾结石的形成。我们最近完成的P. mirabilis基因组序列导致许多以前未知的，潜在的毒力因素的发现。这个项目的目标是研究这些毒力因素之一是如何促进疾病过程的。

DESCRIPTION (provided by applicant): Urinary tract infections are one of the most common bacterial infections in the U.S. Proteus mirabilis, a member of the Enterobacteriaceae, is a major cause of infection in individuals with complicated urinary tracts. Although several virulence factors have been identified in P. mirabilis, the recent completion of the sequencing of this genome has the potential to greatly increase our understanding of P. mirabilis pathogenesis. Fimbriae, structures that extend from the bacterial cell surface, are often involved in colonization and disease progression. Remarkably, 17 potential chaperone-usher fimbriae were annotated by us in the P. mirabilis genome, only five of which had been previously identified. The first Specific Aim of this proposal is to study general expression characteristics of these fimbriae, and to choose one of the novel fimbriae to study in further detail. RT-PCR, microarray analysis of genes expressed during experimental urinary tract infection in a mouse model, and mass spectrometry of surface-expressed proteins will be used to hone in on a functional fimbria relevant to the disease process. Knockout and overexpression studies will be employed to elucidate the function of the fimbria using assays including adherence to cell culture or extracellular matrix components and experimental infections of the murine urinary tract. Ten of the 17 potential fimbrial operons in P. mirabilis contain a gene encoding a transcriptional regulator. The majority of these regulators, identified by their homology to mrpJ in the mrp fimbrial operon, inhibit flagellar motility. Preliminary results suggest that mrpJ paralogs likely also regulate other functions, including expression of other fimbriae. The second Specific Aim of this proposal focuses on the mrpJ paralog associated with the fimbria outlined in Specific Aim 1. Overexpression and knockout strains of the mrpJ paralog will be coupled with microarray studies and analysis of known fimbriae. Data gained from these studies will not only increase our knowledge about P. mirabilis pathogenesis and potentially lead to new measures against UTIs, but also will be relevant to other pathogens of mucosal surfaces. The bacterial pathogen Proteus mirabilis can cause debilitating disease in the urinary tract, including the formation of bladder and kidney stones. Our recent completion of the P. mirabilis genome sequence led to the discovery of many previously unknown, potential virulence factors. The goal of this project is to study how one of these virulence factors might contribute to the disease process.