Role of PrrF and PrrH regulation in Pseudomonas aeruginosa pathogenesis

项目摘要 铜绿假单胞菌是一种多功能的细菌病原体，可引起危及生命的急性和慢性 不同患者群体中的感染。使治疗复杂化的是铜绿假单胞菌抵抗细菌的能力。 大多数抗菌治疗。因此，关键是要确定毒力特性，可以针对 新疗法的发展。一些研究表明铁稳态对P。 铜绿假单胞菌致病机制我们实验室最近的工作表明，铜绿假单胞菌prrF染色体位点， 其编码铁响应性PrrF 1和PrrF 2小调节RNA（sRNA），是急性肺损伤所必需的。 感染小鼠。PrrF 1和PrrF 2 sRNA通过抑制以下蛋白的表达来促进铁稳态： 铁的利用途径，当这种营养是有限的。这种“铁节约反应”进一步影响了各种 毒力特性，包括群体感应和生物膜形成。prrF基因座产生一种独特的sRNA （PrrH），由血红素调节，血红素是人体内丰富的铁来源，因此将铁和血红素连接起来 铜绿假单胞菌的稳态途径。虽然我们的研究已经确定了这个基因座对 P.铜绿假单胞菌的生理学和毒力，从这个转录的单个sRNAs的机制， 基因座介导的基因表达和发病机制仍不清楚。根据我们的初步和公布的 研究中，我们假设PrrF和PrrH sRNA在调节P. 铜绿假单胞菌铁稳态和毒力。我们将通过以下方式检验我们的假设：1）鉴定PrrF靶mRNA 2）确定血红素的遗传基础 通过PrrH sRNA调节表达; 3）确定PrrF和PrrH调节的机制 基因表达。这些研究将明确prrF转录的sRNA的具体机制， 介导铁稳态和铜绿假单胞菌的毒力。

PROJECT SUMMARY Pseudomonas aeruginosa is a versatile bacterial pathogen that causes life-threatening acute and chronic infections in diverse patient populations. Complicating treatment is the ability of P. aeruginosa to resist the majority of antimicrobial therapies. It is therefore critical to identify virulence properties that can be targeted for the development of novel therapeutics. Several studies demonstrate the importance of iron homeostasis for P. aeruginosa pathogenesis. Recent work from our lab shows that the P. aeruginosa prrF chromosomal locus, which encodes the iron-responsive PrrF1 and PrrF2 small regulatory RNAs (sRNAs), is required for acute lung infection in mice. The PrrF1 and PrrF2 sRNAs contribute to iron homeostasis by repressing the expression of iron-utilizing pathways when this nutrient is limiting. This “iron sparing response” further impacts diverse virulence properties, including quorum sensing and biofilm formation. The prrF locus produces a distinct sRNA (PrrH) that is regulated by heme, an abundant source of iron in the human body, thus linking iron and heme homeostasis pathways of P. aeruginosa. While our studies have established the broad impact of this locus on P. aeruginosa physiology and virulence, the mechanisms by which the individual sRNAs transcribed from this locus mediate gene expression and pathogenesis remain unknown. Based on our preliminary and published studies, we hypothesize that the PrrF and PrrH sRNAs play critical yet distinct roles in regulating P. aeruginosa iron homeostasis and virulence. We will test our hypothesis by 1) identifying PrrF target mRNAs responsible for virulence attenuation of the ΔprrF1,2 mutant; 2) determining the genetic basis of heme regulated expression via the PrrH sRNA; and 3) defining the mechanisms by which PrrF and PrrH regulate gene expression. These studies will define the specific mechanisms by which the prrF-transcribed sRNAs mediate iron homeostasis and virulence of P. aeruginosa.