Role of PrrF and PrrH regulation in Pseudomonas aeruginosa pathogenesis

项目总结 铜绿假单胞菌是一种多种致病菌，可引起危及生命的急性和慢性疾病。 不同患者群体中的感染。复杂的治疗是铜绿假单胞菌抵抗 大多数的抗菌疗法。因此，确定可作为靶标的毒力特性至关重要 新疗法的发展。几项研究证明了铁的动态平衡对P。 铜绿假单胞菌的发病机制。我们实验室最近的研究表明，铜绿假单胞菌prrF染色体上， 它编码铁反应PrrF1和PrrF2小调节RNA(SRNAs)，是急性肺病所必需的 小鼠的感染。PrrF1和PrrF2 sRNAs通过抑制铁蛋白的表达促进铁稳态。 当这种营养有限时，铁的利用途径。这种“省铁的应对措施”进一步影响了 毒力特性，包括群体感应和生物膜形成。PrrF基因座产生一个独特的sRNA (PrrH)受人体内丰富的铁来源--血红素的调节，从而将铁和血红素联系起来 铜绿假单胞菌的动态平衡途径虽然我们的研究已经确定了这个基因座对 铜绿假单胞菌的生理和毒力，个体sRNAs转录的机制 介导基因表达的基因位点和发病机制尚不清楚。基于我们的初步和出版 研究表明，我们推测PrrF和PrrH sRNAs在调节P. 铜绿假单胞菌铁的动态平衡和毒力。我们将通过1)识别PrrF靶向mRNAs来验证我们的假设 负责ΔprrF1，2突变体的毒力减弱；2)确定血红素的遗传基础 通过PrrH SRNA调控表达；以及3)确定PrrF和PrrH调控的机制 基因表达。这些研究将确定PrrF转录的sRNA的具体机制 调节铜绿假单胞菌的铁稳态和毒力。

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.