Recombinase FimX: Role in type 1 pili regulation and

重组酶 FimX：在 1 型菌毛调节和

• 批准号: 7076649
• 负责人: Patrick C. Seed
• 金额: $ 11.42万
• 依托单位: DUKE UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2006
• 资助国家: 美国
• 起止时间: 2006-07-10 至 2009-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7076649
• 关键词: DNA; Escherichia coli; Escherichia coli infections; bacteria infection mechanism; biofilm; biological models; cell adhesion; enzyme activity; gene targeting; genetic susceptibility; host organism interaction; immunoprecipitation; laboratory mouse; nucleic acid sequence; pathologic process; pilus; protein structure function; recombinase; urinary bladder epithelium; urinary tract infection; virulence

DESCRIPTION (provided by applicant): Type 1 pili, the preeminent virulence determinant in Escherichia coli-associated cystitis, promote binding to the bladder surface and facilitate the colonization and invasion of the epithelium. In their intracellular residence, E. coli amass into communal formations with biofilm-like properties termed intracellular bacterial communities (IBC) and then disperse and flux from the infected cell into the lumen of the bladder. Upon fluxing, type 1 pili may again mediate adherence to naive epithelial cells, reinitiating invasion and IBC formation. Because of the central role of type 1 pili in uropathogenesis, understanding the regulation of these fibers is essential for a complete molecular description of the infection and ultimately to identify novel targets for therapeutics. Type 1 pili are regulated by two recombinases, FimB and FimE, that together dynamically modulate the expression of the fibers through phase variation whereby the promoter region is inverted into ON and OFF positions. Preliminary studies have identified FimX, a third site-specific recombinase that, despite the absence of FimB and FimE, produces phase variation and the expression of type 1 pili and supports full virulence. Ablation of FimX and the other two recombinases renders the organism avirulent. We hypothesize that FimX, as regulator of type 1 pili expression, is a central virulence determinant in E. coli urinary tract infections. In Aim 1 of this proposal, we will use a combination of molecular epidemiology, genetics, and animal modeling to characterize the prevalence of fimX and study the in vivo role of FimX as a regulator of type 1 pili in E. coli cystitis. In Aim 2, through the use of genetics and biochemistry, we will study the structure-function relationships of FimX and its target DNA sequences. Given the central role of the Fim recombinases in regulating type 1 pili expression, understanding their functions and constraints may yield novel points for treatment and prevention in urinary tract infections.

描述（由申请人提供）： 1型皮利是大肠杆菌相关性膀胱炎中的主要毒力决定因子，可促进与膀胱表面的结合并促进上皮的定植和侵袭。在细胞内，E.大肠杆菌聚集成具有生物膜样特性的公共结构，称为细胞内细菌群落（IBC），然后从受感染的细胞分散并流入膀胱腔。在流动时，1型皮利可再次介导对幼稚上皮细胞的粘附，重新启动侵袭和IBC形成。由于1型皮利在泌尿系发病机制中的核心作用，了解这些纤维的调节对于完整的感染分子描述和最终确定新的治疗靶点至关重要。1型皮利由两种重组酶FimB和FimE调节，这两种重组酶一起通过相位变化动态地调节纤维的表达，由此启动子区被反转成ON和OFF位置。初步研究已经鉴定了FimX，这是第三种位点特异性重组酶，尽管不存在FimB和FimE，但其产生相位变化和1型皮利的表达，并支持完全毒力。切除FimX和其他两种重组酶使生物体无毒。我们假设FimX作为1型皮利表达的调节因子，是大肠杆菌的一个中心毒力决定因子。大肠杆菌尿路感染。在本提案的目标1中，我们将使用分子流行病学、遗传学和动物模型的组合来表征fimX的流行，并研究FimX作为大肠杆菌中1型皮利调节剂的体内作用。大肠杆菌性膀胱炎。目的二：利用遗传学和生物化学的方法，研究FimX及其靶DNA序列的结构与功能关系。鉴于Fim重组酶在调节1型皮利表达中的核心作用，了解它们的功能和限制可能会为尿路感染的治疗和预防带来新的观点。