Characterizing the function and regulation of a conserved virulence-associated genetic pathway of pathogenic Alphaproteobacteria

致病性α变形菌保守毒力相关遗传途径的功能和调控特征

• 批准号: 10630575
• 负责人: Jason Eugene Heindl
• 金额: $ 3.15万
• 依托单位: SAINT JOSEPH'S UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2019
• 资助国家: 美国
• 起止时间: 2019-09-13 至 2022-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/10630575
• 关键词: Characterizing; function; regulation; conserved; virulence

PROJECT SUMMARY Pathogenic bacteria employ myriad processes to cause human disease, and these processes include biofilm formation, chemotaxis and motility, and the implementation of secretion systems, all of which ultimately aid in establishing intimate associations between the bacterium and the host. Several medically important bacteria, including some human pathogenic Alphaproteobateria, are extremely difficult to grow, handle, and/or manipulate, and thus, many of the basic virulence mechanisms related to the processes mentioned above are poorly defined in these organisms. Therefore, there are many benefits, including novel therapeutic and vaccine development that may be gleaned from defining broadly conserved bacterial virulence mechanisms. Considering members of the Alphaproteobacteria, the plant pathogen Agrobacterium tumefaciens serves as an exemplary model for studying basic virulence mechanisms that are highly conserved among the Alphaproteobacteria, including those causing human disease. A. tumefaciens is a free-living soil bacterium that senses and responds to signals released from wounded plants, resulting in bacterial chemotaxis toward the wounded plant. A. tumefaciens subsequently employs a type IV secretion system to transfer a T- DNA complex into the cells of the plant. This conjugation event leads to the formation of crown gall tumors, which are severely detrimental to the plant. Preliminary results indicate a LysR-type transcriptional regulator, VtlR (for virulence-associated transcriptional LysR-family regulator) is required for efficient A. tumefaciens-mediated tumor formation. Preliminary data demonstrate that an A. tumefaciens vtlR deletion strain produces fewer and less robust tumors in potatoes compared to the parental strain, and moreover, the vtlR deletion strain exhibits significant defects in biofilm formation. Transcriptomic analyses revealed that VtlR controls the expression of a small regulatory RNA (sRNA) called AbcR1, as well as a multitude of other genes related to conjugation systems, nutrient uptake, and virulence. The VtlR orthologue in the closely related alphaproteobacterium Brucella abortus is required for virulence in an animal model of infection, and thus, VtlR-family regulators are highly conserved and appear to be required for host-bacteria interactions in the Alphaproteobacteria. Therefore, the systematic characterization of VtlR in A. tumefaciens will significantly illuminate the mechanism by which this transcriptional regulator is linked to virulence in Alphaproteobacteria.

项目总结 病原菌利用多种过程引起人类疾病，这些过程包括生物膜的形成、趋化和运动以及分泌系统的实现，所有这些过程 最终有助于在细菌和宿主之间建立密切的联系。几个医学上的 重要的细菌，包括一些人类致病的甲型蛋白杆菌，极难培养， 处理，和/或操纵，因此，许多与过程相关的基本致病机制 上面提到的在这些生物体中的定义很差。因此，有很多好处，包括新奇的 从定义广泛保守的细菌毒力机制中可以收集到的治疗和疫苗开发。 考虑到α蛋白细菌的成员，植物病原菌根癌农杆菌 作为研究基本毒力机制的示范模型，这些机制在 甲型变形菌，包括那些引起人类疾病的细菌。根癌农杆菌是一种自由生活的土壤细菌，它能感知和响应受伤植物释放的信号，从而导致细菌的趋化性。 冲向受伤的植物。随后，根癌农杆菌利用IV型分泌系统将T- DNA复合体进入植物细胞。这种结合事件导致冠胆肿瘤的形成， 这对植物是非常有害的。 初步结果表明，一个LysR型转录调节因子VtlR(毒力相关转录调节因子)是根癌农杆菌介导的有效肿瘤形成所必需的。初步数据显示，根癌农杆菌vtlR缺失株在 与亲本菌株进行比较，而且vtlR缺失菌株表现出明显的缺陷 在生物膜形成过程中。转录分析表明，VtlR控制着一种称为AbcR1的小调控RNA(SRNA)的表达，以及与接合系统、营养吸收和毒力相关的许多其他基因的表达。近缘种布鲁氏菌中的VtlR同源基因 在感染的动物模型中，VtlR-家族调节子是毒力所必需的，因此，VtlR-家族调节子是高度保守的，似乎是甲蛋白细菌中宿主与细菌相互作用所必需的。因此， 根癌农杆菌VtlR的系统鉴定将显著阐明其作用机制 这种转录调节因子与甲型变形杆菌的毒力有关。