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.

项目概要 致病菌利用多种过程引起人类疾病，这些过程包括生物膜形成、趋化性和运动性以及分泌系统的执行，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。医学上的几个 重要的细菌，包括一些人类致病性α变形菌，极难生长， 处理和/或操纵，因此，许多与过程相关的基本毒力机制 上述提到的这些在这些生物体中的定义不明确。因此，有很多好处，包括新颖的 治疗和疫苗的开发可以从定义广泛保守的细菌毒力机制中收集到。 考虑到 Alphaproteobacteria 的成员，即植物病原体根癌农杆菌 作为研究高度保守的基本毒力机制的典范模型 阿尔法变形菌，包括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，可以感知受伤植物释放的信号并做出反应，从而产生细菌趋化性 朝着受伤的植物。 A. tumefaciens 随后采用 IV 型分泌系统来转移 T- DNA复合物进入植物细胞。这种结合事件导致冠瘿瘤的形成， 这些都对植物造成严重损害。 初步结果表明，LysR 型转录调节因子 VtlR（毒力相关转录 LysR 家族调节因子）是根癌农杆菌介导的肿瘤有效形成所必需的。初步数据表明，根癌农杆菌 vtlR 缺失菌株在体内产生越来越少且不太坚固的肿瘤。 马铃薯与亲本品系相比，而且 vtlR 缺失品系表现出显着的缺陷 在生物膜的形成中。转录组分析表明，VtlR 控制一种称为 AbcR1 的小调节 RNA (sRNA) 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。密切相关的α流产布鲁氏菌变形杆菌中的VtlR直系同源物 是感染动物模型中毒力所必需的，因此，VtlR 家族调节因子高度保守，并且似乎是 Alphaproteobacteria 中宿主-细菌相互作用所必需的。因此， 根癌农杆菌中 VtlR 的系统表征将显着阐明其机制 这种转录调节因子与阿尔法变形菌的毒力有关。