Differential regulation of three DMSO reductases during enteric salmonellosis

项目摘要 非伤寒沙门氏菌是成功的食源性病原体，部分原因是它们能够利用多种 营养来源，以支持疾病在许多主机。在哺乳动物的肠道内，有机硫的催化剂 宿主和/或微生物群产生的化合物可导致电子受体二甲基亚砜的产生 （DMSO）。大肠杆菌K12是一种密切相关的肠道共生细菌，其基因组编码一个共- 转录操纵子致力于DMSO（dmsABC）的厌氧还原，并已被用作模型 系统研究DMSO呼吸在肠杆菌科。相比之下，引起肠道疾病的沙门氏菌血清型 疾病编码三个操纵子同源的dmsABC，这表明这条途径是重要的，以支持健身 在肠道内。我们先前的工作表明，DMSO减少是一个生物学相关的途径，以支持 沙门氏菌适应急性肠道定植。体外表型分析表明STM 0964是主要的 DMS 0还原酶的催化亚基dmsA的同源物，而STM 4305作为替代的dmsA同源物 在厌氧生长期间。然而，在我们对细菌如何调节的理解方面存在着一个关键的差距， 每种DMSO还原酶的使用以及每种DMSO还原酶如何在肠道感染期间促进适应性。 厌氧呼吸途径中的遗传冗余是肠杆菌科中的一个共同主题， 细菌受益于营养供应的变化，以调节肠道的健康。我的初步数据显示 DMSO增加了替代的dmsA同源物STM 4305的启动子活性。的启动子活性 优势dmsA同源物STM 0964类似于E. coli dmsA，表明 沙门氏菌具有一个新的机制，转录调控DMSO。我假设 DMSO还原酶的差异活化支持肠道内沙门氏菌的适应性。在Aim I，我会 建立DMSO介导的替代DMSO还原酶的转录调节机制， 生物化学、遗传学和RNA测序方法。在目标II中，我将利用荧光显微镜， 竞争性感染，以阐明每种DMSO还原酶在牛肠道感染过程中的作用 主持人拟议的工作将整合我的兽医培训与肠道疾病的大型动物模型， 先进的基因表达分析，以确定沙门氏菌如何受益于明显的遗传冗余， DMSO还原。在完成奖学金培训后，我将做好准备在职业生涯中取得成功， 独立的临床科学家，在遗传方法和动物建模方面具有专业知识，以研究传染病 一种健康意义的疾病。

PROJECT SUMMARY Non-typhoidal Salmonella are successful foodborne pathogens in part because of their ability to utilize diverse nutrient sources to support disease in many hosts. Within the mammalian gut, catabolism of organosulfur compounds by the host and/or the microbiota can lead to production of the electron acceptor dimethyl sulfoxide (DMSO). The genome of Escherichia coli K12, a closely related gut-commensal bacterium, encodes a single co- transcribed operon dedicated to the anaerobic reduction of DMSO (dmsABC) and has been used as a model system to study DMSO respiration in Enterobacteriaceae. In contrast, Salmonella serotypes that cause enteric disease encode three operons homologous to dmsABC, suggesting this pathway is important to support fitness within the gut. Our prior work demonstrates that DMSO reduction is a biologically relevant pathway to support Salmonella fitness during acute intestinal colonization. In vitro phenotyping suggests STM0964 is the dominant homolog of dmsA, the catalytic subunit of a DMSO reductase, while STM4305 acts an alternate dmsA homolog during anaerobic growth. However, there is a critical gap in our understanding of how the bacterium regulates the use of each DMSO reductase and how each DMSO reductase contributes to fitness during enteric infection. Genetic redundancy in anaerobic respiration pathways is a common theme in Enterobacteriaceae that allows bacteria to benefit from changes in nutrient availability to regulate fitness in the gut. My preliminary data shows that DMSO increases the promoter activity of the alternate dmsA homolog, STM4305. The promoter activity of the dominant dmsA homolog, STM0964, is not activated by DMSO akin to E. coli dmsA, suggesting that Salmonella possesses a novel mechanism for transcriptional regulation by DMSO. I hypothesize that differential activation of DMSO reductases supports Salmonella fitness within the gut. In Aim I, I will establish a mechanism for DMSO-mediated transcriptional regulation of the alternate DMSO reductase using biochemical, genetic and RNA sequencing approaches. In Aim II, I will utilize fluorescence microscopy and competitive infections to elucidate the contribution of each DMSO reductase during enteric infection of the bovine host. The proposed work will integrate my veterinary training with large animal modeling of enteric disease and advanced gene expression analysis to establish how Salmonella benefits from apparent genetic redundancy in DMSO reduction. At the completion of fellowship training, I will be poised for success in a career as an independent clinician-scientist with expertise in genetic approaches and animal modeling to study infectious diseases of One Health significance.