cAMP signaling pathways within Mycobacterium tuberculosis

描述（由申请人提供）：结核分枝杆菌（Mtb）是结核病（TB）的病原体，继续在全球范围内对人类健康产生负面影响。该项目的长期目标是了解结核分枝杆菌在感染过程中感知和响应宿主环境的方式，从而开发出更好的结核病生物标志物和治疗方法。环AMP （cAMP）由腺苷酸环化酶产生，是微生物病原体及其哺乳动物宿主感知和响应环境信号的通用第二信使。cAMP通过与cAMP受体蛋白（CRP）样转录因子的变构相互作用，在结核分枝杆菌和其他细菌性病原体的毒力基因调控中发挥核心作用。结核分枝杆菌编码两种这样的转录因子：在小鼠模型中促进毒力的CrpMt；以及调节巨噬细胞内结核分枝杆菌基因表达的Cmr。先前的研究表明，Mtb细菌进入巨噬细胞后，cAMP水平急剧增加，这表明cAMP在巨噬细胞内环境的感知和响应中起作用。目前的项目解决了cAMP信号通过调节细菌内的基因表达以响应环境条件来促进mtb -宿主相互作用的假设。这一假设将在三个具体目标中得到解决。目的1将重新定义CrpMt调控及其在结核中的作用

DESCRIPTION (provided by applicant): Mycobacterium tuberculosis (Mtb), the causative agent of tuberculosis (TB), continues to negatively impact human health on a global scale. The long term goal of this project is to understand the means by which Mtb senses and responds to its host environment during infection, so that improved biomarkers and treatments for TB disease can be developed. Cyclic AMP (cAMP), which is generated from ATP by adenylyl cyclases, is a universal second messenger used by both microbial pathogens and their mammalian hosts to sense and respond to environmental cues. cAMP plays a central role in virulence gene regulation in Mtb and other bacterial pathogens through its allosteric interactions with cAMP receptor protein (CRP)-like transcription factors. Mtb encodes two such transcription factors: CrpMt, which contributes to virulence in a murine model; and Cmr, which regulates Mtb gene expression within macrophages. Previous work has shown that levels of cAMP within Mtb bacteria increase dramatically upon bacterial entry into macrophages, suggesting a role for cAMP in sensing and responding to the intra-macrophage environment. The current project addresses the hypothesis that cAMP signaling contributes to Mtb-host interactions by regulating gene expression within the bacterium in response to environmental conditions. This hypothesis will be addressed in three specific aims. Aim 1 will redefine the CrpMt regulon and its role in Mtb biology during infection at the global, cellular and molecular levels. Aim 2 addresses the role of Cmr in Mtb biology with a focus on its role in regulating propionate metabolism during macrophage infection and within granulomas. Aim 3 addresses the roles of CrpMt and Cmr as co-regulators with other transcription factors, of the espA virulence operon using a combination of molecular, genetic and cellular approaches. Completion of these studies will significantly advance understanding of cAMP's role in Mtb biology, particularly in the context of bacterial sensing and response to host-associated conditions. This information will contribute to the identification of stage-specific biomarkers of infection and new drug targets. The significance of this project is further enhanced by cAMP's established role in regulating virulence in a wide range of important bacterial pathogens, as well as the exceptionally large and unusual network of cAMP-associated signaling proteins in Mtb.