Post Translation Regulation in Mycobacteria

描述(申请人提供)：对致病分枝杆菌感染宿主的机制知之甚少。此外，关于细菌如何在宿主环境中调节基因表达的文献中几乎没有任何信息。细菌病原体长期居住在宿主细胞内，也需要各种策略来帮助它们适应恶劣的环境条件。其中之一是对应激条件的反应，这表明细胞内病原体在宿主细胞内经历了相当数量的蛋白质错误折叠和破坏。同样，分枝杆菌基因和编码蛋白在与宿主粘膜和巨噬细胞相互作用时的调节也不是很清楚。Lon蛋白水解酶参与了大肠杆菌的应激反应的调节。除了作为受损蛋白质的清道夫外，Lon还通过降解控制基因表达的细胞蛋白质发挥重要的调节功能。LON蛋白水解酶对布鲁氏菌在宿主中的存活也起着重要作用。最近，Lon被证明通过蛋白分解Hila(致病性岛1，SP11)表达所需的因子来调节沙门氏菌入侵相关基因的表达。典型沙门氏菌中离子的灭活导致体外侵袭肠道-407上皮细胞的能力显著增加。沙门氏菌离子的灭活也与细菌在人巨噬细胞和小鼠体内的减弱有关。禽分枝杆菌和结核分枝杆菌在感染的初始阶段与宿主粘膜(S)相互作用。一旦进入呼吸道和肠道，基因调节需要以一种快速的方式发生。虽然一些必需的基因似乎受到寄主外环境中存在的条件的上调，但其他许多基因却没有。我们的假设是，许多分枝杆菌毒力基因的调控可能受到Lon等能量依赖性调节蛋白作用的影响，即利用蛋白酶介导的翻译后调节来快速适应不同的条件。最近使用消减杂交的研究表明，Lon是一种蛋白质，在禽类分枝杆菌和肠道粘膜之间的有效相互作用中是必需的。Ion基因存在于禽类分枝杆菌和结核分枝杆菌基因组序列中。因此，我们建议通过以下方式对分枝杆菌的翻译后调控获得新的见解：1-确定鸟分枝杆菌(作为模式生物)中离子的过度生产和/或失活是否影响在巨噬细胞中复制和入侵粘膜上皮细胞的能力。这项工作有可能揭示分枝杆菌用来调节宿主环境中毒力基因的机制。如果我们证实我们的假设，未来的工作将解决离子在结核分枝杆菌中的作用

DESCRIPTION (provided by applicant): Very little is known about the mechanisms by which pathogenic mycobacteria infect the host. In addition, there is almost no information in the literature on how the bacterium regulates gene expression in the host environment. Bacterial pathogens, which maintain long-term residence within the host cells, also need a variety of strategies to help them adapt to harsh environmental conditions. Among them is the response to stress conditions, suggesting that intracellular pathogens experience a considerable amount of protein misfolding and damage within host cells. Similarly, the regulation of mycobacterial genes and coded proteins upon interaction with the host mucosa, and within macrophages are not well known. Lon protease has been shown to participate in the regulation of stress responses in Escherichia coli. In addition to the function as scavenger of damaged proteins, Lon performs important regulatory functions by degrading cellular proteins that control gene expression. The Lon protease has also been shown to be important for Brucella abortus survival in the host. More recently, Lon has been demonstrated to regulate the expression of Salmonella invasion-related genes by proteolysis of factors required for hilA (a major regulator of the pathogenicity island 1, SP11) expression. Inactivation of Ion in Salmonella typnimurium leads to a significant increase in the ability to invade intestinal -407 epithelial cells in vitro. Inactivation of Salmonella Ion was also associated with attenuation of the bacterium in human macrophages and mice. Mycobacterium avium and M. tuberculosis interact with the host mucosa (s) at the initial stages of the infection. Upon entry into the airways and intestinal tract, gene regulation needs to occur in a rapid fashion. While a number of required genes appear to be up-regulated by conditions existing in the extra-host environment, many other genes are not. Our hypothesis is that the regulation of many mycobacterial virulence genes may likely be influenced by the action of energy dependent regulatory proteases such as Lon, i.e. using protease-mediated post-translational regulation to rapidly adapt to different conditions. Recent work using subtraction hybridization, suggests that Lon is a protein required for the efficient interaction between M. avium and the intestinal mucosa . The Ion gene is present in both M. avium and M. tuberculosis genome sequence. We, therefore, propose to gain new insight in the post-translational regulation in mycobacteria by: 1- Determining whether the overproduction and/or inactivation of Ion in M. avium (as a model organism) impacts the ability to replicate in macrophages and invade mucosal epithelial cells. This work has the potential to unveil mechanisms used by mycobacteria to regulate virulence genes in the environment of the host. In case we confirm our hypothesis, future work will address the role of Ion in M. tuberculosis