Post Translation Regulation in Mycobacteria

描述（由申请人提供）：关于致病性分枝杆菌感染宿主的机制知之甚少。此外，文献中几乎没有关于细菌在宿主环境中如何调节基因表达的信息。细菌病原体在宿主细胞内长期居住，也需要各种策略来帮助它们适应恶劣的环境条件。其中包括对应激条件的反应，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损伤。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控尚不清楚。在大肠杆菌中，已发现Lon蛋白酶参与应激反应的调节。除了作为受损蛋白的清道夫外，Lon还通过降解控制基因表达的细胞蛋白发挥重要的调节功能。Lon蛋白酶也被证明对流产布鲁氏菌在宿主中的存活很重要。最近，Lon已被证明通过蛋白水解hilA（致病性岛1，SP11的主要调节因子）表达所需的因子来调节沙门氏菌入侵相关基因的表达。在体外实验中，鼠伤寒沙门氏菌的离子失活导致其入侵肠道-407上皮细胞的能力显著增加。沙门氏菌离子的失活也与人巨噬细胞和小鼠中细菌的衰减有关。在感染的最初阶段，鸟分枝杆菌和结核分枝杆菌与宿主粘膜相互作用。在进入气道和肠道后，基因调控需要快速发生。虽然许多必需的基因似乎被宿主外环境中存在的条件上调，但许多其他基因却没有。我们的假设是，许多分枝杆菌毒力基因的调控可能受到能量依赖性调节蛋白酶（如Lon）的作用影响，即利用蛋白酶介导的翻译后调控来快速适应不同的条件。最近使用减法杂交的研究表明，Lon是鸟分枝杆菌与肠粘膜有效相互作用所必需的蛋白质。离子基因存在于鸟分枝杆菌和结核分枝杆菌的基因组序列中。因此，我们建议通过以下方法来获得分枝杆菌翻译后调控的新见解：1-确定M. avium（作为模式生物）中离子的过量产生和/或失活是否会影响巨噬细胞复制和侵袭粘膜上皮细胞的能力。这项工作有可能揭示分枝杆菌在宿主环境中调节毒力基因的机制。如果我们证实了我们的假设，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