Sigma factor networks of M. tuberculosis

描述（由申请人提供）：细菌应激反应的一个关键方面是通过改变σ因子（一种决定启动子特异性的亚基）来重编程RNA聚合酶（RNAP）。用RNAP全酶中的另一个σ因子取代一个σ因子，导致迄今沉默的细胞功能的表达。这些新表达的功能导致细菌适应新的环境条件和生存所需的代谢，形态和生理变化。人类病原体结核分枝杆菌建立和传播感染的能力与广泛的基因表达重编程密切相关，该基因表达重编程允许该微生物在感染期间在复制（生长）和非复制（休眠）状态之间切换。复杂基因调控的需要反映在M中所见的最高辅助σ因子/基因组大小比中。结核病属于专性病原体。我们工作的前提是了解M.结核病需要阐明这种微生物的西格玛因子的生物学。sigma因子生物学的核心是sigma因子之间的调节相互作用，其是转录的和转录后的。在目前的R21应用中，我们建议重建sigma因子转录网络的架构，并测试网络对压力条件的响应。实验方法是围绕三个目标，其特点是测试网络的复杂性不断增加。这些措施是：（1）确定M之间的直接调节相互作用。结核σ因子在大肠杆菌中表达。（2）探讨σ因子基因的非胁迫响应激活对M. coli中下游σ因子基因表达的影响。结核病，以及（3）表征暴露于抑菌应激物后的西格玛网络反应。成功完成的目标将使我们能够确定所有的直接和间接的转录之间的相互作用的西格玛因素，并产生一个更大的，多尺度的监管网络，将包括转录后控制西格玛因子的活动和参与额外的类的压力传感和调节因子的未来重建的假设。西格玛因子网络的充分知识，预计将确定西格玛因素的一部分，发展之间的增长和休眠开关。这些sigma因子（以及控制其表达和活性的调节途径）成为抗结核干预的潜在靶点。 公共卫生相关性：本研究的目的是在人类病原菌M中重建σ因子的转录调控网络，该因子介导细菌对环境的适应和对应激的反应。肺结核，肺结核的病原体。描述这个网络将有助于定义关于改变病原体对压力的反应能力和在各种环境中生存的假设。

DESCRIPTION (provided by applicant): A critical aspect of the bacterial stress response is the reprogramming of RNA polymerase (RNAP) by changing the sigma factor, a subunit that determines promoter specificity. Substituting one sigma factor with another in the RNAP holoenzyme results in the expression of hitherto silent cellular functions. These newly expressed functions lead to the metabolic, morphological, and physiological changes that are required for bacterial adaptation to the new environmental conditions and survival. The ability of the human pathogen Mycobacterium tuberculosis to establish and transmit infection is tightly associated with the extensive gene expression reprogramming that allows this microorganism to switch between replicating (growth) and nonreplicating (dormancy) states during infection. The need for complex gene regulation is reflected in the highest accessory sigma factor/genome size ratio seen in M. tuberculosis among obligate pathogens. The premise of our work is that understanding the stress response of M. tuberculosis requires elucidating the biology of this microorganism's sigma factors. Central to sigma factor biology are the regulatory interactions among sigma factors, which are transcriptional and post-transcriptional. In the present R21 application, we propose to reconstruct the architecture of the sigma factor transcriptional network and to test the network response to stress conditions. The experimental approach is built around three aims, which are characterized by the increasing complexity of the network tested. These are: (1) to identify direct regulatory interactions between M. tuberculosis sigma factors expressed in E. coli, (2) to assess the effect of stress-response independent activation of sigma factor genes on the expression of downstream sigma factor genes in M. tuberculosis, and (3) to characterize the sigma network response following exposure to bacteriostatic stressors. Successful completion of the aims will enable us to identify all the direct and indirect transcriptional interactions between sigma factors and to generate hypotheses toward future reconstruction of a larger, multi-scale regulatory network that will include post-transcriptional control of sigma factor activity and the involvement of additional classes of stress-sensing and regulatory factors. Full knowledge of the sigma factor network is expected to identify sigma factors that are part of the developmental switch between growth and dormancy. These sigma factors (and the regulatory pathways controlling their expression and activity) become potential targets for anti-tuberculosis intervention. PUBLIC HEALTH RELEVANCE: This proposal aims to reconstruct the transcriptional regulatory network of sigma factors, which mediate bacterial adaptation to the environment and response to stress, in the human pathogen M. tuberculosis, the causative agent of tuberculosis. Characterizing this network will help define hypotheses about ways to alter the pathogen's ability to respond to stress and survive in a variety of environments.