Virulence Gene Expression by Bacillus anthracis

描述（由申请人提供）：该提案重点关注炭疽芽孢杆菌毒力基因控制，重点关注主要毒力基因调节因子AtxA的表达和功能。B。炭疽菌是一种发育中的细菌，以两种不同的生理状态存在，即代谢活跃的营养细胞和休眠孢子。孢子-营养细胞周期在发病机制中具有根本的重要性.孢子进入哺乳动物宿主并发芽成为营养细胞。在感染期间，B.炭疽菌保持营养状态并合成荚膜、炭疽毒素蛋白和其他促进发病的因子;不形成孢子。然而，当宿主死亡时，营养细胞暴露于环境中，毒素和荚膜不产生，B。炭疽菌产孢效率高。因此，毒力因子的合成和产孢之间的反比关系对炭疽致病具有重要的生理意义。这两个过程之间的主要联系是AtxA。我们实验室和其他实验室的研究揭示了毒力基因表达的主要多效性调节因子与分批培养中生长的细胞的生理状态之间的关系。B。炭疽菌的发育调节剂同源物，其在非致病性芽孢杆菌属物种B中已被充分表征。枯草芽孢杆菌与atxA的转录有关。此外，AtxA功能似乎是由翻译后修饰和宿主相关信号控制的。在这项工作中，我们将（1）进行AtxA的功能分析，（2）确定控制atxA表达的分子机制，（3）建立atxA调节剂的生理相关性和AtxA蛋白在炭疽病中的特定功能修饰。B。炭疽病是A类选择剂，并且针对炭疽病的更有效的化学疗法、疫苗和诊断的开发是国家优先事项。定义和表征B.炭疽菌控制毒力基因的表达将推进我们对B的基本理解。探讨炭疽病的发病机理，为制定合理的炭疽病防治对策提供依据。此外，关于新的调节器AtxA的分子功能的信息将有助于我们对基因调控机制的全面理解。最后，本研究获得的信息可以应用于其他感染因子，因为B。炭疽是宿主-病原体相互作用、细菌中的环境信号传导和细菌生理学的其它方面的多个特征的理想模型。 公共卫生相关性：B。炭疽病是A类选择剂，并且针对炭疽病的更有效的化学疗法、疫苗和诊断的开发是国家优先事项。定义和表征B.炭疽菌控制毒力基因的表达将推进我们对B的基本理解。探讨炭疽病的发病机理，为制定合理的炭疽病防治对策提供依据。B中毒素和荚膜基因表达的分子基础的探索。炭疽病与评估关键调节因子的重要性的动物研究相结合将填补关于B的空间和时间性质的知识的关键空白。炭疽病的发展和毒力因子在宿主体内的合成。此外，本研究中获得的信息可以应用于其他感染因子，因为B。炭疽是宿主-病原体相互作用、细菌中的环境信号传导和细菌生理学的其它方面的多个特征的理想模型。

DESCRIPTION (provided by applicant): This proposal focuses on Bacillus anthracis virulence gene control, with emphasis on the expression and function of the major virulence gene regulator AtxA. B. anthracis is a developmental bacterium existing in two distinct physiological states, metabolically active vegetative cells and dormant spores. The spore - vegetative cell cycle is of fundamental importance in pathogenesis. Spores enter a mammalian host and germinate to become vegetative cells. During infection, B. anthracis remains vegetative and synthesizes capsule, anthrax toxin proteins, and other factors that facilitate pathogenesis; sporulation does not occur. However, upon death of the host when vegetative cells are exposed to the environment, toxins and capsule are not produced and B. anthracis sporulates efficiently. Thus, the inverse relationship between virulence factor synthesis and sporulation is physiologically significant for anthrax pathogenesis. The major link between these two processes is AtxA. Investigations in our laboratory and others have revealed a relationship between this major pleiotropic regulator of virulence gene expression and the physiological state of cells grown in batch culture. B. anthracis homologues of developmental regulators that have been well-characterized in the non- pathogenic Bacillus species B. subtilis have been linked to transcription of atxA. Moreover, AtxA function appears to be controlled by post-translational modification and host-associated signals. In this work, we will (1) perform functional analyses of AtxA, (2) determine molecular mechanisms for control of atxA expression, and (3) establish the physiological relevance of atxA regulators and specific functional modifications of the AtxA protein in anthrax disease. B. anthracis is a Category A Select Agent and the development of more effective chemotherapeutics, vaccines, and diagnostics for anthrax disease is a national priority. Defining and characterizing the molecular mechanisms by which B. anthracis controls virulence gene expression will advance our fundamental understanding of B. anthracis pathogenesis and facilitate a rational approach for the development of anthrax countermeasures. Furthermore, information regarding the molecular function of the novel regulator AtxA will contribute to our overall understanding of mechanisms of gene regulation. Finally, information obtained in this study can be applied to other infectious agents because B. anthracis is an ideal model for multiple features of host-pathogen interactions, environmental signaling in bacteria, and other aspects of bacterial physiology. PUBLIC HEALTH RELEVANCE: B. anthracis is a Category A Select Agent and the development of more effective chemotherapeutics, vaccines, and diagnostics for anthrax disease is a national priority. Defining and characterizing the molecular mechanisms by which B. anthracis controls virulence gene expression will advance our fundamental understanding of B. anthracis pathogenesis and facilitate a rational approach for the development of anthrax countermeasures. Exploration of the molecular basis for toxin and capsule gene expression in B. anthracis in combination with animal studies assessing significance of key regulators will fill a critical gap in knowledge regarding the spatial and temporal nature of B. anthracis development and virulence factor synthesis within the host. Furthermore, information obtained in this study can be applied to other infectious agents because B. anthracis is an ideal model for multiple features of host-pathogen interactions, environmental signaling in bacteria, and other aspects of bacterial physiology.