Mechanisms of Anthrax Virulence Factor AtxA.

描述(申请人提供)：炭疽芽孢杆菌质粒携带的基因atxa编码炭疽毒素表达的主要调节因子。虽然它在毒力中的作用已经从基因上得到了证实，但其作用的机制细节仍然不清楚。我们发现其产物Atxa在体内与炭疽RNA聚合酶结合，并在体外证明了其转录活性。利用我们在阐明各种细菌调控基因表达的结构和生化机制方面的广泛和在许多方面的独特经验，我们提出了一个全面的Atxa结构和功能研究计划。作为拟议研究的结果，将出现对Atxa在炭疽毒素表达中的作用的详细了解，包括对其作用的分子机制的深入研究，对该因子的差异磷酸化与其转录活性之间的相互作用的彻底分析，以及该因子在“开”和“关”状态下的高分辨率结构。总之，这些见解将有助于更好地了解炭疽病的毒力和致病性，同时作为基于结构的设计的起点，以Atxa为基础设计这种重要的人畜共患病原体和A类病原体产生炭疽毒素的基于Atxa的抑制剂。 公共卫生相关性：炭疽芽孢杆菌是人畜共患炭疽病感染的常见原因，在美国本土已被用作生物恐怖武器。我们提出了炭疽病毒毒力和毒素产生的主要调控因子转录因子Atxa的全面生化和结构研究计划。作为这项研究的结果，将出现对Atxa作用机制的详细了解，同时将收集必要的结构和生化信息，作为基于知识的药物设计的目标进行评估。

DESCRIPTION (provided by applicant): Bacillus anthracis plasmid-borne gene atxA encodes a major regulator of anthrax toxin expression. Although its role in virulence has been confirmed genetically, the mechanistic details of its action remain obscure. We have discovered that its product, AtxA, binds to anthrax RNA polymerase in vivo, and demonstrated its transcriptional activity in vitro. Using our extensive and in many ways unique experience in elucidating structural and biochemical mechanisms of various bacterial regulators of gene expression we propose a comprehensive plan of AtxA structural and functional research. As a result of the proposed research a detailed understanding of AtxA role in the expression of the anthrax toxin will emerge, complete with in-depth investigation of the molecular mechanism of its action, thorough analysis of the interplay between the differential phosphorylation of this factor and its transcriptional activity, and a high resolution structure of this factor in the "ON" and "OFF" states. Altogether these insights would allow for a better understanding of anthrax virulence and pathogenicity, while serving as a starting point of the structure-based design of AtxA-based inhibitors of anthrax toxin production by this important zoonotic pathogen and a Category A agent. PUBLIC HEALTH RELEVANCE: Bacillis anthracis is a routine cause of zoonotic anthrax infections and has been used as a bioterrorist weapon on the US soil. We propose a comprehensive plan of biochemical and structural research of the main regulator of anthrax virulence and toxin production, transcription factor AtxA. As the result of this research, a detailed understanding of AtxA mechanism of action will emerge while necessary structural and biochemical information will be gathered for its evaluation as a target for knowledge-based drug design.