Structure and action of CARDS toxin

哮喘是一种复杂的疾病，以间歇性呼吸道阻塞和高反应性为特征，有时 伴随着呼吸道重塑。尽管哮喘的根本原因仍然知之甚少，但有一个 致病因素是接触呼吸道病原体。例如，支原体阳性的哮喘患者 肺炎支原体感染显示在抗生素治疗后肺功能有所改善。 治疗，而检测为阴性的患者则不治疗，这表明肺炎支原体之间存在因果关系 感染和哮喘症状严重程度。尽管肺炎支原体在临床上有很强的相关性 感染和哮喘病例的一个子集，直到最近，确定了一个可能发挥作用的毒力因素 在疾病方面，发病机制仍然难以捉摸。然而，当我们发现591个氨基酸后，这种情况就改变了。 肺炎分枝杆菌中具有ADP-核糖基转移酶(ART)活性的酸性蛋白 呼吸窘迫综合征毒素(卡片TX)。本提案中概述的实验旨在 使用一系列生物物理技术揭示卡片TX的结构和作用。使用成熟的 单晶X射线衍射仪，我们将测定：1)卡TX的三维结构；2) CardTx及其NAD“”辅助因子；3)CardTx与中和性单抗Fab形成的复合体 片段；4)TX与其细胞表面受体的重组胞外区的复合体 表面活性蛋白-A(SP-A)。一个更长期的目标是将这些3-D结构与信息结合使用 来自项目1和项目2，作为CARDS TX抑制剂的设计平台，这可能代表着新的 治疗哮喘和肺部炎症的治疗剂。

Asthma is a complex disorder characterized by episodic airway obstruction and hyper-responsiveness, sometimes accompanied by airway remodeling. Although the underlying causes of asthma remain poorly understood, one contributing factor is exposure to respiratory pathogens. For example, asthmatics positive for Mycoplasma pneumoniae (M. pneumoniae) infection have demonstrated an improvement in pulmonary function after antibiotic treatment whereas patients that test negative do not, suggesting a causal relationship between M. pneumoniae infection and asthma symptom severity. Although there is a strong clinical correlation between M. pneumoniae infection and a sub-set of asthma cases, until recently, the identification of a virulence factor that might play a role in disease pathogenesis had remained elusive. This situation changed, however, when we discovered a 591 amino acid protein with ADP-ribosyltransferase (ART) activity in M. pneumoniae designated Community Acquired Respiratory Distress Syndrome ToXin (CARDS TX). The experiments outlined in this proposal are designed to uncover the structure and action of CARDS TX using a range of biophysical techniques. Using the well-established tools of single crystal X-ray diffraction, we will determine: 1) the three-dimensional structure of CARDS TX; 2) CARDS TX in complex with its NAD"" co-factor; 3) CARDS TX in complex with neutralizing monoclonal antibody Fab fragments; and 4) CARDS TX in complex with recombinant extracellular domains of its cell surface receptor surfactant protein-A (SP-A). A longer term goal is to use these 3-D structures in conjunction with the information coming from Projects 1 and 2 as platforms for the design of CARDS TX inhibitors, which may represent novel therapeutic agents for the treatment of asthma and pulmonary inflammation.