MECHANISM OF VIRULENCE REGULATION BY MEMBRANE ACTIVATORS

描述(改编自申请人的摘要)： 转录的启动通常是由 作用于碱基的启动子特异性转录因子 转录装置。通常情况下，这些因子是可溶性蛋白质。 与RNA聚合酶的特定成分相互作用。 几种毒力基因在弧菌中的转录 霍乱受两种膜定位活化子ToxR和ToxR的调节 TCPP，每一种都需要特定的效应蛋白，ToxS和TcpH， 它们的功能不明确，但也是膜定位的。 目前对这种病原体进行协调调控的模式是 ToxR和TCPP共同激活编码基因的转录 另一种激活剂，ToxT，然后激活基因的表达 编码霍乱毒素、毒素共调控的菌毛和附件 殖民因素。该模型还提出，ToxR，独立 在TCPP中，同时激活ompU和抑制ompT的表达。 迪丽塔博士建议进行基因和生化实验，目的是 ToxR和TCPP调控基因表达的机制分析 霍乱弧菌。拟议工作的目标是：1)确定 ToxR和TCPP激活ToxT转录的分子基础 2)确定ToxR和TCPP介导的调节的意义 体内通过重新编程toxT、ompU和ompT基因的表达；3) 分析ToxR和TCPP与转录机制的相互作用 验证这些膜蛋白激活转录的假设 直接；4)表征ToxR依赖的ompU激活；以及5) 膜定位在ToxR和TCPP中的重要性研究 功能。ToxR和TCPP等膜定位激活剂已被 在其他革兰氏阴性菌中发现，包括一些病原体。 因此，成功实现这些目标将有助于 更好地理解一个不断壮大的不同寻常和 重要的转录因子。

DESCRIPTION (Adapted from the Applicant's Abstract): Transcriptional initiation is often controlled by the action of promoter-specific transcription factors acting on the basal transcription apparatus. Typically these factors are soluble proteins that interact with specific components of RNA polymerase. Transcription of several virulence genes in the bacterium Vibrio cholerae is regulated by two membrane-localized activators, ToxR and TcpP, each of which requires specific effector proteins, ToxS and TcpH, which have an unclear function but which are also membrane-localized. The current model for coordinate regulation in this pathogen is that ToxR and TcpP cooperate to activate transcription of the gene encoding another activator, ToxT, which then activates expression of genes encoding cholera toxin, toxin-coregulated pilus and accessory colonization factor. The model also proposes that ToxR, independently of TcpP, simultaneously activates ompU and represses ompT expression. Dr. DiRita proposes genetic and biochemical experiments aimed at analyzing the mechanism of how ToxR and TcpP control gene expression in V. cholerae. The aims of the proposed work are: 1) to determine the molecular basis for transcription activation of toxT by ToxR and TcpP; 2) to determine the significance of ToxR and TcpP-mediated regulation in vivo by reprogramming toxT, ompU and ompT gene expression; 3) to analyze ToxR and TcpP interaction with the transcription machinery to test the hypothesis that these membrane proteins activate transcription directly; 4) to characterize ToxR-dependent activation of ompU; and 5) to study the importance of membrane localization in ToxR and TcpP function. Membrane-localized activators like ToxR and TcpP have been identified in other Gram negative bacteria, including some pathogens. Successful completion of these aims will therefore contribute to a greater mechanistic understanding of a growing family of unusual and important transcription factors.