HOLOLUXP:LUXQ

该子项目是利用 由NIH/NCRR资助的中心赠款提供的资源。子项目和 研究者（PI）可能从另一个NIH来源获得主要资金， 因此可以在其他CRISP条目中表示。列出的机构是 中心，不一定是研究者的机构。 细胞外信号分子自诱导物-2（AI-2）介导不同细菌物种的群体感应通讯。在海洋弧菌中，AI-2与周质受体LuxP的结合调节内膜传感器激酶LuxQ的活性，将AI-2信息转导到细胞质中。在低细胞密度下，当LuxP不与AI-2结合时，LuxQ充当激酶，而在高细胞密度下，当LuxP与AI-2结合时，LuxQ充当磷酸酶。我们已经表明，哈维氏弧菌LuxP协会组成与LuxQ在AI-2的存在和不存在。1.9分¿¿ apoLuxP与LuxQ的周质结构域复合的X射线晶体结构显示，后者包含两个串联PAS（Per/ARNT/Simple-minded）折叠。因此，尽管许多原核PAS折叠本身结合配体，但LuxQ周质PAS折叠反而结合LuxP，监测其AI-2占有率。破坏apoLuxP：LuxQ界面的突变使哈维氏弧菌对AI-2敏感，这意味着AI-2结合导致一组LuxP：LuxQ接触被另一组替换。这些构象变化使LuxQ在两种相反的酶活性之间切换，每种酶活性都向细胞质传递有关周围环境细胞密度的信息。 比较载脂蛋白复合物和holo复合物（本文提出）的结构将揭示AI-2诱导的构象变化，因此，AI-2信号调节的机制。 细菌通过一种称为群体感应的机制来调节基因表达以响应细胞密度的变化。 这种密度触发的反应导致细菌群体内协调的表型变化。 群体感应指导包括毒力因子表达、生物膜发育、生物发光、抗生素产生和DNA交换的过程。 我们的研究将有助于合理设计广谱抗菌化合物，干扰群体感应。 发现这些化合物是至关重要的，因为细菌越来越对当前的抗菌治疗产生耐药性。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. The extracellular signal molecule autoinducer-2 (AI-2) mediates quorum sensing communication in diverse bacterial species. In marine vibrios, binding of AI-2 to the periplasmic receptor LuxP modulates the activity of the inner membrane sensor kinase LuxQ, transducing the AI-2 information into the cytoplasm. At low cell density, when LuxP is not bound to AI-2, LuxQ functions as a kinase, whereas at high cell density, when LuxP is bound to AI-2, LuxQ acts as a phosphatase. We have shown that Vibrio harveyi LuxP associates constitutively with LuxQ in both the presence and absence of AI-2. The 1.9 ¿¿¿ x-ray crystal structure of apoLuxP, complexed with the periplasmic domain of LuxQ, reveals that the latter contains two tandem PAS (Per/ARNT/Simple-minded) folds. Thus, although many prokaryotic PAS folds themselves bind ligands, the LuxQ periplasmic PAS folds instead bind LuxP, monitoring its AI-2 occupancy. Mutations that disrupt the apoLuxP:LuxQ interface sensitize V. harveyi to AI-2, implying that AI-2 binding causes the replacement of one set of LuxP:LuxQ contacts with another. These conformational changes switch LuxQ between two opposing enzymatic activities, each of which conveys information to the cytoplasm about the cell density of the surrounding environment. Comparison of the apo complex and holo complex (proposed here) structures will reveal AI-2-induced conformational changes, and therefore, the mechanism of AI-2 signaling regulation. Bacteria modulate gene expression in response to changes in cell density via a mechanism termed quorum sensing. This density-triggered response results in coordinated phenotypic changes within bacterial populations. Quorum sensing directs processes including virulence factor expression, biofilm development, bioluminescence, antibiotic production, and DNA exchange. Our studies will facilitate the rational design of broad-spectrum antibacterial compounds that interfere with quorum sensing. Discovery of such compounds is critical as bacteria increasingly become resistant to current antimicrobial therapies.