mazEF-mediated programmed cell death network in E. coli

描述（由申请人提供）：程序性细胞死亡（PCD）被定义为导致细胞自杀的活跃过程，被认为是多细胞生物的基本机制。在1996年，我们报道了第一个发现的染色体毒素-抗毒素系统，负责细菌的PCD。这是大肠杆菌（E. coli）的mazEF可调节模块，其中mazF编码一种稳定的毒素mazF，而mazE编码一种不稳定的抗毒素mazE，后者克服了mazF的致命作用。自1996年以来，我们在了解这个系统的遗传、生化、结构和生理特性，以及它与应激条件和一些已知抗生素的作用的关系方面取得了相当大的进展。为了继续这项工作，我们建议通过全面表征一种新的群体感应细胞外死亡因子（EDF）来扩展我们的研究，我们很高兴地发现它是大肠杆菌mazef介导的细胞死亡所需的信号肽分子。我们的五个具体目标如下：1 .表征大肠杆菌EDF的确切化学成分；2. 阐明EDF的作用机制；3.阐明EDF与mazEF及大肠杆菌其他毒素-抗毒素系统的关系；4.描述EDF接收器系统的特性；5.对大肠杆菌以外细菌的edf进行表征。我们在此提出的对EDF及其与细菌死亡关系的综合研究将有助于理解一种独特的新型群体感应信号分子及其对细菌PCD的重要性。此外，我们的结果也应该有助于澄清细菌交流的基本生物学现象，从而阐明细菌群体的多细胞行为。实际上，我们的研究结果可以作为一种新策略的基础，以产生一种引发细菌PCD的新型抗生素，从而帮助解决已经成为公共卫生问题。

DESCRIPTION (provided by applicant): Programmed cell death (PCD), defined as an active process which results in cell suicide, is recognized as an essential mechanism in multicellular organisms. In 1996, we reported on the first chromosomal toxin-antitoxin system discovered to be responsible for PCD in bacteria. This was the Escherichia coli (E. coli) mazEF regulateable module in which mazF encodes a stable toxin, MazF, and mazE encodes a labile antitoxin, MazE, that overcomes the lethal effect of MazF. Since 1996, we have made considerable progress in understanding the genetic, biochemical, structural and physiological properties of this system, and its relation to stressful conditions and the action of some well known antibiotics. In continuation of this work, here we propose to extend our research by a comprehensive characterization of a novel quorum sensing Extra-cellular Death Factor (EDF) that we were excited to discover as being a signaling peptide molecule required for E. coli mazEF-mediated cell death. Our five specific aims are as follows: 1 to characterize the exact chemical composition of E. coli EDF; 2. to elucidate the mechanism of EDF action; 3.To elucidate the relation of EDF to mazEF and to E. coli other toxin-antitoxin systems; 4.To characterize the EDF receiver(s) system; 5.To characterize EDFs of bacteria other than E. coli. The integrative research on EDF and its relation to bacterial death that we propose here should contribute to the understanding of a unique novel quorum sensing signaling molecule and its importance to bacterial PCD. Moreover, our results should also help to clarify a fundamental biological phenomenon of bacterial communication and thereby the multicellular behavior of bacterial populations. Practically, the results of our study may be useful as a basis for a novel strategy for generating a new class of antibiotics that trigger bacterial PCD, and thereby to help what has become a public health problem.