mazEF-mediated programmed cell death network in E. coli

描述(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体中的一种基本机制。1996年，我们报道了第一个在细菌中发现的与PCD有关的染色体毒素-抗毒素系统。这就是大肠杆菌的mazEF调节模块，其中mazF编码一种稳定的毒素，mazF编码一种不稳定的抗毒素，maze编码一种克服了mazF的致死作用的抗毒素。自1996年以来，我们在了解该系统的遗传、生化、结构和生理特性，以及它与应激条件的关系和一些著名抗生素的作用方面取得了相当大的进展。随着这项工作的继续，我们建议通过对一种新的群体感应细胞外死亡因子(EDF)的全面表征来扩展我们的研究，我们兴奋地发现EDF是E.ColimazEF介导的细胞死亡所必需的信号肽分子。我们的五个具体目标如下：1.鉴定E.coliEDF的确切化学成分；2.阐明EDF的作用机制；3.阐明EDF与MAZEF以及与大肠杆菌其他毒素-抗毒素系统的关系；4.鉴定EDF受体(S)系统；5.鉴定除大肠杆菌外的细菌的EDF。我们提出的EDF及其与细菌死亡的关系的综合研究将有助于理解一个独特的新的群体感应信号分子及其在细菌PCD中的重要性。此外，我们的结果还应该有助于阐明细菌交流的一个基本生物学现象，从而有助于阐明细菌种群的多细胞行为。实际上，我们的研究结果可能会作为一种新的策略的基础，以产生一种新的抗生素，引发细菌PCD，从而帮助解决已经成为公共卫生问题的问题。

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.