GLOBAL CONSEQUENCES OF INTERRUPTION OF MICROBIAL AUTOINDUCER SIGNALING

这个子项目是许多利用资源的研究子项目之一 由NIH/NCRR资助的中心拨款提供。子项目的主要支持 而子项目的主要调查员可能是由其他来源提供的， 包括其它NIH来源。 列出的子项目总成本可能 代表子项目使用的中心基础设施的估计数量， 而不是由NCRR赠款提供给子项目或子项目工作人员的直接资金。 细菌分泌各种信号分子，使它们能够协调基因表达，并表现为多细胞生物。 响应于这些“群体感应”或“自诱导物”信号，诸如毒力因子表达、生物膜形成和耐药性等医学上重要的表型以群体广泛的方式被调节。 酶5'甲基硫代腺苷/S-腺苷高半胱氨酸核苷酶（MTA/SAH核苷酶，MTN）在导致自诱导物I（AI-1）和自诱导物II（AI-2）形成的生物合成途径中占据中心位置。 此外，MTN在S-腺苷甲硫氨酸依赖性多胺合成和甲基化反应期间消耗的甲硫氨酸和腺嘌呤的再循环中控制关键步骤。MTN的药理学或遗传抑制应阻断甲硫氨酸和嘌呤补救，通过抑制性MTA和SAH核苷的积累引起生长延迟，并干扰自诱导物合成和下游信号依赖性过程。 为了研究这种酶在营养补救和信号通路中的作用，用MTN敲除的大肠杆菌菌株。大肠杆菌（O 157：H7）和肺炎克雷伯氏菌（Klebsiella pneumoniae）的感染，并在体外感染模型和鼠体内定殖和毒力模型中研究其生长（速率、碳利用、生物膜形成）、哺乳动物细胞侵袭减弱的改变。 MTN基因缺失的蛋白质组学和代谢组学适应也将通过LC/MS和NMR进行检查，以进一步表征酶中断的分子后果，并解释观察到的表型改变的基础。 最终，这些实验应该强调细菌中细胞信号传导作为新型抗生素开发靶点的重要性。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. Bacteria secrete a variety of signaling molecules that allow them to coordinate gene expression and behave as multicellular organisms. In response to these 'quorum sensing' or 'autoinducer' signals, such medically important phenotypes as virulence factor expression, biofilm formation, and drug resistance are modulated in a population wide manner. The enzyme 5' Methylthioadenosine / S-adenosylhomocysteine nucleosidase (MTA/SAH nucleosidase, MTN) occupies a central place in the biosynthetic pathways that lead to both autoinducer I (AI-1) and autoinducer II (AI-2) formation. In addition, MTN governs a crucial step in the recycling of methionine and adenine consumed during S-adenosylmethionine dependent polyamine synthesis and methylation reactions. Pharmacologic or genetic inhibition of MTN should block methionine and purine salvage, cause growth delays through the accumulation of inhibitory MTA and SAH nucleosides, and interfere with autoinducer synthesis and downstream signal dependent processes. To examine the role of this enzyme in nutrient salvage and signaling pathways, MTN knock-out strains of E. coli (O157:H7) and Klebsiella pneumoniae will be created and studied for alterations in growth (rate, carbon utilization, biofilm formation), attenuation of mammalian cell invasion in in vitro models of infection, and in murine models of in vivo colonization and virulence. Proteomic and metabolomic adaptations to MTN gene deletion will also be examined by LC/MS and NMR to further characterize the molecular consequences of enzyme interruption and explain the basis for observed alteration in phenotype. Ultimately, these experiments should underscore the importance of cellular signaling in bacteria as a target for novel antibiotic development.