GLOBAL CONSEQUENCES OF INTERRUPTION OF MICROBIAL AUTOINDUCER SIGNALING

这个子项目是许多研究子项目中利用 资源由NIH/NCRR资助的中心拨款提供。子项目和 调查员(PI)可能从NIH的另一个来源获得了主要资金， 并因此可以在其他清晰的条目中表示。列出的机构是 该中心不一定是调查人员的机构。 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体。作为对这些“群体感应”或“自身诱导子”信号的响应，毒力因子的表达、生物膜的形成和耐药性等医学上重要的表型以群体范围的方式被调节。5‘-甲硫腺苷/S-腺苷-同型半胱氨酸核苷酶(MTA/SAH核苷酶，MTN)在生物合成途径中占有中心地位，该酶可导致自身诱导物I(AI-1)和自身诱导物II(AI-2)的形成。此外，MTN在S-腺苷蛋氨酸依赖的多胺合成和甲基化反应中消耗的蛋氨酸和腺嘌呤的循环利用中起着至关重要的作用。MTN的药理或遗传抑制应阻止蛋氨酸和嘌呤的挽救，通过抑制的MTA和SAH核苷的积累而导致生长延迟，并干扰自身诱导物的合成和下游信号依赖的过程。为了检测这种酶在营养挽救和信号通路中的作用，将创建MTN基因敲除的大肠杆菌(O157：H7)和肺炎克雷伯菌，并在感染的体外模型和小鼠体内定植和毒力模型中研究生长(速率、碳利用、生物膜形成)、减弱哺乳动物细胞侵袭的变化。蛋白质组和代谢组学对MTN基因缺失的适应性也将通过LC/MS和核磁共振进行检测，以进一步表征酶中断的分子后果，并解释观察到的表型变化的基础。最终，这些实验应该强调细菌中细胞信号作为新抗生素开发目标的重要性。

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. 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.