Global Circuitry that Controls Acinetobacter Resistance and Virulence

项目总结 鲍曼不动杆菌是已知的最具抗药性的病原体之一， 毒力增强的分离株的出现对公共卫生构成了紧迫的挑战。理解 微生物如何通过其保护性的细胞膜来阻止抗生素和免疫攻击是至关重要的 制定控制这一威胁的新战略。细菌的包膜合成和完整性是 通常由控制信封特定方面的大量响应系统维护。一个。 然而，鲍曼尼与这一范式有很大的不同。这种病原体缺少许多同源基因。 规范的包膜反应蛋白，而不是依赖于单一的双蛋白调控系统来 全局调节包膜的每一层，并控制抗生素耐药性和 引发疾病。这一独特的系统被称为BfmRS，它降低了对多种药物的敏感性， 对抗先天免疫杀死，促进小鼠的致命性疾病的发展。有趣的是，一个 显示出增强毒力的临床分离株需要系统生长。因此，Bfmr紧密相连。 与病原体感染的难治性有关，并代表着一个关键的潜在治疗目标。尽管 它的根本重要性，我们缺乏对大的BfmRS规则如何控制广泛的- 范围耐药性和致病性，以及系统感知的信号。该计划的目标是 拟议的研究是为了了解鲍曼不动杆菌是如何使用单个控制电路同时 调节抗性和毒力。我们的中心假设是BfmRs共同控制着两者的屏障。 通过调节关键外膜(OM)结构水平实现药物渗透和先天免疫攻击 以应对被膜蛋白生产中断的情况。我们将通过追求三个方面来检验这一假设 AIMS，它建立在我们定义BfmRS调节子及其化学成因的广泛初步数据的基础上 以及它用于信号转导的磷酸化级联反应。在目标1中，我们将测试该模型 BfmRS通过调节细菌与抗生素和天然免疫效应物的界面来控制细菌与抗生素的界面 OM屏障。在目标2中，我们将识别抗生素诱导的和内在的应激信号，这些信号是由 BfmRS。在目标3中，我们将定义BfmRs活动可变性、生长依赖、 以及不同患者分离株的毒力作为对BfmRS信号水平变异是 侵袭性菌株毒力增强的驱动力。这项工作将阐明一种 独特的调控系统控制着至关重要的医院内的耐药性和致病性 微生物。这些结果将为加强抗生素和免疫杀灭作用的策略提供依据 广泛耐药的细菌。

PROJECT SUMMARY Acinetobacter baumannii is among the most antibiotic-resistant pathogens known, and the emergence of isolates with enhanced virulence poses an urgent public health challenge. Understanding how the microorganism thwarts antibiotic and immune attack via its protective cell envelope is essential to developing new strategies for controlling this threat. Envelope synthesis and integrity in bacteria are typically maintained by a large number of response systems that control specific aspects of the envelope. A. baumannii, however, has diverged substantially from this paradigm. The pathogen lacks orthologs of many canonical envelope response proteins and instead relies on a single two-protein regulatory system to globally modulate every layer of the envelope and control both antibiotic resistance and ability to cause disease. This unique system, known as BfmRS, lowers susceptibility to a wide range of drugs, antagonizes innate immune killing, and facilitates development of lethal disease in mice. Intriguingly, a clinical isolate showing enhanced virulence requires the system for growth. BfmRS is therefore tightly linked to the intractability of infections with the pathogen and represents a key potential therapeutic target. Despite its fundamental importance, we lack an understanding of how the large BfmRS regulon controls broad- range drug resistance and pathogenicity, and what signals the system senses. The objective of the proposed studies is to understand how A. baumannii uses a single control circuit to simultaneously modulate resistance and virulence. Our central hypothesis is that BfmRS jointly controls the barrier to both drug penetration and innate immune attack by modulating the level of key outer membrane (OM) structures in response to disruptions in envelope protein production. We will test this hypothesis by pursuing three Aims, which build on our extensive preliminary data defining the BfmRS regulon and its chemical-genetic profile, as well as the phosphorylation cascade it uses for signaling. In Aim 1 we will test the model that BfmRS controls the bacterial interface with both antibiotics and innate immune effectors by modulating the OM barrier. In Aim 2, we will identify the antibiotic-induced and intrinsic stress signals that are sensed by BfmRS. In Aim 3, we will define the relationship between variability in BfmRS activity, growth-dependence, and virulence across diverse patient isolates as a test of the model that variation in BfmRS signaling level is a driver of enhanced virulence in invasive strains. This work will elucidate the mechanisms by which a unique regulatory system controls both resistance and pathogenicity in a critically important nosocomial microbe. These results will inform strategies for potentiating antibiotic and immune action for killing extensively drug-resistant bacteria.