Global Circuitry that Controls Acinetobacter Resistance and Virulence

项目摘要 鲍曼不动杆菌是已知的最耐抗生素的病原体之一， 具有增强的毒力的分离物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细胞包膜阻止抗生素和免疫攻击是至关重要的， 制定新的战略来控制这一威胁。细菌中包膜的合成和完整性 通常由控制包络的特定方面的大量响应系统来维持。A. 然而，鲍曼尼与这一范式有很大不同。这种病原体缺乏许多 典型的包膜反应蛋白，而是依赖于一个单一的双蛋白调节系统， 全面调节包膜的每一层，控制抗生素耐药性和 导致疾病。这种独特的系统，被称为BfmRS，降低了对各种药物的敏感性， 拮抗先天性免疫杀伤，并促进小鼠致死性疾病的发展。有趣的是，A 显示增强的毒力的临床分离株需要用于生长的系统。因此，BfmRS与 与病原体感染的难治性有关，并且代表了关键的潜在治疗靶点。尽管 其根本的重要性，我们缺乏了解如何大BfmRS调节子控制广泛的- 范围耐药性和致病性，以及系统感知到的信号。的目的 研究目的是了解A.鲍曼尼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共同控制对两者的屏障， 通过调节关键外膜（OM）结构的水平， 以响应包膜蛋白生产的中断。我们将通过以下三个方面来检验这一假设： 目的，这是建立在我们广泛的初步数据，定义BfmRS调节子及其化学遗传学 以及它用于信号传导的磷酸化级联反应。在目标1中，我们将测试模型， BfmRS通过调节细菌与抗生素和先天免疫效应子的相互作用来控制细菌与抗生素和先天免疫效应子的相互作用。 OM屏障。在目标2中，我们将识别通过以下方式感测到的应力诱导和内在应力信号： BfmRS。在目标3中，我们将定义BfmRS活性的变异性、生长依赖性 作为BfmRS信号传导水平的变化是 是入侵菌株毒力增强的驱动因素。这项工作将阐明的机制， 独特的调节系统控制着一个至关重要的医院感染中的耐药性和致病性。 微生物这些结果将为加强抗生素和免疫作用的策略提供信息， 广泛耐药细菌。

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.