Phenylacetic acid catabolism, a novel stress-response pathway in Acinetobacter baumannii

苯乙酸分解代谢，鲍曼不动杆菌中一种新的应激反应途径

• 批准号: 10621274
• 负责人: Mario Feldman
• 金额: $ 67.11万
• 依托单位: WASHINGTON UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2022
• 资助国家: 美国
• 起止时间: 2022-05-12 至 2027-04-30
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10621274
• 关键词: Acinetobacter; Acinetobacter Infections; Acinetobacter baumannii; Acute; Adherence; Affect; Anabolism; Antibiotic Therapy; Antibiotic susceptibility; Antibiotics; Auxins; Biological Assay; Biological Process; Catabolism; Categories; Cell physiology; Cells; Centers for Disease Control and Prevention (U.S.); Clinical; Clinical Research; Collaborations; Cytoplasm; Disease; Environment; Enzymes; Epithelial Cells; Exposure to; Extracellular Matrix Proteins; Foundations; Future; Gene Expression; Genes; Genetic; Genetic Transcription; High Pressure Liquid Chromatography; Hospitals; Hydrogen Peroxide; Hypoxia; Infection; Iron; Lead; Life; Lung infections; Measures; Mediating; Microbial Biofilms; Modeling; Molecular; Multi-Drug Resistance; Multidrug-resistant Acinetobacter; Mus; Mutagenesis; Mutate; Mutation; Operon; Osmosis; Oxidative Stress; Pathogenesis; Pathway interactions; Phagocytes; Phenotype; Phenylalanine; Physiological; Pilum; Plants; Process; Production; Property; Regulation; Reporter; Repression; Research Priority; Role; Second Messenger Systems; Signal Pathway; Signal Transduction; Signaling Molecule; Stress; Sulfamethoxazole; System; Testing; Therapeutic; Trimethoprim; Urinary tract infection; Virulence; Work; World Health Organization; antibiotic tolerance; antimicrobial; biological adaptation to stress; catheter associated UTI; clinically relevant; combat; gene repression; genetic regulatory protein; mouse model; mutant; novel; novel therapeutic intervention; pathogen; pathogenic bacteria; phenylacetic acid; pressure; prevent; research and development; resistance mechanism; response; stress tolerance; stressor; therapy outcome; transcriptomics

PROJECT SUMMARY/ABSTRACT Multidrug resistant (MDR) infections caused by the bacterial pathogen Acinetobacter baumannii are increasing at alarming rates. Currently, over 60 % of global A. baumannii clinical isolates are MDR, leading the Centers for Disease Control and Prevention and the World Health Organization to categorize it as a top priority for the research and development of new antimicrobial therapies. In addition to accumulating resistance mechanisms, A. baumannii strains develop tolerance to antibiotics, which can frequently lead to poor therapeutic outcomes even with antibiotic susceptible strains. However, the mechanisms used by A. baumannii to adapt to and tolerate hostile conditions remain largely unknown. We found that A. baumannii employs a novel stress response pathway in which phenylacetic acid (PAA), a metabolite derived from phenylalanine catabolism, acts as a signaling molecule. We established that, in the presence of sub-inhibitory concentrations of different antibiotics, such as trimethoprim/sulfamethoxazole, A. baumannii dramatically increases the transcription of the paa operon which encodes enzymes required to degrade PAA. Conversely, other conditions, like hydrogen peroxide treatment, lead to a repression of the paa operon. The regulation of the paa operon triggers a physiological adaptive response that includes the modulation of pili biosynthesis and biofilm formation. Importantly, we found that artificial augmentation of PAA levels, through the addition of commercially available PAA-derivatives or mutations in PAA degradative genes, disrupts this response Furthermore, mutating initial steps of PAA degradation leads to increased sensitivity to antibiotics and oxidative stress in multiple strains. Here we propose to use our expertise in A. baumannii genetics and pathogenesis to investigate the PAA-mediated stress response in Acinetobacter and determine its importance in virulence. We will determine the breadth of PAA signaling using reporter assays, and we will explore PAA-mediated changes in cell physiology by profiling gene expression under different stress conditions. Further, we will characterize the PAA-dependent mechanisms of cell signaling under stress by measuring cellular levels of PAA and determining the role of important regulatory proteins in this cascade. Finally, we will test the virulence of strains unable to regulate PAA levels in the catheter-associated urinary tract infection and lung infection murine models. Our work will establish the role of PAA as a key regulatory molecule in A. baumannii, determine the biological processes regulated by PAA, and uncover the mechanisms by which PAA triggers adaptations to promote survival under stress. Understanding the fundamental aspects of the PAA stress response will provide a foundation to future clinical studies.

项目概要/摘要 由细菌病原体鲍曼不动杆菌引起的多重耐药 (MDR) 感染正在增加 以惊人的速度。目前，全球超过 60% 的鲍曼不动杆菌临床分离株具有 MDR，领先于研究中心 疾病预防控制中心和世界卫生组织将其列为首要任务 新抗菌疗法的研究和开发。除了积累阻力机制外， 鲍曼不动杆菌菌株对抗生素产生耐受性，这通常会导致治疗结果不佳 即使是抗生素敏感菌株。然而，鲍曼不动杆菌用于适应和耐受的机制 敌对条件仍然很大程度上未知。我们发现鲍曼不动杆菌采用一种新颖的应激反应 苯乙酸 (PAA)（一种源自苯丙氨酸分解代谢的代谢物）在该途径中充当 信号分子。我们确定，在不同抗生素的亚抑制浓度存在下， 例如甲氧苄氨嘧啶/磺胺甲恶唑、鲍曼不动杆菌可显着增加 paa 操纵子的转录 它编码降解 PAA 所需的酶。相反，其他条件，如过氧化氢 治疗，导致paa操纵子的抑制。 Paa 操纵子的调节触发生理 适应性反应，包括调节菌毛生物合成和生物膜形成。重要的是，我们发现 通过添加市售的 PAA 衍生物或 PAA 降解基因的突变会破坏这种反应此外，突变 PAA 的初始步骤 降解导致多种菌株对抗生素和氧化应激的敏感性增加。在这里我们建议 利用我们在鲍曼不动杆菌遗传学和发病机制方面的专业知识来研究 PAA 介导的应激反应 不动杆菌中并确定其毒力的重要性。我们将使用以下方法确定 PAA 信号传导的广度 报告基因检测，我们将通过分析基因表达来探索 PAA 介导的细胞生理学变化 在不同的应力条件下。此外，我们将描述 PAA 依赖性细胞信号传导机制 通过测量 PAA 的细胞水平并确定重要调节蛋白在压力下的作用 级联。最后，我们将测试无法调节导管相关PAA水平的菌株的毒力。 尿路感染和肺部感染小鼠模型。我们的工作将确立 PAA 的关键作用 鲍曼不动杆菌中的调节分子，确定 PAA 调节的生物过程，并揭示 PAA 触发适应以促进压力下生存的机制。了解 PAA 应激反应的基本方面将为未来的临床研究奠定基础。