INVESTIGATING TYPE VI SECRETION IN ACINETOBACTER BAUMANNII AND ITS INTERPLAY WITH ANTIBIOTIC RESISTA

研究鲍曼不动杆菌 VI 型分泌物及其与抗生素耐药性的相互作用

• 批准号: 9156408
• 负责人: Mario Feldman
• 金额: $ 38.13万
• 依托单位: WASHINGTON UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-06-22 至 2021-05-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9156408
• 关键词: Acinetobacter Infections; Acinetobacter baumannii; Affect; Amino Acids; Anti-Bacterial Agents; Antibiotic Resistance; Antibiotics; Bacteria; Biogenesis; Biological; Biological Assay; Catabolism; Cell Differentiation process; Cells; Chemotactic Factors; Communicable Diseases; Coupled; Data; Development; Eukaryota; Frequencies; Genes; Goals; Gram-Negative Bacteria; Health; Healthcare Systems; Human; Immunity; Infection; Injection of therapeutic agent; Intoxication; Investigation; Killer Cells; Knowledge; Lead; Mediating; Metabolic; Metabolic Pathway; Mission; Modeling; Modification; Multi-Drug Resistance; Multidrug-resistant Acinetobacter; Mutagenesis; Nosocomial Infections; Organism; Outcome; Pathway interactions; Peptidoglycan; Phenotype; Physiological; Physiological Adaptation; Pilum; Plants; Plasmids; Population; Process; Production; Prokaryotic Cells; Proteins; Proteomics; Recruitment Activity; Regulation; Research; Resistance; Role; Signaling Molecule; Superbug; System; Testing; Time; United States National Institutes of Health; Work; abstracting; antimicrobial; base; cell motility; clinically relevant; combat; comparative; cost; driving force; fitness; in vivo; insight; killings; novel; novel strategies; pathogen; phenylacetic acid; prevent; research study; resistant strain; transcriptome sequencing; transcriptomics; weapons

PROJECT SUMMARY/ABSTRACT Multidrug resistant (MDR) Acinetobacter baumannii has emerged as a frequent cause of nosocomial infections with some isolates resistant to all clinically relevant antibiotics. We have previously identified a type VI secretion system (T6SS) in this organism. The multi-component T6SS apparatus facilitates a dynamic contact-dependent injection of toxic effector proteins into competing bacteria. The T6SS is energetically costly, and therefore in most bacteria appears to be exquisitely regulated. We recently showed that several MDR A. baumannii isolates harbor a large, self-transmissible resistance plasmid that negatively regulates T6SS. We found that T6SS is silenced in plasmid-containing, antibiotic-resistant cells, while part of the population undergoes frequent plasmid loss and activation of the T6SS. This activation results in T6SS- mediated killing of competing bacteria but renders A. baumannii susceptible to antibiotics. We propose that differentiation of A. baumannii cells into bacterial killers involves multiple phenotypic and metabolic changes and that the fitness costs associated with the MDR and T6SS phenotypes are the driving forces for this differentiation. RNAseq and differential quantitative proteomics experiments revealed that unexpected metabolic pathways related to amino acid catabolism were plasmid-regulated. Most of these metabolic changes seem to be consequence of energetic adaptations to T6SS activation and carriage of a MDR plasmid. By mutagenesis and comparative fitness assays we will determine the importance of these metabolic changes. Interfering with these pathways may result in novel strategies to combat A. baumannii infections. We will investigate how T6SS is regulated in MDR strains that do not carry plasmids to extend our conclusions to these strains. The mechanisms by which the T6SS apparatus crosses the peptidoglycan layer of the killer cell has not been determined in any bacteria. We will define the role of a putative peptidoglycanase in this process. We have also discovered phenotypic adaptations related to plasmid loss, involving piliation and motility. The biological significance of these changes will be assessed. RNAseq data led us to the hypothesis that a metabolic intermediate, phenylacetic acid (PAA), is employed as chemoattractant to recruit prey and increase the killing efficiency. Determining the role of PAA in T6SS mediated killing may result in a new paradigm for T6SS-mediated killing with important ecological implications. The outcome of this work will be a detailed understanding of the interplay between the T6SS and the MDR phenotype and the physiological changes associated to this activation, which may lead to the development of new strategies to treat Acinetobacter infections.

项目总结/摘要 多药耐药（MDR）鲍曼不动杆菌已成为引起 医院感染，一些分离株对所有临床相关抗生素耐药。我们有 先前在该生物体中鉴定了VI型分泌系统（T6 SS）。多组分 T6 SS装置促进了毒性效应蛋白的动态接触依赖性注射， 竞争细菌T6 SS在能量上是昂贵的，因此在大多数细菌中， 要严格控制。我们最近发现几种MDR A.鲍曼不动杆菌分离株 一种能负调控T6 SS的大的、可自我传递的抗性质粒。我们发现T6 SS 在含有质粒的抗肿瘤细胞中沉默，而部分群体 经历频繁的质粒丢失和T6 SS的激活。这种激活导致T6 SS- 介导的竞争细菌的杀死，但使A.鲍曼不动杆菌对抗生素敏感。我们 提出了A.将鲍曼不动杆菌转化为细菌杀手涉及多个 表型和代谢变化，以及与MDR相关的适应性成本， T6 SS表型是这种分化的驱动力。RNAseq和差异 定量蛋白质组学实验显示，与 氨基酸催化剂是质粒调控的。大多数代谢变化似乎是 这是对T6 SS活化和携带MDR质粒的能量适应的结果。通过 诱变和比较适合性测定，我们将确定这些的重要性， 代谢变化干扰这些途径可能会导致新的战略，以打击A。 鲍曼不动杆菌感染。我们将研究T6 SS在MDR菌株中是如何调节的， 将我们的结论扩展到这些菌株。T6 SS的机制 装置穿过杀伤细胞的肽聚糖层尚未确定在任何 细菌我们将确定一个假定的肽聚糖酶在这一过程中的作用。我们还 发现了与质粒丢失相关的表型适应，涉及毛化和运动性。的 将评估这些变化的生物学意义。RNAseq数据让我们得出了一个假设， 代谢中间体苯乙酸（PAA）被用作化学引诱物， 招募猎物，提高猎杀效率。确定PAA在T6 SS介导的细胞凋亡中的作用 杀死可能导致T6 SS介导的杀死的新范例， 影响这项工作的结果将是详细了解之间的相互作用， T6 SS和MDR表型以及与该活化相关的生理变化， 这可能导致治疗不动杆菌感染的新策略的发展。