Identifying host human products responsible for natural transformation of resistance traits in Acinetobacter spp

项目概要/摘要 近年来，抗生素耐药细菌的出现大量增加， 在临床环境中观察到。鲍曼不动杆菌是最广泛的病原体之一， 导致这些令人担忧的感染。这种细菌的特点是基因组的可塑性极强， 水平遗传转移（horizontal genetic transfer，HGT）这些特点是A. 鲍曼不动杆菌获得抗药性基因的非凡能力。尽管外国的相关性 DNA的获得与A. baumannii，努力阐明 自然的转变是很少的。我们最近证明，人类的存在 细胞外宿主液中的血清白蛋白（HSA）与A.鲍曼尼天然 转型我们还观察到A.鲍氏转录 调节因子H-NS响应于HSA而下降，并且能力相关基因表达增加 在H-NS突变株中。这一观察结果表明，细胞的H-NS水平的变化可能发挥作用， 在自然转化中的重要作用。因此，我们假设HSA与细菌的相互作用 表面组分触发降低H-NS表达的调节信号级联， 导致参与天然感受态的基因的表达增强。为了验证这个假设，我们 将研究HSA与A.鲍曼不动杆菌细胞表面蛋白使用受体活性- 定向亲和标记（重标记）技术（AIM 1）。为了更好地理解 响应级联负责HSA介导的转化效率的增加，我们将 使用互补RNA-seq确定与感受态相关的H-NS调节基因， 野生型或h-ns突变体中的ChIP-seq分析（目的2）。本申请中提出的研究将 揭示宿主适应过程导致这种具有挑战性的病原体的抗生素耐药性， 在全球范围内越来越重要。我们将提供新的见解细菌成分作用于 H-NS在HSA介导的转录反应中的作用， DNA摄取量的增加。未来的研究可以利用这些发现来开发新的 治疗严重不动杆菌人类感染的方法，特别是由新出现的 多重耐药菌株

Project summary/Abstract In recent years, a massive increase in the emergence of antibiotic resistant bacteria has been observed in clinical settings. Acinetobacter baumannii is one of the most widespread pathogens that cause these alarming infections. This bacterium is characterized by its extreme genome plasticity, facilitated by horizontal genetic transfer (HGT) processes. These characteristics are the cause of A. baumannii's remarkable ability to acquire antibiotic-resistance genes. Despite the relevance of foreign DNA acquisition to the pathobiology of A. baumannii, efforts to elucidate the mechanism/s involved in natural transformation have been scarce. We have recently demonstrated that the presence of human serum albumin (HSA) in extracellular host fluids correlates with an increase in A. baumannii natural transformation. We have also observed that the expression of the A. baumannii transcriptional regulator H-NS drops in response to HSA and that competence-associated gene expression increases in the h-ns mutant strains. This observation suggests that changes in cell's H-NS levels may play a central role in natural transformation. Hence, we hypothesize that the interaction of HSA with bacterial surface components triggers a regulatory signaling cascade that decreases H-NS expression, resulting in enhanced expression of genes involved in natural competence. To test this hypothesis, we will examine the interaction of HSA with A. baumannii cell surface proteins using the receptor activity- directed affinity tagging (re-tagging) technique (aim 1). To better understand the transcriptional response cascade responsible for HSA-mediated increase in transformation efficiency, we will determine the H-NS regulated genes associated with competence using complementary RNA-seq and ChIP-seq analyses in wild-type or h-ns mutants (aim 2). The studies proposed in this application will shed light on host adaptation processes leading to antibiotic resistance in this challenging pathogen of increasing relevance worldwide. We will provide new insights into bacterial components acting at the top of the HSA signaling cascade and H-NS's role in HSA-mediated transcriptional responses, leading to an increase in DNA-uptake. Future studies can then use these findings to develop novel approaches to treat severe Acinetobacter human infections, particularly those caused by emerging multidrug-resistant isolates.