Defining the systems-level impact of iron limitation in Klebsiella pneumoniae

我的研究计划的长期目标是了解允许细菌适应营养限制的基本机制。铁是许多细胞过程的重要组成部分，包括DNA复制和氧代谢，以及许多细胞反应的辅助因子。在肺炎克雷伯氏菌，革兰氏阴性，包囊细菌，铁的作用及其对铁载体表达的影响，最近在转录水平上进行了研究，确定了在炎症，细菌传播，和缺氧诱导因子1a稳定感染过程中的作用。然而，在蛋白质水平上，可变铁浓度的影响尚未得到很好的定义。最近，我们发现铁可利用性的变化影响K.肺炎。我们对铁在K.肺炎链球菌发现了多种蛋白质的调节，包括与信号转导途径相关的蛋白质（例如，cAMP受体和激酶），细菌细胞粘附（例如，脂蛋白），多糖胶囊产生（例如，胶囊输出蛋白），酶活性（例如，蛋白酶），和稳态（例如，转录因子）。此外，蛋白质的破坏（例如，铁蛋白酶（Ion protease）受铁存在或不存在的影响调节细菌生长、荚膜和铁利用。我们的工作已经开始揭示铁对K.虽然铁在肺炎杆菌中的作用是重要的，但关于铁直接（通过转运蛋白或铁载体）或间接（通过转录调节因子、信号级联）影响细菌存活的机制仍存在许多问题。最重要的假设是K。肺炎杆菌改变其蛋白质组以响应改变的铁浓度来调节多种细胞过程以促进其存活。对于这一建议，我将集中在铁的可用性之间的联系，在K。pneumoniae和i）信号转导途径，ii）酶产生，和iii）一般应激反应的调节。在接下来的5年里，我的研究计划将为铁在K.肺炎和定义强调细菌适应性的生物学机制。这项工作对我们理解细菌对铁的反应具有重要意义，我们的发现，沿着使用的方法，将超越原核细胞生物学，适用于不同的生物系统（例如，真菌物种）。

The long-term goal of my research program is to understand fundamental mechanisms that allow bacteria to adapt to nutrient limitation. Iron is a critical component of many cellular processes, including DNA replication and oxygen metabolism, as well as a cofactor for many cellular reactions. In Klebsiella pneumoniae, a Gram--negative, encapsulated bacterium, the role of iron and its influence on siderophore expression was recently studied at the transcriptional level, defining a role in inflammation, bacterial dissemination, and hypoxia -inducible factor 1a stabilization during infection. However, at the protein level, the effect of variable iron concentrations has not been well defined. Recently, we discovered that changes in iron availability impact the cellular proteome and secretome of K. pneumoniae. Our proteomic investigation into the role of iron in K. pneumoniae uncovered modulation of a variety of proteins, including those associated with signal transduction pathways (e.g., cAMP receptor and kinases), bacterial cell adhesion (e.g., lipoproteins), polysaccharide capsule production (e.g, capsule export protein), enzymatic activity (e.g., proteases), and homeostasis (e.g., transcription factors). Moreover, disruption of proteins (e.g., Lon protease) influenced by the presence or absence of iron modulate bacterial growth, capsule, and iron utilization. Our work has begun to uncover the diverse impact of iron on cellular processes and regulation in K. pneumoniae, but many questions remain regarding the mechanisms by which iron directly (via transporters or siderophores) or indirectly (via transcriptional regulators, signaling cascades) influences bacterial survival. The overarching hypothesis is that K. pneumoniae alters its proteome in response to changing iron concentrations to modulate a diverse array of cellular processes to promote its survival. For this proposal, I will focus on the connection between iron availability in K. pneumoniae and the regulation of i) signal transduction pathways, ii) enzyme production, and iii) general stress response. Over the next 5 years, my research program will provide novel insight into the diverse role of iron in K. pneumoniae and define the biological mechanisms that underscore bacterial adaptability. This work has important implications for our understanding of the bacterial response to iron, and our findings, along with the approaches used, will transcend prokaryotic cell biology and be applicable to diverse biological systems (e.g., fungal species).