Environmental regulation of bacterial growth and cell division

项目摘要 环境是细菌生长和行为的主要决定因素。它不仅影响新陈代谢和 生长速度，还包括形态、发育和对抗生素的敏感性。我们的研究中心集中在 与环境协调细胞生长和细胞周期进程的基本过程。在细菌中 这些过程是关键的，在广泛的物理化学环境中最大限度地发挥了扩散潜力。 这些过程中的缺陷可能是灾难性的，会损害生长，降低活性，并呈现细胞 对抗菌剂过敏。抗生素耐药性病原体的日益流行提供了一种 对我们的工作有强大的动力。了解细菌如何适应物理化学环境 应揭示治疗细菌病原体的新方法，并确定 下一代疗法的发展。在这一努力中，我们使用了进化上截然不同的有机体 包括两种革兰氏阴性革兰氏蛋白杆菌：模式生物大肠杆菌和病原菌 肺炎克雷伯菌。2019年，肺炎克雷伯菌是全球第三大死亡原因，原因是或 与抗生素耐药性有关(《柳叶刀》，2022)。 细胞膜对细菌的生存至关重要，既是渗透屏障，又是支柱。 顶住充气压力。暴露在环境中，基本的细胞包膜过程必须保持正常运行 在大范围的条件下。了解构成和保持细胞包膜完整性的因素 是一个主要的研究重点。扩大我们的发现，在大肠杆菌细胞壁之间存在功能冗余 酶可确保跨越pH值的强劲生长，我们将使用单分子技术和生物化学来 说明pH对单个PBP转肽酶活性的影响。这些酶起着一种 在肽聚糖交联中起关键作用，是β-内酰胺类抗生素的靶标。我们还将确定 PH介导的细胞壁合酶活性和β-内酰胺抗性变化的因素 肺炎。作为了解协调细胞包膜生物发生的机制的更广泛努力的一部分 随着细胞的生长和细胞周期的进展，我们将阐明外膜的基本作用 大肠杆菌生物学中的脂多糖(LPS)组分。最后，在我们对 营养可利用性与细胞形态之间的关系，我们将描述 一种新发现的饥饿介导的应激反应，细胞质凝聚，并确定其效应因子(S) 负责饥饿相关的警报蛋白ppGpp与细胞分裂之间的正相关关系。 我们在这些努力中得到了我们的多学科方法的帮助，这种方法采用了各种不同的 技术，以及由亲密的同事和合作者组成的广泛网络，我们与他们一起享受免费的 试剂和思想的交流。这些优势使我们能够回答以前难以回答的问题 在整个生命树中与有机体相关的生理学和动态平衡控制。

Project Summary The environment is a primary determinant of bacterial growth and behavior. It impacts not only metabolism and growth rate, but also morphology, development, and antibiotic susceptibility. Our research centers on the essential processes that coordinate cell growth and cell cycle progression with the environment. In bacteria these processes are critical, maximizing proliferative potential across a wide physicochemical landscape. Defects in these processes can be catastrophic, impairing growth, reducing viability, and rendering cells hypersensitive to antimicrobials. The increasing prevalence of antibiotic resistant pathogens provides a powerful motivation for our work. Understanding how bacteria adapt to the physicochemical environment should reveal novel approaches for the treatment of bacterial pathogens and identify targets for the development of next-generation therapeutics. In this this effort we employ evolutionarily distinct organisms including two Gram-negative Gammaproteobacteria: the model organism Escherichia coli and the pathogen Klebsiella pneumoniae. In 2019 K. pneumoniae was the third leading cause of global deaths due to or associated with antibiotic resistance (Lancet, 2022). The cell envelope is vital to bacterial viability, required as both a permeability barrier and a buttress against turgor pressure. Exposed to the environment, essential cell envelope processes must remain functional across a large range of conditions. Understanding the factors that underlie and preserve cell envelope integrity is a primary research focus. Extending our finding that functional redundancy amongst E. coli cell wall enzymes ensures robust growth across pH values, we will use single molecule techniques and biochemistry to illuminate the impact of pH on the activity of individual PBP transpeptidases in situ. These enzymes play a critical role in peptidoglycan cross linking and are the target of beta-lactam antibiotics. We will also identify factors underlying pH-mediated changes in cell wall synthase activity and beta-lactam resistance in K. pneumoniae. As part of a broader effort to understand the mechanisms coordinating cell envelope biogenesis with cell growth and cell cycle progression, we will elucidate the essential role of the outer membrane component lipopolysaccharide (LPS) in E. coli biology. Finally, building on our longstanding interest in the relationship between nutrient availability and cell morphology, we will characterize the mechanisms governing a newly identified starvation-mediated stress response, cytoplasmic condensation, and identify the effector(s) responsible for the positive relationship between the starvation-associated alarmone, ppGpp, and cell division. We are aided in these endeavors by our multidisciplinary approach that employs a diverse array of techniques, as well as an extensive network of close colleagues and collaborators with whom we enjoy a free exchange of reagents and ideas. These advantages allow us to answer previously intractable questions in physiology and homeostatic control that are relevant to organisms throughout the tree of life.