Mechanisms for antibiotic tolerance and envelope remodeling in Gram-negative bacteria

不列颠哥伦比亚大学的Elitza Tocheva和康奈尔大学的Tobias Dörr之间的这项合作旨在阐明细菌包膜形态形成和抗生素耐受性的机制，同时为他们的研究团队提供高质量的培训。处于这项研究中心的各种革兰氏阴性细菌显示出强大的生存能力，能够在灾难性的包膜损伤和细胞壁丧失的情况下生存下来。这些细菌可以弥补细胞壁的不足，直到破坏因素，即作用于细胞壁的抗生素，如青霉素被移除，它们可以再生自己的细胞壁。这种现象被称为“抗生素耐受”。由于细菌细胞壁是几类抗生素的靶标，因此我们必须了解允许这些耐受细菌在细胞壁靶向抗生素中存活的机制。观察这些耐受细菌从细胞壁缺陷状态恢复到有壁状态的过程，也为解决难以捉摸的但根本的问题提供了机会，即杆状细菌如何在没有预先存在的细胞壁模板的情况下建立其细胞形状。Tocheva和Dörr团队将应用先进的高分辨率冷冻电子断层扫描、遗传学和生物化学的独特而强大的组合来解决这些未被研究和历史上困难的研究问题。Dörr实验室在霍乱弧菌、阴沟肠杆菌和肺炎克雷伯菌中进行的基因筛查已经确定了关键的细菌应激反应系统和包膜生物发生途径，这些途径有助于产生抗生素耐药性。这些研究是关于革兰氏阴性细菌被膜每一层在细胞壁降解和再生过程中所起作用的许多假说的来源，Tocheva实验室将通过冷冻电子断层扫描和相关的荧光显微镜技术来探索这些假说。这个由学员推动的项目将在基础细菌学和新兴的抗生素耐药性领域建立加拿大的专业知识。

This collaboration between Elitza Tocheva at the University of British Columbia and Tobias Dörr at Cornell University seeks to elucidate mechanisms of bacterial envelope morphogenesis and antibiotic tolerance while providing quality training to their research teams. The diverse Gram-negative bacteria at the center of this research display a robust ability to survive catastrophic envelope damage and the loss of their cell walls. These bacteria can compensate for cell wall deficiency until the damaging agent, i.e., a cell wall-acting antibiotic like penicillin, is removed and they can regenerate their cell walls. This phenomenon is termed "antibiotic tolerance." As the bacterial cell wall is the target of several classes of antibiotics, it is critical that we understand the mechanisms that permit these tolerant bacteria to survive cell wall-targeting antibiotics. Observing the recovery of these tolerant bacteria from a cell wall-deficient state back to a walled state also presents an opportunity to tackle the elusive yet fundamental question of how rod-shaped bacteria establish their cell shape without the template of a pre-existing cell wall. The Tocheva and Dörr groups will apply a unique and powerful combination of advanced, high-resolution cryo-electron tomography, genetics, and biochemistry to these understudied and historically difficult research questions. Genetic screens performed by the Dörr lab in V. cholerae, E. cloacae, and K. pneumoniae have identified key bacterial stress response systems and envelope biogenesis pathways that contribute to antibiotic tolerance. These studies are the source of numerous hypotheses regarding the roles of each layer in the Gram-negative bacterial envelope during cell wall degradation and regeneration that will be probed by the Tocheva lab via cryo-electron tomography and correlative fluorescent microscopy techniques. This trainee-driven project will establish Canadian expertise in both fundamental bacteriology and the emerging field of antibiotic tolerance.