Disruption in bacterial cell envelope following polymyxin challenge and adaptations in tolerant strains

多粘菌素攻击后细菌细胞包膜的破坏和耐受菌株的适应

• 批准号: BB/X002446/1
• 负责人: Boyan Bonev
• 金额: $ 43.32万
• 依托单位: University of Nottingham
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2023
• 资助国家: 英国
• 起止时间: 2023 至 无数据
• 项目状态: 未结题
• 来源: https://gtr.ukri.org/projects?ref=BB%2FX002446%2F1
• 关键词: Disruption; bacterial; cell; envelope; following

Bacterial infections remain a major challenge to healthcare and the problem is exacerbated by the development or acquisition of resistance to antibiotics. The group of Gram-negative bacteria are particularly refractive to management, as the structure of their cell envelope includes an outer membrane that confers natural protection from antibiotics and antimicrobials. For example, the molecular targets for the most widely used antibiotics from the penicillin group, are protected within the bacterial outer membrane. Also protected is the inner bacterial membrane, which plays a defining role in maintaining the living state of cells. Both membranes have a continuous bilayer structure with distinctly different architecture and composition.Polymyxins are one class of antimicrobial compounds with activity against Gram-negative bacteria that have found restricted clinical use as last line therapeutics. They show comparatively high toxicity and despite a wealth of research and history of clinical use, their mechanism of action remains poorly understood. During their action, polymyxins utilise and subvert a bacterial surface receptor, lipopolysaccharide, to cross the protective outer membrane and access the inner membrane, where they exercise their killing action. In this proposal, we aim to decipher the molecular details of bacterial killing by polymyxins, describe the stages of polymyxin-induced bacterial death, and investigate the detailed structural and molecular changes in bacterial outer and inner membranes that result from adaptive changes in resistant bacteria. We seek a molecular template from the interaction between polymyxin and its target, lipopolysaccharide, from resistant bacteria, which will inform engineering of polymyxin antimicrobials with enhanced activity against resistant Gram-negative pathogens.To achieve this, we combine advanced force microscopy that can map bacterial surfaces at molecular resolution, with magnetic resonance spectroscopy providing molecular and structural information at atomic level of detail, to investigate the interaction of polymyxins with bacterial outer and inner membranes, the changes in their structure, organisation and stability. we hypothesise initial outer membrane breach by polymyxin disrupts the normal exchange of molecular material between the two membranes and dysregulates organisation of both outer and inner membranes. To investigate the lethal consequences of this dysregulation, we will monitor bacterial viability and will use electron microscopy to monitor the sequential collapse of important structural elements in the bacterial envelope. Finally, we will employ this methodology to reveal what changes in bacterial membrane structure and molecular architecture confer protection against polymyxins in resistant bacteria.

细菌感染仍然是医疗保健的主要挑战，并且由于对抗生素的耐药性的发展或获得而加剧了该问题。革兰氏阴性菌群对管理特别敏感，因为它们的细胞被膜结构包括一层外膜，可以提供天然保护，免受抗生素和抗菌剂的侵害。例如，最广泛使用的青霉素类抗生素的分子靶标在细菌外膜内受到保护。细菌内膜也受到保护，它在维持细胞的生存状态方面起着决定性的作用。这两种膜都具有连续的双层结构，具有明显不同的结构和组成。多粘菌素是一类对革兰氏阴性菌具有活性的抗微生物化合物，已发现其作为最后一线治疗剂的临床用途受到限制。它们显示出相对高的毒性，尽管有大量的研究和临床使用历史，但它们的作用机制仍然知之甚少。在它们的作用过程中，多粘菌素利用并破坏细菌表面受体脂多糖，以穿过保护性外膜并进入内膜，在那里它们发挥它们的杀伤作用。在这个提议中，我们的目标是破译多粘菌素杀死细菌的分子细节，描述多粘菌素诱导的细菌死亡的阶段，并研究细菌外膜和内膜的详细结构和分子变化，这些变化是由耐药细菌的适应性变化引起的。我们从多粘菌素与耐药细菌的靶标脂多糖之间的相互作用中寻找分子模板，这将为多粘菌素抗菌剂的工程设计提供信息，这些抗菌剂对耐药革兰氏阴性病原体具有增强的活性。为了实现这一目标，我们将联合收割机先进的力显微镜与磁共振光谱相结合，力显微镜可以在分子分辨率下绘制细菌表面，磁共振光谱可以在原子水平上提供分子和结构信息，研究多粘菌素与细菌外膜和内膜的相互作用及其结构、组织和稳定性的变化。我们假设多粘菌素最初的外膜破裂破坏了两个膜之间分子物质的正常交换，并使外膜和内膜的组织失调。为了研究这种失调的致命后果，我们将监测细菌的活力，并将使用电子显微镜来监测细菌包膜中重要结构元件的连续崩溃。最后，我们将采用这种方法来揭示细菌膜结构和分子结构的变化赋予耐药细菌对多粘菌素的保护作用。