Bioorganic chemistry of polybasic amphiphiles (PAs): Disarming bacterial defense mechanisms in Gram-negative bacteria (GNB)

多元两亲物 (PA) 的生物有机化学：解除革兰氏阴性菌 (GNB) 中的细菌防御机制

• 批准号: RGPIN-2018-06047
• 负责人: Schweizer, Frank
• 金额: $ 9.32万
• 依托单位: University of Manitoba
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2022
• 资助国家: 加拿大
• 起止时间: 2022-01-01 至 2023-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=748084
• 关键词: Bioorganic; chemistry; polybasic; amphiphiles; PAs

Low membrane permeability and extensive efflux are bacterial defence mechanisms which synergistically reduce compound accumulation in Gram-negative bacteria (GNB) resulting in intrinsic resistance that prevents compounds from achieving their (intended) biological effect(s). GNB possess two cellular membranes with orthogonal membrane penetrating properties. The lipopolysaccharide (LPS)-coated outer membrane (OM) is impermeable for most hydrophobic agents. Compounds that are able to traverse the OM typically do so through narrow -barrel proteins (porins) that are lined with charged amino acids. Once inside the periplasm compounds are susceptible to multidrug efflux pumps; thus, to accumulate in GNB to a level that is sufficient for activity, compounds typically must traverse porins faster than they are pumped out. The resultant orthogonal physicochemical properties combined with the overexpression of efflux pumps pose a significant challenge for traditional small molecules to overcome. In addition to porins, an alternative OM delivery pathway involves the self-promoted uptake mechanism of polybasic amphiphiles (PAs). PAs cross the OM by interacting with sites at which divalent cations crossbridge adjacent polyanionic LPS polymers. This causes a destabilization of the OM that is proposed to lead to self-promoted uptake of the PA and/or other compounds into GNB. The overall objective of the proposed research program is the design, synthesis and study of the chemical and biological properties of tailor made, multifunctional PAs and their effects on compound accumulation in GNB. GOAL 1 studies how the physicochemical properties of five PA-based scaffolds affect membrane permeability and efflux of two model compounds 1 and 2 in GNB. GOAL 2 investigates how (a) incorporation of bivalent metal chelators; (b) conjugation to a siderophore; (c) conjugation to membrane uncouplers: (d) the presence of homofunctional multivalency and (e) heterofunctional multivalency effects in PAs influence accumulation of 1 and 2 in GNB. GOAL 3 explores the effects of PA- and siderophore-based ligation on membrane permeability and efflux of 1 and 2 in GNB. The long-term goal is to develop chemical interventions to disarm bacterial defences in GNB. The proposed research is expected to make significant contributions, including potential breakthroughs in a wide variety of areas associated with biological chemistry of bacterial systems, bioorganic- and analytical chemistry and microbiology. The information gathered by these studies will have immediate, direct strong impacts on the development of chemical strategies to disarm bacterial defence mechanisms and counter antimicrobial resistance in GNB with multiple applications including food and water safety, veterinary health, agriculture and security. The outlined program will train 4 PhD, 2 MSc and 10 UG in chemical biology of bacterial systems.

低膜渗透性和广泛的外排是细菌防御机制，可协同减少革兰氏阴性菌 (GNB) 中的化合物积累，从而产生内在耐药性，阻止化合物实现其（预期）生物效应。 GNB 拥有两层具有正交膜穿透特性的细胞膜。脂多糖 (LPS) 涂层的外膜 (OM) 对于大多数疏水剂来说是不可渗透的。能够穿过 OM 的化合物通常是通过排列有带电氨基酸的窄桶蛋白（孔蛋白）来实现的。一旦进入周质化合物，就容易受到多药外排泵的影响；因此，为了在 GNB 中积累到足以发挥活性的水平，化合物通常必须比它们被泵出的速度更快地穿过孔蛋白。由此产生的正交物理化学性质与外排泵的过度表达相结合，对传统小分子提出了需要克服的重大挑战。除了孔蛋白之外，另一种 OM 传递途径涉及多元两亲物 (PA) 的自我促进摄取机制。 PA 通过与二价阳离子桥接相邻聚阴离子 LPS 聚合物的位点相互作用来穿过 OM。这会导致 OM 不稳定，进而导致 PA 和/或其他化合物自我促进进入 GNB。拟议研究计划的总体目标是设计、合成和研究定制的多功能 PA 的化学和生物特性及其对 GNB 中化合物积累的影响。目标 1 研究五种 PA 支架的理化性质如何影响 GNB 中两种模型化合物 1 和 2 的膜通透性和流出。目标 2 研究如何 (a) 掺入二价金属螯合剂； (b)与铁载体缀合； (c) 与膜解偶联剂的缀合：(d) PA 中同功能多价的存在和 (e) 异功能多价效应影响 GNB 中 1 和 2 的积累。目标 3 探讨基于 PA 和铁载体的连接对 GNB 中 1 和 2 的膜通透性以及外流的影响。 长期目标是开发化学干预措施来解除 GNB 中的细菌防御。 拟议的研究预计将做出重大贡献，包括在与细菌系统生物化学、生物有机化学和分析化学以及微生物学相关的广泛领域取得潜在突破。 这些研究收集的信息将对化学策略的制定产生直接、直接的强烈影响，以解除细菌防御机制并对抗 GNB 中的抗菌素耐药性，并具有多种应用，包括食品和水安全、兽医健康、农业和安全。该计划将在细菌系统化学生物学领域培养 4 名博士、2 名硕士和 10 名本科生。