Targeted development and selective delivery of small molecule antibiotics for the treatment of multidrug resistant Pseudomonas aeruginosa infections

项目总结 耐多药(MDR)细菌感染的数量继续上升，特别是由 革兰氏阴性病原体，加上过去30年来FDA批准的新抗生素的匮乏 已经导致了一种可怕的情况，如果目前的趋势继续下去，可能会导致全世界每年数百万人死亡。 耐多药铜绿假单胞菌(PA)是引起医院感染的主要原因之一 由于缺乏可行的治疗方案，该病毒已被美国疾病控制与预防中心列为“严重威胁”。 治疗MDRPA感染时必须克服的两个障碍是对当前广泛传播的耐药性 作用机制相似且抗生素在细胞内积聚较少的处方抗生素 至其额外的外膜(OM)和混杂外排泵。因此，以抗生素为目标的 MDRPA中未探索的细胞靶点以及改善这些靶点的抗生素输送的方法必须是 发展起来的。这项工作建议首先探索ATP合成酶，这是一种所有生命所必需的蛋白质，作为一种未被探索的 通过修改已知的抗结核药物贝达奎兰来开发抗生素的目标。通过比较残留物 结核分枝杆菌与PA、贝达奎林类分子BDQ结合位点的差异 将设计能够选择性抑制PA-ATP合成酶的药物。这项工作还将使我们深入了解 三磷酸腺苷合成酶抑制在抗生素药物研发中的应用。下一步，一种可切割的佐剂-抗生素混合策略将 将被开发来克服PA中的OM渗透问题。OM由一层不对称的双层结构组成 脂多糖、孔蛋白和底物通道，严重限制小分子进入细胞 尺寸和装药量。最近已经证明，多阳离子分子，如氨基糖苷类和 双胺，能够通过自我促进摄取穿过OM，并能够作为佐剂促进 吸收其他抗生素。将合成一种可分解的双脒-抗生素给药系统，该系统 利用合成的双嘧啶能够促进束缚的抗生素在OM中的扩散 而抗生素在周质中的酶连接子裂解时释放。使用共价但可切割的 连接系统确保细胞对抗生素的摄取，而不会降低细胞内的抗生素活性。这个 这里提出的工作不仅将产生治疗MDRPA的新的高效小分子 对于感染，它还将开发一种强大的和可修改的方法来提供各种抗生素， 不能自行穿过OM进入细胞内部。这最终将增加抗生素的数量。 能够治疗这些感染，并有助于在临床上与越来越多的耐药细菌作斗争。

PROJECT SUMMARY The continued rise in the number multidrug resistant (MDR) bacterial infections, especially those caused by Gram-negative pathogens, coupled with the dearth of novel antibiotics being FDA approved in the past 3 decades has led to a dire situation that could result in millions of deaths per year worldwide if current trends continue. MDR Pseudomonas aeruginosa (PA), a Gram-negative bacterium, is one of leading causes of nosocomial infections and has been designated as a “Serious Threat” by the CDC due to lack of viable treatment options. Two barriers that must be overcome when treating MDRPA infections are wide-spread resistance to currently prescribed antibiotics with similar mechanisms of action and poor accumulation of the antibiotic in the cell due to its additional outer membrane (OM) and promiscuous efflux pumps. Therefore, antibiotics that target unexplored cellular targets in MDRPA and methods for improved antibiotic delivery to those targets must be developed. This work proposes to first probe ATP synthase, an essential protein for all life, as an underexplored target for antibiotic development by modifying the known anti-tubercular drug bedaquiline. By comparing residue differences in the BDQ binding site between Mycobacterium tuberculosis and PA, bedaquiline-like molecules capable of inhibiting PA ATP synthase selectively will be designed. This work will also give insight into the role of ATP synthase inhibition in antibiotic drug discovery. Next, a cleavable adjuvant-antibiotic hybrid strategy will be developed to overcome the OM penetration problem in PA. The OM is made up of an asymmetric bilayer of lipopolysaccharides, porins, and substrate channels, which severely limits small molecule entry into the cell by size and charge. It has been recently demonstrated that polycationic molecules, such as aminoglycosides and bisamidines, are able to cross the OM by self-promoted uptake and are able to act as adjuvants to promote the uptake of other antibiotics. A cleavable bisamidine-antibiotic drug delivery system will be synthesized that capitalizes on the synthetic bisamidine being able to promote diffusion of the tethered antibiotic across the OM and the antibiotic being released upon enzymatic linker cleavage in the periplasm. Using a covalent but cleavable linker system ensures cellular uptake of the antibiotic without reducing antibiotic activity once in the cell. The work proposed herein will not only produce new and highly efficacious small molecules to treat MDRPA infections, it will also develop a robust and modifiable method for delivering a wide variety of antibiotics that cannot cross the OM on their own to the interior of the cell. This will ultimately increase the number of antibiotics capable of treating these infections and help to combat the growing number of resistant bacteria clinically.