Molecular mechanisms of antibiotic resistance in Acinetobacter baumannii

 描述(由申请人提供)： 细菌病原体中的抗生素耐药性是一个巨大且迅速增长的医疗问题，影响到退伍军人和更广泛的人口的健康。使这一问题更加严重的是缺乏新药，这些因素共同威胁着我们回到抗生素出现前的时代。这项研究的目的是从分子和功能上表征一种新的关键的多粘菌素耐药性介体FlpR，它在许多医学相关的细菌病原体中都是保守的。重要的是，FlpR还参与了对至少一种宿主抗菌素的耐药性以及生物被膜的形成，因此可能在细菌的发病机制中发挥重要作用，甚至超过抗生素耐药性。研究计划我们将通过研究FlpR蛋白对革兰氏阴性细菌脂多糖(LPS)结构的影响，以及阐明其详细的作用机制，在分子水平上破译FlpR蛋白是如何在耐药中起作用的。我们将量化FlpR在体外和体内小鼠感染中对高度耐药的鲍曼不动杆菌耐药性的贡献，并确定其对毒力和生物被膜形成的贡献。方法：我们将结合遗传、分子和生化技术，阐明FlpR的作用机制及其在鲍曼不动杆菌生理和耐药性中的作用。这将包括对其在内毒素生物合成中的作用的详细研究，以及对其功能至关重要的氨基酸的剖析。临床意义鲍曼不动杆菌是一种主要的医院病原体，可引起退伍军人、士兵和平民的严重和危及生命的疾病。由于FlpR在这种和其他临床上重要的病原体(包括Francisella spp.、Bordeella spp.、Brucella spp.、军团菌嗜肺杆菌、弯曲杆菌和嗜麦芽窄食单胞菌)中是保守的，因此本提案中获得的见解将对我们对细菌性疾病的理解和治疗产生广泛的影响。此外，这项工作将为FlpR抑制剂未来的潜在开发奠定基础，甚至有利于泛耐药菌株的治疗。

 DESCRIPTION (provided by applicant): Antibiotic resistance in bacterial pathogens is an immense and rapidly growing medical problem affecting the health of veterans and the broader population. Compounding this problem is the lack of new drugs, which together threaten our return to the pre-antibiotic era. The objective of this study is to molecularly and functionally characterize a novel and critical mediator of resistance to last-line polymyxin antibiotics, FlpR, which is conserved in numerous medically relevant bacterial pathogens. Importantly, FlpR also contributes to resistance to at least one host antimicrobial, as well as biofilm formation, and thus may play an important role in bacterial pathogenesis even beyond antibiotic resistance. Research Plan We will decipher how the FlpR protein contributes to antimicrobial resistance at the molecular level, by studying its effects on the structure of Gram-negative bacterial lipopolysaccharide (LPS), as well as elucidating its detailed mechanism of action. We will quantify the contribution of FlpR to resistance in the highly antibiotic-resistant nosocomial pathogen Acinetobacter baumannii, both in vitro and in in vivo mouse infections, also determining its contribution to virulence and biofilm formation. Methods: We will use a combination of genetic, molecular, and biochemical techniques to elucidate the mechanism of FlpR action as well as its contribution to A. baumannii physiology and resistance to antimicrobials. This will include a detailed study of its role in LPS biosynthesi, as well as the dissection of amino acids that are critical to its function. Clinical Relevance A. baumannii is a major nosocomial pathogen and cause of serious and life-threatening disease in veterans, soldiers, and civilians. Since FlpR is conserved in this and other clinically important pathogens (including Francisella spp., Bordetella spp., Brucella spp., Legionella pneumophila, Campylobacter spp., and Stenotrophomonas maltophilia), the insights gained in this proposal will have a broad impact on our understanding and treatment of bacterial disease. Furthermore, this work will lay the foundation for the potential future development of FlpR inhibitors, facilitating the treatment of even pan-resistant strains.