鲍曼不动杆菌是导致医院严重肺炎和血流感染的病原菌，其临床检出率日益增高且多重耐药问题日趋严重，已经成为临床抗感染治疗的重要挑战。鲍曼不动杆菌的多重耐药性与其跨膜RND家族药物外排泵介导的抗生素外排密切相关。本项目将筛查临床感染多重耐药鲍曼不动杆菌中三种RND药物外排泵AdeABC，AdeIJK，AdeFGH及其调控元件AdeRS，AdeN，AdeL的基因多态性；然后通过一体化结构生物学方案，解析其调控元件识别靶向DNA调控序列的晶体结构，在原子水平阐述其调控机制；进而整合X射线晶体学和冷冻电镜揭示药物外排泵跨膜复合物外排抗生素底物的结构机制；最后构建基因敲除和点突变菌株，验证在临床感染样本中的多态性和结构解析获得关键氨基酸调控位点对其多重耐药的影响，在临床，结构和生理水平三个尺度系统揭示RND药物外排泵介导鲍曼不动杆菌多重耐药的分子机制，为研发新的抗生素药物和抗感染治疗策略提供重要依据。

Acinetobacter baumannii is an important hospital-acquired pathogen causing serious pneumonia and bloodstream infections, within its clinical detection rate getting higher and multidrug resistance problem becoming more and more serious, the World Health Organization has ranked it as the most critical multidrug-resistant pathogenic bacteria all over the world...Acinetobacter baumannii multidrug resistant ability is highly correlated with its RND (Resistance-Nodulation-Division) family efflux pump anchored across the cell membrane, which can efflux antibiotics out of the cell under antimicrobial pressure. There are three RND efflux pumps, namely AdeABC, AdeIJK and AdeFGH in Acinetobacter baumannii, and they are strictly controlled by AdeRS two-component regulatory system, transcriptional regulator AdeN, and AdeL respectively...Here we will screen the gene polymorphism of the RND efflux pump together with their regulatory elements from the clinical Acinetobacter baumannii strains. Following by an integrative structural biology approach, we will reveal the atomic crystal structure of the regulatory elements AdeRS, AdeN and AdeL targeting their promoter DNA sequence to elucidate the RND efflux pump regulatory mechanism. More importantly, we will combine X-ray crystallography and cryo-Electron Microscopy to solve the structure of RND efflux pump transmembrane complex and demonstrate its efflux mechanism. Finally the knockout and mutagenesis strains will be generated and used to verify the key regulatory residues involved in the multidrug resistance from the clinical infection sample's gene polymorphisms and structural studies...Taken together, we will carry out the clinical, structural and physiological studies to reveal the mechanism insight into how RND efflux pump mediate the multidrug resistance in Acinetobacter baumannii, and our study will enlighten the antimicrobial drug discovery by targeting RND efflux pump and will pave the way for anti-infective therapy against Acinetobacter baumannii.