Neisseria gonorrhoeae is an obligate human pathogen and causative agent of the sexually transmitted infection (STI) gonorrhea. The most predominant and clinically important multidrug efflux system in N. gonorrhoeae is the multiple transferrable resistance (Mtr) pump, which mediates resistance to a number of different classes of structurally diverse antimicrobial agents, including clinically used antibiotics (e.g., β-lactams and macrolides), dyes, detergents and host-derived antimicrobials (e.g., cationic antimicrobial peptides and bile salts). Recently, it has been found that gonococci bearing mosaic-like sequences within the mtrD gene can result in amino acid changes that increase the MtrD multidrug efflux pump activity, probably by influencing antimicrobial recognition and/or extrusion to elevate the level of antibiotic resistance. Here, we report drug-bound solution structures of the MtrD multidrug efflux pump carrying a mosaic-like sequence using single-particle cryo-electron microscopy, with the antibiotics bound deeply inside the periplasmic domain of the pump. Through this structural approach coupled with genetic studies, we identify critical amino acids that are important for drug resistance and propose a mechanism for proton translocation.

中文翻译：

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淋球菌多药外排泵的冷冻电镜结构阐明了药物识别和耐药机制。

淋病奈瑟菌是性传播感染 (STI) 淋病的专性人类病原体和病原体。最主要的和临床上重要的多药运出系统在淋病奈瑟氏球菌是米ultiple吨ransferrable ř esistance（MTR）泵，其以多种不同的类结构不同的抗微生物剂，包括临床上使用的抗生素的介导电阻（例如，β-内酰胺和大环内酯）、染料、洗涤剂和宿主衍生的抗菌剂（例如阳离子抗菌肽和胆汁盐）。最近，已经发现在mtrD 中带有镶嵌样序列的淋球菌基因可以导致氨基酸变化，增加 MtrD 多药外排泵活性，可能是通过影响抗菌识别和/或挤出来提高抗生素耐药性水平。在这里，我们使用单粒子冷冻电子显微镜报告了 MtrD 多药外排泵的药物结合溶液结构，该泵带有镶嵌样序列，抗生素深深地结合在泵的周质域内。通过这种结构方法与遗传研究相结合，我们确定了对耐药性很重要的关键氨基酸，并提出了质子易位的机制。