Chen Weizhong, Wang Dan, Zhou Wenquan, Sang Hong, Liu Xichun, Ge Zhiyun, Zhang Jin, Lan Lefu, Yang Cai-Guang, Chen Hao
Department of Chemical Physics, University of Science and Technology of China, Hefei, 230026, China.
State Key Laboratory of Coordination Chemistry, School of Chemistry and Chemical Engineering, Collaborative Innovation Center of Chemistry for Life Sciences, Nanjing University, Nanjing, 210093, China.
Mol Microbiol. 2016 Jun;100(5):749-58. doi: 10.1111/mmi.13346. Epub 2016 Mar 16.
NalD was reported to be the secondary repressor of the MexAB-OprM multidrug efflux pump, the major system contributing to intrinsic multidrug resistance in Pseudomonas aeruginosa. Here, we show that novobiocin binds directly to NalD, which leads NalD to dissociate from the DNA promoter, and thus de-represses the expression of the MexAB-OprM pump. In addition, we have solved the crystal structure of NalD at a resolution of 2.90 Å. The structural alignment of NalD to its homologue TtgR reveals that the residues N129 and H167 in NalD are involved in its novobiocin-binding ability. We have confirmed the function of these two amino acids by EMSA and plate assay. The results presented here highlight the importance and diversity of regulatory mechanism in bacterial antibiotic resistance, and provide further insight for novel antimicrobial development.
据报道，NalD是MexAB - OprM多药外排泵的次要阻遏物，该系统是铜绿假单胞菌固有多药耐药性的主要贡献者。在此，我们表明新生霉素直接与NalD结合，导致NalD从DNA启动子解离，从而解除对MexAB - OprM泵表达的抑制。此外，我们已解析出分辨率为2.90 Å的NalD晶体结构。NalD与其同源物TtgR的结构比对表明，NalD中的N129和H167残基参与其与新生霉素的结合能力。我们通过电泳迁移率变动分析（EMSA）和平板试验证实了这两个氨基酸的功能。此处呈现的结果突出了细菌抗生素耐药性调控机制的重要性和多样性，并为新型抗菌药物的开发提供了进一步的见解。
