Characterization of RaeE-RaeF-RopN, a putative RND efflux pump system in Riemerella anatipestifer

文献类型： 外文期刊

第一作者： Wang, Yanping

作者： Wang, Yanping;Li, Shengdou;Gong, Xiaowei;Chen, Qiwei;Ji, Guo;Liu, Yongsheng;Zheng, Fuying

作者机构：

关键词： Riemerella anatipestifer; RaeE-RaeF-RopN; RND efflux system

期刊名称：VETERINARY MICROBIOLOGY （ 影响因子：3.293； 五年影响因子：3.599 ）

ISSN： 0378-1135

年卷期： 2020 年 251 卷

页码：

收录情况： SCI

摘要： Resistance-nodulation-division (RND) efflux systems are ubiquitous in Gram-negative bacteria and play a pre dominant role in antimicrobial resistance and other diverse phenotypes, but the knowledges of RND efflux systems are poorly understood so far in Riemerella anatipestifer. According to the sequence annotation, RIA_1117-RIA_1118-RIA_1119 operon in RA-GD strain encodes a putative tripartite RND efflux system. RIA_1117, RIA_1118 and RIA_1119 genes encode an outer member protein (OMP), an inner membrane pump protein (pump transporter), and a periplasmic membrane fusion protein (MFP), respectively. Furthermore, RIA_1119 protein is annotated as a MexE component. In this work, the biological functions of RIA_1117-RIA_1118-RIA_1119 proteins were studied. The antibiotic susceptibility testing showed that the inactivation of RIA_1117, RIA_1118 and RIA_1119 genes all raised susceptibility to amikacin, streptomycin and SDS. By induction with the above antimicrobial agents, the transcription levels of RIA_1117 and RIA_1118 genes were up-regulated significantly using qRT-PCR detection, but no significance difference was observed for the transcription level of RIA_1119 gene. CCCP inhibitor assay confirmed that RIA_1117, RIA_1118 and RIA_1119 proteins mediated amikacin, streptomycin and SDS resistance depending on proton motive force (PMF). Spot assay and streptomycin accumulation assay confirmed that RIA_1117, RIA_1118 and RIA_1119 proteins contributed to export streptomycin, and CCCP increased the accumulation of streptomycin. Furthermore, RIA_1117, RIA_1118 and RIA_1119 proteins also were involved in the fitness and virulence of RA-GD strain. These results showed that RIA_1117-RIA_1118-RIA_1119 operon encoded a RND efflux system, which has the substrate specificity for streptomycin, amikacin and SDS and contributed to the growth and virulence of RA-GD. RIA_1117-RIA_1118-RIA_1119 was designated RaeE-RaeFRopN efflux system. Based on the above results and structural analysis, RIA_1117, RIA_1118 and RIA_1119 proteins corresponded to RopN (OMP), RaeF (pump transporter) and RaeE (MFP), respectively.

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