Tigecycline efflux in Acinetobacter baumannii is mediated by TetA in synergy with RND-type efflux transporters
Tigecycline efflux in Acinetobacter baumannii is mediated by TetA in synergy with RND-type efflux transporters
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DOI：
10.1093/jac/dkaa015
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发表时间：
2020-05-01
影响因子：
5.2
通讯作者：
Pos, Klaas M.
中科院分区：
文献类型：
--
作者：
Foong, Wuen Ee;Wilhelm, Jochen;Pos, Klaas M.
目的：研究鲍曼不动杆菌AYE主要易化因子超家族（MFS）型转运蛋白在替加环素外排中的作用。鲍曼不动杆菌AYE（tetA和tetG）在大肠杆菌中异源表达，并用替加环素和三种其他四环素衍生物进行药物敏感性测定。TetA在替加环素在A.通过tetA在WT和抗性结瘤细胞分裂（RND）基因敲除菌株中的互补来确定鲍曼不动杆菌。鲍曼不动杆菌ATCC 19606。MFS型tetA基因和RND外排泵基因adeB、adeG和adeJ在A.结果：TetA或TetG的过量表达使大肠杆菌对强力霉素、米诺环素和四环素产生耐药性。杆菌表达tetA而非表达tetG的细胞赋予替加环素抗性，这意味着TetA是替加环素转运的决定因素。A.与非互补菌株相比，用质粒编码的tetA互补的鲍曼不动杆菌WT和RND敲除菌株对替加环素的敏感性显著降低。外排泵基因tetA和adeG在A.结论：TetA在替加环素外排中起重要作用。通过将药物从细胞质移到周质，随后，RND型转运蛋白AdeABC和AdeIK将替加环素挤出穿过外膜。当用替加环素激发时，tetA在A.鲍曼不动杆菌TetA和RND型转运蛋白AdeABC和/或AdeIJK之间的协同作用对于A.鲍曼不动杆菌通过药物外排赋予更高的替加环素耐药性。
Objectives: To investigate the role of Major Facilitator Superfamily (MFS)-type transporters from Acinetobacter baumannii AYE in tigecycline efflux.Methods: Two putative tetracycline transporter genes of A. baumannii AYE (tetA and tetG) were heterologously expressed in Escherichia coli and drug susceptibility assays were conducted with tigecycline and three other tetracycline derivatives. The importance of TetA in tigecycline transport in A. baumannii was determined by complementation of tetA in WT and Resistance Nodulation cell Division (RND) gene knockout strains of A. baumannii ATCC 19606. Gene expression of the MFS-type tetA gene and RND efflux pump genes adeB, adeG and adeJ in A. baumannii AYE in the presence of tigecycline was analysed by quantitative real-time RT-PCR.Results: Overproduction of TetA or TetG conferred resistance to doxycycline, minocycline and tetracycline in E. coli. Cells expressing tetA, but not those expressing tetG, conferred resistance to tigecycline, implying that TetA is a determinant for tigecycline transport. A. baumannii WT and RND-knockout strains complemented with plasmid-encoded tetA are significantly less susceptible to tigecycline compared with non-complemented strains. Efflux pump genes tetA and adeG are up-regulated in A. baumannii AYE in the presence of subinhibitory tigecycline concentrations.Conclusions: TetA plays an important role in tigecycline efflux of A. baumannii by removing the drug from cytoplasm to periplasm and, subsequently, the RND-type transporters AdeABC and AdeIJK extrude tigecycline across the outer membrane. When challenged with tigecycline, tetA is up-regulated in A. baumannii AYE. Synergy between TetA and the RND-type transporters AdeABC and/or AdeIJK appears necessary for A. baumannii to confer higher tigecycline resistance via drug efflux.