Sun Jun-Ren, Jeng Wen-Yih, Perng Cherng-Lih, Yang Ya-Sung, Soo Po-Chi, Chiang Yen-Sen, Chiueh Tzong-Shi
Division of Clinical Pathology, Department of Pathology, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan, Republic of China.
University Center for Bioscience and Biotechnology, National Cheng Kung University, Tainan 701, Taiwan, Republic of China Department of Biochemistry and Molecular Biology, National Cheng Kung University, Tainan 701, Taiwan, Republic of China.
J Antimicrob Chemother. 2016 Jun;71(6):1488-92. doi: 10.1093/jac/dkw002. Epub 2016 Feb 4.
Amino acid substitutions within the AdeRS two-component system are believed to result in overexpression of the AdeABC efflux pump and extensive resistance to antibiotics in clinical Acinetobacter baumannii isolates. However, the exact amino acid substitutions in AdeRS that cause overexpression of the AdeABC efflux pump remain unclear. We elucidated the role of amino acid substitutions in AdeRS by a complementation assay in an adeRS knockout strain of A. baumannii.
Five types of adeRS operon from tigecycline-resistant XDR A. baumannii (XDRAB) were cloned and introduced into the adeRS knockout strain to reverse its tigecycline susceptibility.
Through shuffling gene segments among those five adeRS operons and performing site-directed mutagenesis, we found that the specific amino acid substitution Gly186Val in AdeS is crucial for reducing tigecycline susceptibility of A. baumannii.
Our result demonstrates that a critical amino acid substitution in AdeS alters the AdeABC efflux pump-mediated tigecycline resistance of A. baumannii.
人们认为，临床鲍曼不动杆菌分离株中双组分系统AdeRS内的氨基酸替换会导致AdeABC外排泵过度表达，并产生广泛的抗生素耐药性。然而，导致AdeABC外排泵过度表达的AdeRS中确切的氨基酸替换仍不清楚。我们通过在鲍曼不动杆菌adeRS基因敲除菌株中进行互补试验，阐明了AdeRS中氨基酸替换的作用。
从耐替加环素的广泛耐药鲍曼不动杆菌（XDRAB）中克隆出五种类型的adeRS操纵子，并将其导入adeRS基因敲除菌株，以恢复其对替加环素的敏感性。
通过在这五个adeRS操纵子之间改组基因片段并进行定点诱变，我们发现AdeS中特定的氨基酸替换Gly186Val对于降低鲍曼不动杆菌对替加环素的敏感性至关重要。
我们的结果表明，AdeS中的关键氨基酸替换改变了鲍曼不动杆菌中AdeABC外排泵介导的对替加环素的耐药性。
