The Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, 1800 Lihu Road, Wuxi, People's Republic of China.
State Key Laboratory of Food Science and Technology, Jiangnan University, Wuxi, People's Republic of China.
Appl Microbiol Biotechnol. 2022 May;106(9-10):3679-3689. doi: 10.1007/s00253-022-11971-6. Epub 2022 May 18.
The MarR family, as multiple antibiotic resistance regulators, is associated with the resistance of organisms to unfavorable conditions. MarR family extracellular polymeric substances (EPS)-associated transcriptional regulator (EpsR) was closely associated with copper resistance in Acidithiobacillus caldus (A. caldus). Transcriptional analysis showed high activity of the epsR promoter (PI) in Escherichia coli and differential response to metal ions. The copper content and UV absorption spectrum of the co-purified protein did not increase, but a stoichiometry of 0.667 mol Cu(I) per EpsR monomer was observed in vitro in copper titration experiments, suggesting that Cu(II) acts with low affinity in binding to the EpsR protein. Electrophoretic mobility shift assays (EMSA) demonstrated that EpsR could bind to its own promoter in vitro, and the binding region was the palindrome sequence TGTTCATCGTGTGTGAGCACACA. EpsR negatively regulated its own gene expression, whereas Cu(II) mitigates this negative effect. EpsR did not bind to other neighboring gene promoters. Finally, we developed a working model to illustrate the regulatory mechanism of A. caldus in response to extreme copper stress. KEY POINTS: • Identification of a MarR family EPS-associated transcriptional regulator, named EpsR. • Cu(I) can bind to the EpsR protein with low affinity. • EpsR negatively regulates the expression of epsR, and Cu(II) can alleviate this negative regulation.
MarR 家族作为多种抗生素耐药调节剂，与生物体对不利条件的耐药性有关。MarR 家族细胞外聚合物质（EPS）相关转录调节剂（EpsR）与嗜酸硫杆菌（A. caldus）的铜抗性密切相关。转录分析显示，epsR 启动子（PI）在大肠杆菌中活性很高，对金属离子有不同的反应。共纯化蛋白的铜含量和紫外吸收光谱没有增加，但在铜滴定实验中体外观察到 0.667 mol Cu（I）/ EpsR 单体的化学计量比，表明 Cu（II）与 EpsR 蛋白结合的亲和力较低。电泳迁移率变动分析（EMSA）表明，EpsR 可以在体外与其自身启动子结合，结合区域为回文序列 TGTTCATCGTGTGTGAGCACACA。EpsR 负调控自身基因表达，而 Cu（II）减轻了这种负调控作用。EpsR 不会与其他相邻基因启动子结合。最后，我们提出了一个工作模型来阐明 A. caldus 应对极端铜胁迫的调控机制。关键点：
鉴定了一种 MarR 家族 EPS 相关转录调节剂，命名为 EpsR。
Cu（I）与 EpsR 蛋白的结合亲和力较低。
EpsR 负调控 epsR 的表达，而 Cu（II）可以减轻这种负调控作用。
