Ezemaduka Anastasia N, Lv Yanchun, Wang Yunbiao, Xu Jingbo, Li Xiujun
Key Laboratory of Wetland Ecology and Environment, Northeast Institute of Geography and Agroecology, Chinese Academy of Sciences, Changchun 130012, China.
School of Environment, Northeast Normal University, Changchun 130024, China.
J Therm Biol. 2018 Feb;72:137-142. doi: 10.1016/j.jtherbio.2018.01.007. Epub 2018 Jan 31.
Small heat shock proteins (sHSPs) are ubiquitous stress proteins that are able to protect the cells against cellular insults from temperature, heavy metal etc. However, the molecular chaperone roles of sHSPs in enhancing growth and adaptation under combined temperature and metal stresses in Escherichia coli cells have been poorly understood. Here, we analyze the function of recombinant AgsA, a small heat shock protein from Salmonella enterica serovar Typhimurium under combined temperature and zinc stress in E. coli. Our results show that the heterologous expression of AgsA significantly increases the tolerance of E. coli cells to the combined effect of temperature stress and zinc toxicity by maintaining the stability of soluble proteins. Furthermore, there was remarkable and significant difference in the half effect concentration (EC50) of zinc at all temperatures treatments in both test cells. The EC50s of zinc at 37 °C, 42 °C and 50 °C were 15.24 mg/L, 29.30 mg/L, and 5.98 mg/L respectively in the AgsA-transformed E. coli cells, and 3.03 mg/L, 2.38 mg/L, and 0.373 mg/L, respectively in the control cells lacking AgsA. Together, our data indicate a good concentration-response relationship between all three temperatures treatment and zinc toxicity in E. coli, and establish for the first time the combined effects of temperature and zinc toxicity on E. coli cells. Also, the AgsA protein response to combined thermal and metal stress could serve as a molecular biomarker for the assessment of interactive stress damage to the cells.
小分子热休克蛋白（sHSPs）是普遍存在的应激蛋白，能够保护细胞免受温度、重金属等细胞损伤。然而，小分子热休克蛋白在大肠杆菌细胞中，在温度和金属联合胁迫下增强生长和适应性方面的分子伴侣作用，目前还知之甚少。在此，我们分析了重组AgsA的功能，AgsA是一种来自鼠伤寒沙门氏菌的小分子热休克蛋白，在大肠杆菌中处于温度和锌联合胁迫条件下。我们的结果表明，AgsA的异源表达通过维持可溶性蛋白质的稳定性，显著提高了大肠杆菌细胞对温度胁迫和锌毒性联合作用的耐受性。此外，在所有温度处理下，两种测试细胞中锌的半数效应浓度（EC50）存在显著差异。在转AgsA基因的大肠杆菌细胞中，37℃、42℃和50℃时锌的EC50分别为15.24mg/L、29.30mg/L和5.98mg/L，而在缺乏AgsA的对照细胞中分别为3.03mg/L、2.38mg/L和0.373mg/L。总之，我们的数据表明，在大肠杆菌中，所有三种温度处理与锌毒性之间存在良好的浓度-反应关系，并首次确定了温度和锌毒性对大肠杆菌细胞的联合作用。此外，AgsA蛋白对热和金属联合胁迫的反应可作为评估细胞交互应激损伤的分子生物标志物。
