鲍曼不动杆菌铁蛋白的抗氧化功能研究

【目的】克隆鲍曼不动杆菌铁蛋白(Abferritin)基因,并研究其抗氧化功能。【方法】荧光定量PCR检测氧化应激下Abferritin基因的表达量,并将其基因克隆到表达载体p ET28a以构建重组质粒p ET28a-Abferritin,转化大肠杆菌BL21(DE3)得到重组菌BL/p ET28aAbferritin,IPTG诱导目的蛋白表达并利用镍柱亲和层析纯化该蛋白。比色法测定Abferritin蛋白的Fe2+氧化酶活性,自由基清除实验测定其抗氧化功能。菌落计数法观察重组大肠杆菌在H2O2应激条件下的存活率。【结果】Abferritin基因在氧化应激下表达增高。重组质粒在大肠杆菌BL21(DE3)中高效表达,通过Ni2+亲和层析纯化获得了Abferritin蛋白。该蛋白具有Fe2+氧化酶活性,能有效减少氧自由基的形成及提高大肠杆菌抵抗氧化应激的能力。【结论】氧化应激能诱导Abferritin基因表达上调,且该蛋白具有亚铁氧化酶活性和抗氧化功能。

The anti-oxidative activity of Acinetobacter baumannii ferritin protein

Objective] This study aimed to clone the ferritin gene Abferritin from Acinetobacter baumannii and identify its anti-oxidative activity. Methods] Relative expression of Abferritin under oxidative stress was analyzed by real-time PCR. The gene encoding sequence of Abferritin was inserted into the pET28a vector to generate the pET28a-Abferritin recombinant plasmid. This plasmid was transformed into the E. coli BL21(DE3) to create transformed strain of BL/pET28a-Abferritin. The Abferritin protein was expressed by IPTG induction and was purified by Ni2+-affinity chromatography. Kinetics of Fe2+ oxidation which catalyzed by Abferritin protein was determined by spectrophotometric analysis. Anti-oxidative activity of Abferritin was examined by the radical scavenging assay. Survival rations of the recombinant and control E. coli under the oxidative stress of H2O2 were also measured. Results] Expression level of Abferritin was up-regulated in A. baumannii under oxidative stress. Abferritin protein was expressed in E. coli BL21(DE3) and was purified successfully. Ferroxidase activity assay demonstrated that the Abferritin protein could convert Fe2+ to Fe3+. The hydroxyl radicals were scavenged by the Abferritin protein in vitro and the ectopic expression of Abferritin could increase the survival ratios of E. coli cells under the oxidative stress. Conclusion] Abferritin was strongly up regulated under oxidative stress and the Abferritin protein exhibited ferroxidase and anti-oxidative activity.