小分子热休克蛋白AgsA过量表达提高大肠杆菌的抗热性

Enhanced thermotolerance of Escherichia coli by over- expressing a heat- shock protein AgsA

目的探讨来自鼠伤寒沙门氏菌的小分子热休克蛋白AgsA过量表达对大肠杆菌（E．coli）抗热性的影响。方法将重组质粒pET21a—agsA转化到E．coliBL21（DE3）感受态细胞中，表达AgsA蛋白，并对其进行纯化。分别以乙醇脱氢酶和过氧化氢酶作为底物，检测AgsA蛋白的分子伴侣活性。将过量表达AgsA的E．coli在不同温度下处理，检测AgsA对Ecoli的热保护作用。结果重组质粒pET21a—agsA转化到E．coliBL21（DE3）感受态细胞之后，诱导目的蛋白表达，经纯化，获得高纯度的AgsA蛋白。该蛋白可以在体外阻止乙醇脱氢酶和过氧化氢酶在高温条件下发生的聚集。体内过量表达AgsA蛋白可以显著提高大肠杆菌的抗热性。结论AgsA蛋白通过其分子伴侣活性阻止大肠杆菌体内蛋白在高温下发生的聚集，从而提高大肠杆菌在高温环境下的生存率。

Objective To investigate the effects of over - expression of a small heat - shock protein AgsA from Salmonella enterica serovar Typhimurium on the thermotolerance of Escherichia coli （E. coli）. Methods A recombinant vector pET21a- agsA was transformed into E. coli BL21 （DE3） competent cells to express AgsA protein before purification. Then, both alcohol dehydrogenase and catalase were adopted as substrates to measure the chaperone activity of AgsA. This protein was further over - expressed to investigate its effects on the thermotolerance of E. coli. Results After transformation of the recombinant vector pET21 a -agsA into E. coli BI221 （DE3） competent cells, AgsA protein was induced and purified with a high purity. The resultant protein could in vitro prevent the aggregation of alcohol dehydrogenase and catalase under high temperatures. Over - expression of this protein in vivo could significantly enhance the thermotolerence of E. coll. Conclusion AgsA can prevent the aggregation of proteins within E. coli due to its chaperone activity under higher temperatures, yielding an improved survival of E. coll.