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作 者 ：刘大丽;毛子军;安志刚*;马龙彪;鲁振强

期 刊 ：植物研究 2013年 33卷 (3)期 页码：325-329

关键词：大肠杆菌；重金属耐受性；AtGCS；GSH；

Keywords:E.coli, heavy metal tolerance, AtGCS, GSH, accumulation,

摘 要 ：谷胱甘肽（GSH）是一类在生物体内广泛存在，并且是十分重要的重金属毒害保护剂之一。本研究将编码拟南芥γ-谷氨酰半胱氨酸合成酶基因AtGCS（GSH合成的关键酶之一）转化到大肠杆菌（BL21）中，通过IPTG诱导过量表达TrxA-AtGCS融合蛋白来分析AtGCS在提高大肠杆菌重金属耐受性方面的作用。过量表达TrxA的大肠杆菌被用作对照。研究结果表明，在1 mmol·L^-1 Cd²⁺、Zn²⁺或Cu²⁺重金属胁迫下，过量表达TrxA-AtGCS的大肠杆菌细胞的生长状态要明显优于表达TrxA的对照细胞。同时，过量表达TrxA-AtGCS的大肠杆菌表现出超出对照细胞5倍以上的Cd²⁺、Zn²⁺和Cu²⁺累积量和4倍以上的GSH含量，其中，高于对照10倍的Cd²⁺富集量尤为明显。因而可以得出结论，拟南芥AtGCS的大量表达大大提升了大肠杆菌的谷胱甘肽含量，从而使GSH可以直接或间接地富集更多的重金属离子，进而提高了大肠杆菌对重金属逆境的抗性。

Abstract:GSH is one of the most ubiquitous proteins known to provide protection against toxic heavy metals. A gene-AtGCS encoding Arabidopsis γ-glutamylcysteine synthetase was introduced into E.coli (BL21) by over-expression of TrxA-AtGCS fusion protein to analyze the capacity to enhance heavy metal tolerance of transformed E.coli. As a comparison, strain over-expressing only TrxA was used as a control. The results showed that the growth of E.coli cells by over-expressing TrxA-AtGCS was much better than the control cells expressing TrxA under 1 mmol·L^-1 Cd²⁺, Zn²⁺ and Cu²⁺ heavy metal stresses. Meanwhile, more than 5 times’ bioaccumulation of Cd²⁺, Zn²⁺, Cu²⁺ and more than 4 times’ GSH content were observed in the strain over-expressing TrxA-AtGCS relatively to control cells, especially under cadmium ions with 10 times’ accumulation in cells over-expressing TrxA-AtGCS. It could be concluded that over-expression of AtGCS offered a promising heavy metal resistance of E.coli with superior heavy metal accumulation and GSH content.

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