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.

Key words: E.coli, heavy metal tolerance, AtGCS, GSH, accumulation