Effect of the lexA gene of deinococcus radiodurans on the resistance of escherichia coli to γ-rays and MMC

The work is to study the effect of lexA gene of Deinococcus radiodurans expressed in Escherichia coli on its resistance to y-rays and MMC. Recombinant plasmid pZA172 was constructed by cloning the lexA gene of Deinococcus radiodurans into the vector plasmid PUC 19 in the downstream of lacZ promoter. Transfected Escherichia coli strain JM109(pZA172) was obtained through transfection of JM109 strain with pZA172 by electropo-ration. Expression of the lexA protein in the IPTG-INDUCED JM109 (Pzal72) was checked by SDS-PAGE, and survival curve of the strain was measured using colony formation assay after treatment with different doses of radiation and different concentrations of MMC. After IPTG induction, the lexA protein was significantly expressed in the strain JM109 (pZA172), and the survival rate of the strain was higher than that of the control. The expression of Deinococcus radiodurans lexA gene in Escherichia coli resulted in the increase of sensitivity of the latter to y-rays and MMC. Mechanism of the effect remains to be further investigated.