Cadmium toxicity is alleviated by AtLCD and AtDCD in Escherichia coli.

AIMS:Arabidopsis thaliana l- and d-cysteine desulfhydrases (AtLCD and AtDCD) are two important H(2) S-generating enzymes. This study determined the effects of H(2) S derived from AtLCD and AtDCD on cadmium (Cd) toxicity in Escherichia coli. METHODS AND RESULTS:AtLCD and AtDCD were cloned into pET28a vectors and transformed into wild-type E. coli strain BL21(DE3), named BL21(LCD) and BL21(DCD). In the induced BL21(LCD) and BL21(DCD) compared with wild type, significantly higher H(2) S generation rates were observed. Additionally, higher survival rates, reduced contents of malondialdehyde (MDA) and hydrogen peroxide (H(2) O(2)), decreased activities of superoxide dismutase and catalase under 220 μmol l(-1) Cd stress were noted. We obtained similar results in the wild type treated with NaHS, a H(2) S donor. The above changes were substantially counteracted by the mixture of ammonia and pyruvic acid potassium (NH(3) + C(3) H(3) KO(3)), a synthetic inhibitor of H(2) S. CONCLUSIONS:AtLCD and AtDCD catalyse the H(2) S production, generating an ameliorating effect against Cd-induced oxidative stress and resulting in E. coli resistance to Cd toxicity. SIGNIFICANCE AND IMPACT OF THE STUDY:H(2) S as a gasotransmitter is certified to have an ameliorating effect against Cd toxicity, thus providing information for further research regarding the role of H(2) S in regulating resistance to the heavy metal stress in organisms.

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