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Additive effects of metal excess and superoxide, a highly toxic mixture in bacteria.

ABSTRACT: Heavy metal contamination is a serious environmental problem. Understanding the toxicity mechanisms may allow to lower concentration of metals in the metal-based antimicrobial treatments of crops, and reduce metal content in soil and groundwater. Here, we investigate the interplay between metal efflux systems and the superoxide dismutase (SOD) in the purple bacterium Rubrivivax gelatinosus and other bacteria through analysis of the impact of metal accumulation. Exposure of the Cd2+ -efflux mutant ?cadA to Cd2+ caused an increase in the amount and activity of the cytosolic Fe-Sod SodB, thereby suggesting a role of SodB in the protection against Cd2+ . In support of this conclusion, inactivation of sodB gene in the ?cadA cells alleviated detoxification of superoxide and enhanced Cd2+ toxicity. Similar findings were described in the Cu+ -efflux mutant with Cu+ . Induction of the Mn-Sod or Fe-Sod in response to metals in other bacteria, including Escherichia coli, Pseudomonas aeruginosa, Pseudomonas putida, Vibrio cholera and Bacillus subtilis, was also shown. Both excess Cd2+ or Cu+ and superoxide can damage [4Fe-4S] clusters. The additive effect of metal and superoxide on the [4Fe-4S] could therefore explain the hypersensitive phenotype in mutants lacking SOD and the efflux ATPase. These findings underscore that ROS defence system becomes decisive for bacterial survival under metal excess.

SUBMITTER: Steunou AS

PROVIDER: S-EPMC7415354 | biostudies-literature | 2020 Jun

REPOSITORIES: biostudies-literature

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Additive effects of metal excess and superoxide, a highly toxic mixture in bacteria.

Steunou Anne Soisig AS Babot Marion M Bourbon Marie-Line ML Tambosi Reem R Durand Anne A Liotenberg Sylviane S Krieger-Liszkay Anja A Yamaichi Yoshiharu Y Ouchane Soufian S

Microbial biotechnology 20200619 5

Heavy metal contamination is a serious environmental problem. Understanding the toxicity mechanisms may allow to lower concentration of metals in the metal-based antimicrobial treatments of crops, and reduce metal content in soil and groundwater. Here, we investigate the interplay between metal efflux systems and the superoxide dismutase (SOD) in the purple bacterium Rubrivivax gelatinosus and other bacteria through analysis of the impact of metal accumulation. Exposure of the Cd<sup>2+</sup> -e ...[more]

PMID: 32558268

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Additive effects of metal excess and superoxide, a highly toxic mixture in bacteria.

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Additive effects of metal excess and superoxide, a highly toxic mixture in bacteria.

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