Additive effects of metal excess and superoxide, a highly toxic mixture in bacteria. Issue 5 (19th June 2020)

• Record Type: Journal Article
• Authors: Steunou, Anne Soisig; Babot, Marion; Bourbon, Marie‐Line; Tambosi, Reem; Durand, Anne; Liotenberg, Sylviane; Krieger‐Liszkay, Anja; Yamaichi, Yoshiharu; Ouchane, Soufian
• Is Part Of: Microbial biotechnology. Volume 13:Issue 5(2020:Sep.)
• Page Start: 1515
• Page End: 1529
• Publication Date: 2020-06-19
• Subjects: Microbial biotechnology -- Periodicals; Biotechnology; Microbiology; 660.62
• DOI: 10.1111/1751-7915.13589
• Languages: English
• ISSNs: 1751-7915

Abstract

Summary: 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 2+ ‐efflux mutant Δ cadA to Cd 2+ caused an increase in the amount and activity of the cytosolic Fe‐Sod SodB, thereby suggesting a role of SodB in the protection against Cd 2+ . In support of this conclusion, inactivation of sodB gene in the Δ cadA cells alleviated detoxification of superoxide and enhanced Cd 2+ 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 Cd 2+ 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. Abstract : Superoxide detoxification system became determinant for bacterial survival under metal stress in bacteria. Targeting the ROS defense system together with the metal efflux systems may allow lowering the concentration of metals in the metal‐based antimicrobial treatments in agriculture and farming.