Details

Autor(en) / Beteiligte

• Wiesemann, Nicole
• Bütof, Lucy
• Herzberg, Martin
• Hause, Gerd
• Berthold, Lutz
• Etschmann, Barbara
• Brugger, Joël
• Martinez-Criado, Gema
• Dobritzsch, Dirk
• Baginsky, Sacha
• Reith, Frank
• Nies, Dietrich H
• Kelly, Robert M.

Titel

Synergistic Toxicity of Copper and Gold Compounds in Cupriavidus metallidurans

Ist Teil von

• Applied and environmental microbiology, 2017-12, Vol.83 (23), p.1

Ort / Verlag

United States: American Society for Microbiology

Erscheinungsjahr

2017

Link zum Volltext

Quelle

MEDLINE

Beschreibungen/Notizen

• The bacterium can reduce toxic gold(I/III) complexes and biomineralize them into metallic gold (Au) nanoparticles, thereby mediating the (trans)formation of Au nuggets. In Au-rich soils, most transition metals do not interfere with the resistance of this bacterium to toxic mobile Au complexes and can be removed from the cell by plasmid-encoded metal efflux systems. Copper is a noticeable exception: the presence of Au complexes and Cu ions results in synergistic toxicity, which is accompanied by an increased cytoplasmic Cu content and formation of Au nanoparticles in the periplasm. The periplasmic Cu-oxidase CopA was not essential for formation of the periplasmic Au nanoparticles. As shown with the purified and reconstituted Cu efflux system CupA, Au complexes block Cu-dependent release of phosphate from ATP by CupA, indicating inhibition of Cu transport. Moreover, Cu resistance of Au-inhibited cells was similar to that of mutants carrying deletions in the genes for the Cu-exporting P -type ATPases. Consequently, Au complexes inhibit export of cytoplasmic Cu ions, leading to an increased cellular Cu content and decreased Cu and Au resistance. Uncovering the biochemical mechanisms of synergistic Au and Cu toxicity in explains the issues this bacterium has to face in auriferous environments, where it is an important contributor to the environmental Au cycle. lives in metal-rich environments, including auriferous soils that contain a mixture of toxic transition metal cations. We demonstrate here that copper ions and gold complexes exert synergistic toxicity because gold ions inhibit the copper-exporting P-type ATPase CupA, which is central to copper resistance in this bacterium. Such a situation should occur in soils overlying Au deposits, in which Cu/Au ratios usually are ≫1. Appreciating how solves the problem of living in environments that contain both Au and Cu is a prerequisite to understand the molecular mechanisms underlying gold cycling in the environment, and the significance and opportunities of microbiota for specific targeting to Au in mineral exploration and ore processing.