The Escherichia coli copper-responsive copA promoter is activated by gold.

The copA gene of Escherichia coli encodes a copper transporter and its promoter is normally regulated by Cu(I) ions and CueR, a MerR-like transcriptional activator. We show that CueR can also be activated by gold salts and that Cys(112) and Cys(120) are involved in recognition of gold, silver, and copper salts. Gold activation is unaffected by copper chelating agents but is affected by general metal chelators. This is the first example of specific regulation of transcription by gold, and we briefly speculate that the biological effects of gold antiarthritic drugs may be through their effects on copper management in eukaryotic systems.