Effect of Ag+ (1-5 mM) on transcription of cus and cue genes. (A) Expression of cusCFBA and cusRS was upregulated in the presence of 1mM Ag+ that increased with higher concentrations of Ag+ upto 3mM. However, further increase in the metal resulted in lesser upregulation. (B) Transcription of cue regulon genes (copA, cueO and cueR) also upregulated in the presence of Ag+. In this case, maximum upregulation was observed at 1mM Ag. cue regulon was found to be 6 times more upregulated as compared to cus regulon in response to the metal.