Fig 5.

Analysis of the roles of residues at positions 113 and 118 in Salmonella CueR. (A) Sequence of the MBL of GolS, CueR, and the mutant alleles CueR_P113A, CueR_A118P, and CueR_{P113A A118P}. (B and C) β-Galactosidase activity from a copA::lacZ transcriptional fusion expressed from a reported plasmid by cells carrying cueR (CueR) or the mutant alleles coding for CueR_L, CueR_P113A, CueR_A118P, or CueR_{P113A A118P} in an otherwise wild-type (B) or ΔgolS (C) genetic background. Cells were grown overnight in LB broth without (−) or with the addition of 40 μM AuHCl₄ (Au) or 1 mM CuSO₄ (Cu). The data correspond to mean values of four independent experiments performed in duplicate. Error bars correspond to the standard deviations. Differences in β-galactosidase activity values from the wild-type CueR and CueR_{P113A A118P} in the presence of Cu were statistically significant (*, P = 0.029; **, P = 0.001). No significant differences were observed from wild-type CueR and CueR_A118P in the presence of Cu.