Fig 3.

CzcS/CzcR positively regulates Cu tolerance through PtrA during Zn excess. (A) Growth of the WT strain and the ΔczcR mutant in the presence or absence of 2 mM CuSO₄ when the strains were not pretreated with Zn. (B) Growth of the WT strain and the ΔczcR mutant in the presence or absence of 2 mM CuSO₄ after the strains were pretreated with Zn. (C) Growth of the WT strain, ΔczcR mutant, and the ΔczcR mutant with the overexpression of ptrA, PA2807, or ptrA-PA2807 in the presence of 2 mM CuSO₄ when the strains were not pretreated with Zn. (D) Growth of the WT strain, ΔczcR mutant, and the ΔczcR mutant with the overexpression of ptrA, PA2807, or ptrA-PA2807 in the presence of 2 mM CuSO₄ after the strains were pretreated with Zn.