Figure 5. PspA facilitates ZupT-dependent growth of Salmonella in Zn²⁺-chelated medium.

Overnight cultures of S. Typhimurium 14028s were inoculated to 4×10⁵ CFU/ml in LB supplemented with dipyridyl (DP), with or without 500µM ZnCl₂, and growth monitored for 18h at 37°C. Analysis was performed on strains containing combinations of the following mutations: mntH (M), sitA (S), feoB (F), ΔzupT (Z) ΔznuABC (N), and ΔpspA (P). A. To assess ZupT-dependent Zn²⁺ transport, growth of S. Typhimurium MSFN with the pRB3 vector (purple diamond) was compared with strains MSFNP/pRB3 (red diamond) and MSFNP/pspA plasmid pJK664 (green diamond) in LB with 400µM dipyridyl alone or with the addition of 500µM ZnCl₂. B. Growth of S. Typhimurium MSFNZ with the pRB3 vector (blue square) was compared with strains MSFNZ/zupT plasmid pJK671 (blue circle), MSFNZP/pRB3 (red square), and MSFNZP/pJK671 (red circle) grown in LB with 525µM dipyridyl alone or with the addition of 500µM ZnCl₂.