FIG 1.

Schematic of copper trafficking in S. Typhimurium. Copper gains entry to the periplasm via nonspecific porins or transporters. In the periplasm, Cu¹⁺ can be oxidized by CueO to Cu²⁺. Cu¹⁺ can cross the inner membrane via unspecified mechanisms. CueR and GolS are transcriptional regulators that bind Cu and activate target gene expression. CopA and GolT are inner membrane P-type ATPases that pump copper back to the periplasm, where it can be bound by CueP. CueP can deliver copper to SodCI and SodCII. SodCI and SodCII are also able to acquire copper via CueP-independent mechanisms. During infection, phagocytes upregulate expression of a copper-specific transporter, ATP7A, that potentially pumps copper into the phagosome.