Figure 9. Schematic representation of the putative mechanism of action of FeoB from P. aeruginosa acting as a GTP-gated Fe²⁺ channel.

Fe²⁺ in the periplasm binds to Cys⁶⁷⁵, which acts as a Fe²⁺ sensor. Fe²⁺ binding signals the G-domain to initiate the binding of GTP. Either GTP binding or GTP hydrolysis results in conformational changes that subsequently open the pore lined by Cys⁴²⁹, allowing Fe²⁺ to pass down its concentration gradient.