Transporter of a GTP-driven Fe(2+) uptake system, probably couples GTP-binding to channel opening and Fe(2+) uptake (PubMed:12446835, PubMed:19629046). A guanine nucleotide-binding protein (G proteins) in which the guanine nucleotide binding site alternates between an active, GTP-bound state and an inactive, GDP-bound state. This protein has fast intrinsic GDP release, mediated by the G5 loop (about residues 149-158). Presumably GTP hydrolysis leads to conformational changes and channel closing (PubMed:19629046). A GDP release mechanism involving a conformational change of the G5 loop (and thus the removal of the nucleotide-binding and stabilizing interactions) would significantly reduce the affinity for GDP, and conceivably be sufficient for catalysing nucleotide release (PubMed:25374115). The isolated N-terminal domain (residues 1-274) forms trimers (PubMed:19629046, Ref.10,PubMed:25374115). Iron uptake is repressed by the global regulator Fur in presence of Fe(2+) (PubMed:12446835). Induced by hydroxyurea (PubMed:20005847). Contains a guanine-nucleotide-specific nucleotide-binding site (about residues 1-276) that shows slow GTP hydrolysis (PubMed:12446835, PubMed:23104801). When a non-hydrolyzable GTP analog binds to the trimeric N-terminal domain, it induces a structural shift which opens a pore (PubMed:19629046). Poor uptake of Fe(2+). Belongs to the TRAFAC class TrmE-Era-EngA-EngB-Septin-like GTPase superfamily. FeoB GTPase (TC 9.A.8) family.