Substrate binding domain of ferric iron-binding protein, a member of the type 2 periplasmic binding fold superfamily.
FutA1 is the periplasmic component of an ABC-type iron transporter and serves as the primary receptor in Synerchosystis species. The periplasmic iron binding protein plays an essential role in the iron uptake pathway of Gram-negative pathogenic bacteria and is critical for survival of these pathogens within the host. After binding iron with high affinity, FutA1 interact with a cognate membrane transport complex comprised of two integral membrane domains and two cytoplasmically located ATPase. This interaction triggers the ligand translocation across the cytoplasmic membrane energized by ATP hydrolysis. The iron- and thiamine-binding proteins belong to the PBPI2 superfamily of periplasmic binding proteins that differ in size and ligand specificity, but have similar tertiary structures consisting of two globular subdomains connected by a flexible hinge. They have been shown to bind their ligand in the cleft between these domains in a manner resembling a Venus flytrap.
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