Part of an ABC transporter complex involved in ferric-petrobactin uptake. Can probably form at least three ABC transporter complexes, composed of two ATP-binding proteins (FpuC or FpuD), two transmembrane proteins (FpuB) and a solute-binding protein (FpuA), or composed of two ATP-binding proteins (FatE), two transmembrane proteins (FatC and FatD) and a solute-binding protein (FpuA). Deletion mutant exhibits a growth defect in iron-depleted media. Mutant is able to produce and secrete petrobactin, but petrobactin accumulates in the culture supernatants. Mutant is also significantly attenuated in a murine model of inhalational anthrax. Belongs to the bacterial solute-binding protein 8 family.