The Heme in Bacterioferritin Is Crucial to Bacterial Iron Homeostasis

Ferritin-like molecules are unique to cellular iron homeostasis because they can store iron at concentrations much higher than those dictated by the solubility of Fe³⁺. However, very little is known about the protein interactions that deliver iron for storage or promote the mobilization of stored iron from ferritin-like molecules. Bacterioferritins, which are iron storage proteins uique to bacteria, are spherical and hollow proteins that assemble from 24 identical subunits and 12 hemes. This talk will summarize our unique results demonstrating that (1) the function of bacterioferritin (BfrB) is required for P. aeruginosa growth under iron restricted conditions, (2) the function of BfrB in bacterial iron homeostasis requires binding and electron delivery by a cognate ferredoxin, Bfd, (3) the crucial BfrB/Bfd interface, defined by our X-ray crystallographic work, is highly complementary and likely conserved in a number of pathogens, and (4) blocking the BfrB/Bfd interaction leads to altered iron homeostasis, lowers P. aeruginosa fitness and exposes a bacterial vulnerability that may have significance in future development of novel antibiotics.