4e6k | pdb_00004e6k
2.0 A resolution structure of Pseudomonas aeruginosa bacterioferritin (BfrB) in complex with bacterioferritin associated ferredoxin (Bfd)
Structural highlights
FunctionBFRB_PSEAE The major iron-storage protein, part of the heterooligomeric bacterioferritin (BFR) complex. The ferroxidase center binds Fe(2+), oxidizes it using dioxygen to Fe(3+), and participates in the subsequent Fe(3+) oxide mineral core formation within the central cavity of the BFR protein shell. Can store up to 600 iron atoms per bacterioferritin protein molecule (PubMed:19575528, PubMed:20067302, PubMed:25640193, PubMed:26368531). In iron-sufficient conditions (10 uM Fe(2+)) iron accumulates in BFR until about 12 hours, when it starts to deplete; stored iron is no longer detectable by 24 hours growth, iron is mobilized from the BFR as levels drop in the growth media (PubMed:28318006). Iron release from the BFR requires ferredoxin NADP reductase (FPR) and bacterioferritin-associated ferredoxin (Bfd) (PubMed:19575528, PubMed:22812654, PubMed:26368531). Reduction of the BfrB heme group occurs in the presence of Bfd, strongly suggesting that the BfrB-Bfd complex allows heme to mediate electron transfer from FPR to the Fe(3+) iron core in the BFR shell prior to its release as Fe(2+) (PubMed:19575528, PubMed:22812654, PubMed:26368531).[1] [2] [3] [4] [5] [6] Publication Abstract from PubMedFerritin-like molecules are unique to cellular iron homeostasis because they can store iron at concentrations much higher than those dictated by the solubility of Fe(3+). Very little is known about the protein interactions that deliver iron for storage, or promote the mobilization of stored iron from ferritin-like molecules. Here, we report the X-ray crystal structure of Pseudomonas aeruginosa bacterioferritin (Pa-BfrB) in complex with bacterioferritin-associated ferredoxin (Pa-Bfd) at 2.0 A resolution. As the first example of a ferritin-like molecule in complex with a cognate partner, the structure provides unprecedented insight into the complementary interface that enables the [2Fe-2S] cluster of Pa-Bfd to promote heme-mediated electron transfer through the BfrB protein dielectric (~18 A), a process that is necessary to reduce the core ferric mineral and facilitate mobilization of Fe(2+). The Pa-BfrB-Bfd complex also revealed the first structure of a Bfd, thus providing a first view to what appears to be a versatile metal binding domain ubiquitous to the large Fer2_BFD family of proteins and enzymes with diverse functions. Residues at the Pa-BfrB-Bfd interface are highly conserved in Bfr and Bfd sequences from a number of pathogenic bacteria, suggesting that the specific recognition between Pa-BfrB and Pa-Bfd is of widespread significance to the understanding of bacterial iron homeostasis. The structure of the BfrB-Bfd complex reveals protein-protein interactions enabling iron release from bacterioferritin.,Yao H, Wang Y, Lovell SW, Kumar R, Ruvinsky AM, Battaile KP, Vakser IA, Rivera M J Am Chem Soc. 2012 Jul 19. PMID:22812654[7] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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