5aym | pdb_00005aym
Crystal structure of a bacterial homologue of iron transporter ferroportin in outward-facing state with soaked iron
Structural highlights
FunctionFPN_BDEBA Iron transpoter that exports Fe(2+) from the cell. Also binds to Co(2+) and Ni(2+). May act as a multivalent divalent metal transporter (PubMed:26608034). The transporter is composed of 12 transmembrane (TM) helices organized into N-terminal (TM1-6) and C-terminal (TM7-12) domains. The substrate-binding site is formed at the interface of the two domains and is alternately accessible from either side of the membrane. The transport cycle is viewed as a series of ligand-induced conformational changes that include open outward and open inward states (PubMed:26461048, PubMed:30082682).[1] [2] [3] Publication Abstract from PubMedIn vertebrates, the iron exporter ferroportin releases Fe(2+) from cells into plasma, thereby maintaining iron homeostasis. The transport activity of ferroportin is suppressed by the peptide hormone hepcidin, which exhibits upregulated expression in chronic inflammation, causing iron-restrictive anaemia. However, due to the lack of structural information about ferroportin, the mechanisms of its iron transport and hepcidin-mediated regulation remain largely elusive. Here we report the crystal structures of a putative bacterial homologue of ferroportin, BbFPN, in both the outward- and inward-facing states. Despite undetectable sequence similarity, BbFPN adopts the major facilitator superfamily fold. A comparison of the two structures reveals that BbFPN undergoes an intra-domain conformational rearrangement during the transport cycle. We identify a substrate metal-binding site, based on structural and mutational analyses. Furthermore, the BbFPN structures suggest that a predicted hepcidin-binding site of ferroportin is located within its central cavity. Thus, BbFPN may be a valuable structural model for iron homeostasis regulation by ferroportin. Outward- and inward-facing structures of a putative bacterial transition-metal transporter with homology to ferroportin.,Taniguchi R, Kato HE, Font J, Deshpande CN, Wada M, Ito K, Ishitani R, Jormakka M, Nureki O Nat Commun. 2015 Oct 13;6:8545. doi: 10.1038/ncomms9545. PMID:26461048[4] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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