6bpn
The crystal structure of the Ferric-Catecholate import receptor Fiu from E. coli K12: Open form (C2221)
Structural highlights
FunctionFIU_ECOLI Involved in the active transport across the outer membrane of iron complexed with catecholate siderophores such as dihydroxybenzoylserine and dihydroxybenzoate. It derives its energy for transport by interacting with the trans-periplasmic membrane protein TonB. Can also transport catechol-substituted cephalosporins. Receptor for microcins M, H47 and E492.[1] [2] [3] [4] [5] Publication Abstract from PubMedThe ferric iron uptake (Fiu) transporter from Escherichia coli functions in the transport of iron-catecholate complexes across the bacterial outer membrane, providing the bacterium with iron, which is essential for growth. Recently, it has become clear that Fiu also represents a liability for E. coli because its activity allows the import of antimicrobial compounds that mimic catecholate. This inadvertent import suggests the potential utility of antimicrobial catechol-siderophore mimetics in managing bacterial infections. However, in order to fully exploit these compounds, a detailed understanding of the mechanism of transport through Fiu and related transporters is required. To address this question, we determined the crystal structure of Fiu at 2.1-2.9 A and analyzed its function in E. coli. Through analysis of the Fiu crystal structure, in combination with in silico docking and mutagenesis, we provide insight into how Fiu and related transporters bind catecholate in a surface-exposed cavity. Moreover, through the determination of the structure of Fiu in multiple crystal states, we revealed the presence of a large, selectively-gated cavity in the interior of this transporter. This chamber is large enough to accommodate the Fiu substrate and may allow for the import of substrates via a two-step mechanism. This would avoid channel formation through the transporter and the inadvertent import of toxic molecules. As Fiu and its homologs are the targets of substrate-mimicking antibiotics, these results may assist in the development of these compounds. The structure of the bacterial iron-catecholate transporter Fiu suggests that it imports substrates via a two-step mechanism.,Grinter R, Lithgow T J Biol Chem. 2019 Nov 11. pii: RA119.011018. doi: 10.1074/jbc.RA119.011018. PMID:31712312[6] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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