PMID:9856937
| Citation |
Ferguson, AD, Hofmann, E, Coulton, JW, Diederichs, K and Welte, W (1998) Siderophore-mediated iron transport: crystal structure of FhuA with bound lipopolysaccharide. Science 282:2215-20 |
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| Abstract |
FhuA, the receptor for ferrichrome-iron in Escherichia coli, is a member of a family of integral outer membrane proteins, which, together with the energy-transducing protein TonB, mediate the active transport of ferric siderophores across the outer membrane of Gram-negative bacteria. The three-dimensional structure of FhuA is presented here in two conformations: with and without ferrichrome-iron at resolutions of 2.7 and 2.5 angstroms, respectively. FhuA is a beta barrel composed of 22 antiparallel beta strands. In contrast to the typical trimeric arrangement found in porins, FhuA is monomeric. Located within the beta barrel is a structurally distinct domain, the "cork," which mainly consists of a four-stranded beta sheet and four short alpha helices. A single lipopolysaccharide molecule is noncovalently associated with the membrane-embedded region of the protein. Upon binding of ferrichrome-iron, conformational changes are transduced to the periplasmic pocket of FhuA, signaling the ligand-loaded status of the receptor. Sequence homologies and mutagenesis data are used to propose a structural mechanism for TonB-dependent siderophore-mediated transport across the outer membrane. |
| Links | |
| Keywords |
Bacterial Outer Membrane Proteins/chemistry; Bacterial Outer Membrane Proteins/metabolism; Bacterial Proteins/chemistry; Bacterial Proteins/metabolism; Binding Sites; Biological Transport, Active; Cell Membrane/chemistry; Cell Membrane/metabolism; Crystallography, X-Ray; Diffusion; Escherichia coli/chemistry; Escherichia coli/metabolism; Escherichia coli Proteins; Ferric Compounds/metabolism; Ferrichrome/metabolism; Hydrogen Bonding; Ligands; Lipopolysaccharides/metabolism; Membrane Proteins/chemistry; Membrane Proteins/metabolism; Models, Molecular; Protein Conformation; Protein Structure, Secondary; Receptors, Virus/chemistry; Receptors, Virus/metabolism; Signal Transduction |
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