Publication Date:
1998-12-18
Description:
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.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Ferguson, A D -- Hofmann, E -- Coulton, J W -- Diederichs, K -- Welte, W -- New York, N.Y. -- Science. 1998 Dec 18;282(5397):2215-20.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Microbiology and Immunology, McGill University, 3775 University Street, Montreal, Quebec, Canada H3A 2B4.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/9856937" target="_blank"〉PubMed〈/a〉
Keywords:
Bacterial Outer Membrane Proteins/*chemistry/metabolism
;
Bacterial Proteins/chemistry/metabolism
;
Binding Sites
;
Biological Transport, Active
;
Cell Membrane/chemistry/metabolism
;
Crystallography, X-Ray
;
Diffusion
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Escherichia coli/*chemistry/metabolism
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*Escherichia coli Proteins
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Ferric Compounds/*metabolism
;
Ferrichrome/*metabolism
;
Hydrogen Bonding
;
Ligands
;
Lipopolysaccharides/*metabolism
;
Membrane Proteins/chemistry/metabolism
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Models, Molecular
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*Protein Conformation
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Protein Structure, Secondary
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Receptors, Virus/*chemistry/metabolism
;
Signal Transduction
Print ISSN:
0036-8075
Electronic ISSN:
1095-9203
Topics:
Biology
,
Chemistry and Pharmacology
,
Computer Science
,
Medicine
,
Natural Sciences in General
,
Physics
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