Download MendeleySiderophore-mediated iron transport: crystal structure of FhuA with bound lipopolysaccharide.
Ferguson, A.D., Hofmann, E., Coulton, J.W., Diederichs, K., Welte, W.(1998) Science 282: 2215-2220
- PubMed: 9856937
- DOI: https://doi.org/10.1126/science.282.5397.2215
- Primary Citation of Related Structures:
1FCP, 2FCP - PubMed 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.
Organizational Affiliation:
Department of Microbiology and Immunology, McGill University, 3775 University Street, Montreal, Quebec, Canada H3A 2B4.
