PMID:9886293

Citation	Buchanan, SK, Smith, BS, Venkatramani, L, Xia, D, Esser, L, Palnitkar, M, Chakraborty, R, van der Helm, D and Deisenhofer, J (1999) Crystal structure of the outer membrane active transporter FepA from Escherichia coli. Nat. Struct. Biol. 6:56-63
Abstract	Integral outer membrane receptors for iron chelates and vitamin B12 carry out specific ligand transport against a concentration gradient. Energy for active transport is obtained from the proton-motive force of the inner membrane through physical interaction with TonB-ExbB-ExbD, an inner membrane complex. Here we report the crystal structure of an active transport, outer membrane receptor at 2.4 A resolution. Two distinct functional domains are revealed: (i) a 22-stranded beta-barrel that spans the outer membrane and contains large extracellular loops which appear to function in ligand binding; and (ii) a globular N-terminal domain that folds into the barrel pore, inhibiting access to the periplasm and contributing two additional loops for potential ligand binding. These loops could provide a signaling pathway between the processes of ligand recognition and TonB-mediated transport. The blockage of the pore suggests that the N-terminal domain must undergo a conformational rearrangement to allow ligand transport into the periplasm.
Links	PubMed Online version:10.1038/4931
Keywords	Amino Acid Sequence; Bacterial Outer Membrane Proteins/chemistry; Carrier Proteins/chemistry; Crystallography, X-Ray; Escherichia coli/chemistry; Molecular Sequence Data; Protein Conformation; Receptors, Cell Surface
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Annotations

Gene product	Qualifier	GO Term	Evidence Code	with/from	Aspect	Extension	Notes	Status
ECOLI:FEPA	part_of	GO:0045203: integral component of cell outer membrane	ECO:0000314: direct assay evidence used in manual assertion		C		Seeded From UniProt	complete

References

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