Download MendeleyCrystal structure of the outer membrane active transporter FepA from Escherichia coli.
Buchanan, S.K., Smith, B.S., Venkatramani, L., Xia, D., Esser, L., Palnitkar, M., Chakraborty, R., van der Helm, D., Deisenhofer, J.(1999) Nat Struct Biol 6: 56-63
- PubMed: 9886293
- DOI: https://doi.org/10.1038/4931
- Primary Citation of Related Structures:
1FEP - PubMed 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.
Organizational Affiliation:
Howard Hughes Medical Institute, and Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas 75235-9050, USA.
