1u07
|
Crystal Structure of the 92-residue C-term. part of TonB with significant structural changes compared to shorter fragments
OverviewOverview
Uptake of siderophores and vitamin B(12) through the outer membrane of, Escherichia coli is effected by an active transport system consisting of, several outer membrane receptors and a protein complex of the inner, membrane. The link between these is TonB, a protein associated with the, cytoplasmic membrane, which forms a large periplasmic domain capable of, interacting with several outer membrane receptors, e.g. FhuA, FecA, and, FepA for siderophores and BtuB for vitamin B(12.) The active transport, across the outer membrane is driven by the chemiosmotic gradient of the, inner membrane and is mediated by the TonB protein. The receptor-binding, domain of TonB appears to be formed by a highly conserved C-terminal amino, acid sequence of approximately 100 residues. Crystal structures of two, C-terminal TonB fragments composed of 85 (TonB-85) and 77 (TonB-77) amino, acid residues, respectively, have been previously determined (Chang, C., Mooser, A., Pluckthun, A., and Wlodawer, A. (2001) J. Biol. Chem. 276, 27535-27540 and Koedding, J., Howard, S. P., Kaufmann, L., Polzer, P., Lustig, A., and Welte, W. (2004) J. Biol. Chem. 279, 9978-9986). In both, cases the TonB fragments form dimers in solution and crystallize as dimers, consisting of monomers tightly engaged with one another by the exchange of, a beta-hairpin and a C-terminal beta-strand. Here we present the crystal, structure of a 92-residue fragment of TonB (TonB-92), which is monomeric, in solution. The structure, determined at 1.13-A resolution, shows a dimer, with considerably reduced intermolecular interaction compared with the, other known TonB structures, in particular lacking the beta-hairpin, exchange.
About this StructureAbout this Structure
1U07 is a Single protein structure of sequence from Escherichia coli. Full crystallographic information is available from OCA.
ReferenceReference
Crystal structure of a 92-residue C-terminal fragment of TonB from Escherichia coli reveals significant conformational changes compared to structures of smaller TonB fragments., Kodding J, Killig F, Polzer P, Howard SP, Diederichs K, Welte W, J Biol Chem. 2005 Jan 28;280(4):3022-8. Epub 2004 Nov 2. PMID:15522863
Page seeded by OCA on Wed Nov 21 03:44:25 2007