Structural highlights
Function
[TONB_ECOLI] Interacts with outer membrane receptor proteins that carry out high-affinity binding and energy dependent uptake into the periplasmic space of specific substrates such as cobalamin, and various iron compounds (such as iron dicitrate, enterochelin, aerobactin, etc.). In the absence of TonB these receptors bind their substrates but do not carry out active transport. TonB also interacts with some colicins and is involved in the energy-dependent, irreversible steps of bacteriophages phi 80 and T1 infection. It could act to transduce energy from the cytoplasmic membrane to specific energy-requiring processes in the outer membrane, resulting in the release into the periplasm of ligands bound by these outer membrane proteins.
Evolutionary Conservation
Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf.
Publication Abstract from PubMed
FhuA belongs to a family of specific siderophore transport systems located in the outer membrane of Escherichia coli. The energy required for the transport process is provided by the proton motive force of the cytoplasmic membrane and is transmitted to FhuA by the protein TonB. Although the structure of full-length TonB is not known, the structure of the last 77 residues of a fragment composed of the 86 C-terminal amino acids was recently solved and shows an intertwined dimer (Chang, C., Mooser, A., Pluckthun, A., and Wlodawer, A. (2001) J. Biol. Chem. 276, 27535-27540). We analyzed the ability of truncated C-terminal TonB fragments of different lengths (77, 86, 96, 106, 116, and 126 amino acid residues, respectively) to bind to the receptor FhuA. Only the shortest TonB fragment, TonB-77, could not effectively interact with FhuA. We have also observed that the fragments TonB-77 and TonB-86 form homodimers in solution, whereas the longer fragments remain monomeric. TonB fragments that bind to FhuA in vitro also inhibit ferrichrome uptake via FhuA in vivo and protect cells against attack by bacteriophage Phi80.
Dimerization of TonB is not essential for its binding to the outer membrane siderophore receptor FhuA of Escherichia coli.,Koedding J, Howard P, Kaufmann L, Polzer P, Lustig A, Welte W J Biol Chem. 2004 Mar 12;279(11):9978-86. Epub 2003 Dec 8. PMID:14665631[1]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
See Also
References
- ↑ Koedding J, Howard P, Kaufmann L, Polzer P, Lustig A, Welte W. Dimerization of TonB is not essential for its binding to the outer membrane siderophore receptor FhuA of Escherichia coli. J Biol Chem. 2004 Mar 12;279(11):9978-86. Epub 2003 Dec 8. PMID:14665631 doi:10.1074/jbc.M311720200
