TolB
TolB has been shown to be essential for the function of the Tol system in Escherichia coli[1] by generating an allosteric signal based on a conformational switch in the β-propeller region.
StructureStructure
TolB is a 44-kDa periplasmic protein associated with the outer membrane. It has two domains: an N-terminal α/β domain and a C-terminal six-bladed β-propeller (to which Pal and Colicin E9 bind) [2]. The β-propeller has a latching or ‘Velco’ strand which joins the first and last of the six blades, and is positioned in the domain-domain interface. When Pal binds to the C-terminus of TolB, the latching strand moves away from the interface and carries with it a proline residue. The movement of the latching strand opens up a canyon that would normally be buried between the N- and C-terminal domains of TolB. This canyon can now be used as a binding site for the N-terminal of TolB, which forms a helical half-turn and a β-sheet against the canyon.
TolB forms a complex with Pal ('see below') which plays a role in maintaining the integrity of the outer membrane.
FunctionFunction
The distal N-terminal 12 residues of TolB has two conformational states which are governed by protein-protein interactions with the β -propeller and results in the binding of TolA in the inner membrane.
The TolB-Pal ComplexThe TolB-Pal Complex
| |||||||||
| 2hqs, resolution 1.50Å () | |||||||||
|---|---|---|---|---|---|---|---|---|---|
| Ligands: | , , | ||||||||
| Gene: | tolB (Escherichia coli), pal, excC (Escherichia coli) | ||||||||
| Related: | 1c5k, 1oap, 1crz | ||||||||
| |||||||||
| |||||||||
| Resources: | FirstGlance, OCA, RCSB, PDBsum | ||||||||
| Coordinates: | save as pdb, mmCIF, xml | ||||||||
The TolB-Pal complex is involved in maintaining the outer membrane integrity. This complex is parasitised by protein antibiotics and disrupted in order to trigger the translocation of the toxin across the outer membrane (see Colicin for further information).[3]
Related Tol entriesRelated Tol entries
ReferencesReferences
- ↑ Bonsor DA, Hecht O, Vankemmelbeke M, Sharma A, Krachler AM, Housden NG, Lilly KJ, James R, Moore GR, Kleanthous C. Allosteric beta-propeller signalling in TolB and its manipulation by translocating colicins. EMBO J. 2009 Sep 16;28(18):2846-57. Epub 2009 Aug 20. PMID:19696740 doi:10.1038/emboj.2009.224
- ↑ Bonsor DA, Hecht O, Vankemmelbeke M, Sharma A, Krachler AM, Housden NG, Lilly KJ, James R, Moore GR, Kleanthous C. Allosteric beta-propeller signalling in TolB and its manipulation by translocating colicins. EMBO J. 2009 Sep 16;28(18):2846-57. Epub 2009 Aug 20. PMID:19696740 doi:10.1038/emboj.2009.224
- ↑ Bonsor DA, Grishkovskaya I, Dodson EJ, Kleanthous C. Molecular mimicry enables competitive recruitment by a natively disordered protein. J Am Chem Soc. 2007 Apr 18;129(15):4800-7. Epub 2007 Mar 22. PMID:17375930 doi:http://dx.doi.org/10.1021/ja070153n