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| - | [[Image:1tqq.jpg|left|200px]]<br /><applet load="1tqq" size="450" color="white" frame="true" align="right" spinBox="true" | |
| - | caption="1tqq, resolution 2.75Å" /> | |
| - | '''Structure of TolC in complex with hexamminecobalt'''<br /> | |
| | | | |
| - | ==Overview== | + | ==Structure of TolC in complex with hexamminecobalt== |
| - | The trimeric TolC protein of Escherichia coli comprises an outer membrane, beta-barrel and a contiguous alpha-helical barrel projecting across the, periplasm. This provides a single 140 A long pore for multidrug efflux and, protein export. We have previously reported that trivalent cations such as, hexammine cobalt can severely inhibit the conductivity of the TolC pore, reconstituted in planar lipid bilayers. Here, isothermal calorimetry shows, that Co(NH(3))(6)(3+) binds to TolC with an affinity of 20 nM. The crystal, structure of the TolC-Co(NH(3))(6)(3+) complex was determined to 2.75 A, resolution, and showed no significant difference in the protein when, compared with unliganded TolC. An electron density difference map revealed, that a single ligand molecule binds at the centre of the periplasmic, entrance, the sole constriction of TolC. The octahedral symmetry of the, ligand and the three-fold rotational symmetry of the TolC entrance, determine a binding site in which the ligand forms hydrogen bonds with the, Asp(374) residue of each monomer. When Asp(374) was substituted by, alanine, high affinity ligand binding was abolished and inhibition of TolC, pore conductivity in lipid bilayers was alleviated. Comparable effects, followed independent substitution of the neighbouring Asp(371), indicating, that this aspartate ring also contributes to the high affinity ligand, binding site. As the electronegative entrance is widely conserved in the, TolC family, it may be a useful target for the development of inhibitors, against multidrug resistant pathogenic bacteria. | + | <StructureSection load='1tqq' size='340' side='right'caption='[[1tqq]], [[Resolution|resolution]] 2.75Å' scene=''> |
| | + | == Structural highlights == |
| | + | <table><tr><td colspan='2'>[[1tqq]] is a 3 chain structure with sequence from [https://en.wikipedia.org/wiki/Escherichia_coli Escherichia coli]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1TQQ OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=1TQQ FirstGlance]. <br> |
| | + | </td></tr><tr id='method'><td class="sblockLbl"><b>[[Empirical_models|Method:]]</b></td><td class="sblockDat" id="methodDat">X-ray diffraction, [[Resolution|Resolution]] 2.75Å</td></tr> |
| | + | <tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat" id="ligandDat"><scene name='pdbligand=NCO:COBALT+HEXAMMINE(III)'>NCO</scene></td></tr> |
| | + | <tr id='resources'><td class="sblockLbl"><b>Resources:</b></td><td class="sblockDat"><span class='plainlinks'>[https://proteopedia.org/fgij/fg.htm?mol=1tqq FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=1tqq OCA], [https://pdbe.org/1tqq PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=1tqq RCSB], [https://www.ebi.ac.uk/pdbsum/1tqq PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=1tqq ProSAT]</span></td></tr> |
| | + | </table> |
| | + | == Function == |
| | + | [https://www.uniprot.org/uniprot/TOLC_ECOLI TOLC_ECOLI] Outer membrane channel, which is required for the function of several efflux systems such as AcrAB-TolC, AcrEF-TolC, EmrAB-TolC and MacAB-TolC. These systems are involved in export of antibiotics and other toxic compounds from the cell. TolC is also involved in import of colicin E1 into the cells.<ref>PMID:6337123</ref> <ref>PMID:11274125</ref> <ref>PMID:15228545</ref> <ref>PMID:18955484</ref> <ref>PMID:23176499</ref> |
| | + | == Evolutionary Conservation == |
| | + | [[Image:Consurf_key_small.gif|200px|right]] |
| | + | Check<jmol> |
| | + | <jmolCheckbox> |
| | + | <scriptWhenChecked>; select protein; define ~consurf_to_do selected; consurf_initial_scene = true; script "/wiki/ConSurf/tq/1tqq_consurf.spt"</scriptWhenChecked> |
| | + | <scriptWhenUnchecked>script /wiki/extensions/Proteopedia/spt/initialview01.spt</scriptWhenUnchecked> |
| | + | <text>to colour the structure by Evolutionary Conservation</text> |
| | + | </jmolCheckbox> |
| | + | </jmol>, as determined by [http://consurfdb.tau.ac.il/ ConSurfDB]. You may read the [[Conservation%2C_Evolutionary|explanation]] of the method and the full data available from [http://bental.tau.ac.il/new_ConSurfDB/main_output.php?pdb_ID=1tqq ConSurf]. |
| | + | <div style="clear:both"></div> |
| | + | <div style="background-color:#fffaf0;"> |
| | + | == Publication Abstract from PubMed == |
| | + | The trimeric TolC protein of Escherichia coli comprises an outer membrane beta-barrel and a contiguous alpha-helical barrel projecting across the periplasm. This provides a single 140 A long pore for multidrug efflux and protein export. We have previously reported that trivalent cations such as hexammine cobalt can severely inhibit the conductivity of the TolC pore reconstituted in planar lipid bilayers. Here, isothermal calorimetry shows that Co(NH(3))(6)(3+) binds to TolC with an affinity of 20 nM. The crystal structure of the TolC-Co(NH(3))(6)(3+) complex was determined to 2.75 A resolution, and showed no significant difference in the protein when compared with unliganded TolC. An electron density difference map revealed that a single ligand molecule binds at the centre of the periplasmic entrance, the sole constriction of TolC. The octahedral symmetry of the ligand and the three-fold rotational symmetry of the TolC entrance determine a binding site in which the ligand forms hydrogen bonds with the Asp(374) residue of each monomer. When Asp(374) was substituted by alanine, high affinity ligand binding was abolished and inhibition of TolC pore conductivity in lipid bilayers was alleviated. Comparable effects followed independent substitution of the neighbouring Asp(371), indicating that this aspartate ring also contributes to the high affinity ligand binding site. As the electronegative entrance is widely conserved in the TolC family, it may be a useful target for the development of inhibitors against multidrug resistant pathogenic bacteria. |
| | | | |
| - | ==About this Structure==
| + | Structure of the ligand-blocked periplasmic entrance of the bacterial multidrug efflux protein TolC.,Higgins MK, Eswaran J, Edwards P, Schertler GF, Hughes C, Koronakis V J Mol Biol. 2004 Sep 17;342(3):697-702. PMID:15342230<ref>PMID:15342230</ref> |
| - | 1TQQ is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Escherichia_coli Escherichia coli] with NCO as [http://en.wikipedia.org/wiki/ligand ligand]. Full crystallographic information is available from [http://ispc.weizmann.ac.il/oca-bin/ocashort?id=1TQQ OCA].
| + | |
| | | | |
| - | ==Reference==
| + | From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.<br> |
| - | Structure of the ligand-blocked periplasmic entrance of the bacterial multidrug efflux protein TolC., Higgins MK, Eswaran J, Edwards P, Schertler GF, Hughes C, Koronakis V, J Mol Biol. 2004 Sep 17;342(3):697-702. PMID:[http://ispc.weizmann.ac.il//pmbin/getpm?pmid=15342230 15342230]
| + | </div> |
| | + | <div class="pdbe-citations 1tqq" style="background-color:#fffaf0;"></div> |
| | + | == References == |
| | + | <references/> |
| | + | __TOC__ |
| | + | </StructureSection> |
| | [[Category: Escherichia coli]] | | [[Category: Escherichia coli]] |
| - | [[Category: Single protein]] | + | [[Category: Large Structures]] |
| - | [[Category: Edwards, P.C.]] | + | [[Category: Edwards PC]] |
| - | [[Category: Eswaran, J.]] | + | [[Category: Eswaran J]] |
| - | [[Category: Higgins, M.K.]] | + | [[Category: Higgins MK]] |
| - | [[Category: Hughes, C.]] | + | [[Category: Hughes C]] |
| - | [[Category: Koronakis, V.]] | + | [[Category: Koronakis V]] |
| - | [[Category: Schertler, G.F.]] | + | [[Category: Schertler GF]] |
| - | [[Category: NCO]]
| + | |
| - | [[Category: alpha-barrel]]
| + | |
| - | [[Category: beta-barrel]]
| + | |
| - | | + | |
| - | ''Page seeded by [http://ispc.weizmann.ac.il/oca OCA ] on Wed Nov 21 03:31:04 2007''
| + | |
| Structural highlights
Function
TOLC_ECOLI Outer membrane channel, which is required for the function of several efflux systems such as AcrAB-TolC, AcrEF-TolC, EmrAB-TolC and MacAB-TolC. These systems are involved in export of antibiotics and other toxic compounds from the cell. TolC is also involved in import of colicin E1 into the cells.[1] [2] [3] [4] [5]
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
The trimeric TolC protein of Escherichia coli comprises an outer membrane beta-barrel and a contiguous alpha-helical barrel projecting across the periplasm. This provides a single 140 A long pore for multidrug efflux and protein export. We have previously reported that trivalent cations such as hexammine cobalt can severely inhibit the conductivity of the TolC pore reconstituted in planar lipid bilayers. Here, isothermal calorimetry shows that Co(NH(3))(6)(3+) binds to TolC with an affinity of 20 nM. The crystal structure of the TolC-Co(NH(3))(6)(3+) complex was determined to 2.75 A resolution, and showed no significant difference in the protein when compared with unliganded TolC. An electron density difference map revealed that a single ligand molecule binds at the centre of the periplasmic entrance, the sole constriction of TolC. The octahedral symmetry of the ligand and the three-fold rotational symmetry of the TolC entrance determine a binding site in which the ligand forms hydrogen bonds with the Asp(374) residue of each monomer. When Asp(374) was substituted by alanine, high affinity ligand binding was abolished and inhibition of TolC pore conductivity in lipid bilayers was alleviated. Comparable effects followed independent substitution of the neighbouring Asp(371), indicating that this aspartate ring also contributes to the high affinity ligand binding site. As the electronegative entrance is widely conserved in the TolC family, it may be a useful target for the development of inhibitors against multidrug resistant pathogenic bacteria.
Structure of the ligand-blocked periplasmic entrance of the bacterial multidrug efflux protein TolC.,Higgins MK, Eswaran J, Edwards P, Schertler GF, Hughes C, Koronakis V J Mol Biol. 2004 Sep 17;342(3):697-702. PMID:15342230[6]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
References
- ↑ Morona R, Manning PA, Reeves P. Identification and characterization of the TolC protein, an outer membrane protein from Escherichia coli. J Bacteriol. 1983 Feb;153(2):693-9. PMID:6337123
- ↑ Kobayashi K, Tsukagoshi N, Aono R. Suppression of hypersensitivity of Escherichia coli acrB mutant to organic solvents by integrational activation of the acrEF operon with the IS1 or IS2 element. J Bacteriol. 2001 Apr;183(8):2646-53. PMID:11274125 doi:http://dx.doi.org/10.1128/JB.183.8.2646-2653.2001
- ↑ Touze T, Eswaran J, Bokma E, Koronakis E, Hughes C, Koronakis V. Interactions underlying assembly of the Escherichia coli AcrAB-TolC multidrug efflux system. Mol Microbiol. 2004 Jul;53(2):697-706. PMID:15228545 doi:http://dx.doi.org/10.1111/j.1365-2958.2004.04158.x
- ↑ Lin HT, Bavro VN, Barrera NP, Frankish HM, Velamakanni S, van Veen HW, Robinson CV, Borges-Walmsley MI, Walmsley AR. MacB ABC transporter is a dimer whose ATPase activity and macrolide-binding capacity are regulated by the membrane fusion protein MacA. J Biol Chem. 2009 Jan 9;284(2):1145-54. doi: 10.1074/jbc.M806964200. Epub 2008, Oct 27. PMID:18955484 doi:http://dx.doi.org/10.1074/jbc.M806964200
- ↑ Zakharov SD, Sharma O, Zhalnina M, Yamashita E, Cramer WA. Pathways of colicin import: utilization of BtuB, OmpF porin and the TolC drug-export protein. Biochem Soc Trans. 2012 Dec 1;40(6):1463-8. doi: 10.1042/BST20120211. PMID:23176499 doi:http://dx.doi.org/10.1042/BST20120211
- ↑ Higgins MK, Eswaran J, Edwards P, Schertler GF, Hughes C, Koronakis V. Structure of the ligand-blocked periplasmic entrance of the bacterial multidrug efflux protein TolC. J Mol Biol. 2004 Sep 17;342(3):697-702. PMID:15342230 doi:10.1016/j.jmb.2004.07.088
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