| Structural highlights
2xmn is a 3 chain structure with sequence from Escherichia coli. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance.
| | Ligands: | , |
| Related: | 1ek9, 2vde, 1tqq, 2vdd, 2wmz |
| Resources: | FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT |
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]
Publication Abstract from PubMed
In bacterial drug resistance and virulence pumps, an inner membrane (IM) transporter and periplasmic adaptor recruit an outer membrane (OM) trimeric TolC exit duct that projects an alpha-helical tunnel across the periplasm. The TolC periplasmic entrance is closed by densely packed alpha-helical coiled coils, inner H7/H8, and outer H3/H4, constrained by a hydrogen bond network. On recruitment, these coiled coils must undergo transition to the open state. We present 2.9 A resolution crystal structures of two sequential TolC open states in which the network is incrementally disrupted and channel conductances defined in lipid bilayers. Superimposition of TolC(RS) (370 pS) and TolC(YFRS) (1,000 pS) on the TolC(WT) closed state (80 pS) showed that in the initial open-state TolC(RS), relaxation already causes approximately 14 degrees twisting and expansion of helix H7 at the periplasmic tip, increasing interprotomer distances from 12.2 A in TolC(WT) to 18.9 A. However, in the crystal structure, the weakened Asp(374) pore constriction was maintained at the closed state 11.3 A(2). In the advanced open-state TolC(YFRS), there was little further expansion at the tip, to interprotomer 21.3 A, but substantial movement of inner and outer coiled coils dilated the pore constriction. In particular, upon abolition of the TolC(YFRS) intraprotomer Tyr(362)-Asp(153) link, a redirection of Tyr(362) and "bulge" in H3 allowed a simple movement outward of H8, establishing a 50.3 A(2) opening. Root mean square deviations (rmsds) over the coiled coils of the three protomers of TolC(RS) and TolC(YFRS) illustrate that, whereas independent movement at the periplasmic tips may feature in the initial stages of opening, full dilation of the pore constriction is entirely symmetrical.
Structures of sequential open states in a symmetrical opening transition of the TolC exit duct.,Pei XY, Hinchliffe P, Symmons MF, Koronakis E, Benz R, Hughes C, Koronakis V Proc Natl Acad Sci U S A. 2011 Jan 18. PMID:21245342[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
- ↑ Pei XY, Hinchliffe P, Symmons MF, Koronakis E, Benz R, Hughes C, Koronakis V. Structures of sequential open states in a symmetrical opening transition of the TolC exit duct. Proc Natl Acad Sci U S A. 2011 Jan 18. PMID:21245342 doi:10.1073/pnas.1012588108
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