Browse Text search Protein search Domain search Download User manual Related links Citation & Contact


The Outer Membrane Receptor (OMR-TonB Dependent Receptor) Family [Function: Receptor] Seed alignment | Full alignment in OMPdb

This large family consists of receptors found in nearly all classes of Gram-negative bacteria and Cyanobacteria. These outer membrane proteins act as receptors for organic iron chelators (siderophores) and vitamins necessary for bacterial life. Members of this family are also termed TonB-dependent receptors because their action is mediated by the periplasmic domain of TonB protein. A complex of three membrane proteins (TonB, ExbB and ExbD) couples the chemiosmotic potential of the cytoplasmic membrane with siderophore uptake across the outer membrane. The crystallographic structures of several TonB-dependent Receptors (FhuA, FepA, FecA, BtuB, FusA) have recently been determined. These outer membrane receptors show a novel fold consisting of two domains. A 22-stranded antiparallel β-barrel traverses the outer membrane with the adjacent beta-strands being connected by large extracellular loops and periplasmic turns. At the N-terminal there is the Plug domain (of approximately 140 residues in length), located inside the β-barrel, which is composed primarily of a mixed 4-stranded beta sheets and a series of interspersed alpha helices. The Plug domain closes the channel pore and has been shown to interact with both the ligand and the periplasmic components. Ligand binding induces distinct local and allosteric transitions that establish the structural basis of signal transduction across the outer membrane.


Specify pHMMs' % coverageUnspecified More than   
Representative image:  fam_img

Literature references

TonB-dependent receptors-structural perspectives
Biochim Biophys Acta. 2002 Oct 11;1565(2):318-32. doi: 10.1016/s0005-2736(02)00578-3.
PMID: 12409204

Mechanisms of iron acquisition by the human pathogens Neisseria meningitidis and Neisseria gonorrhoeae
Front Biosci. 2003 Sep 1;8:d1186-218. doi: 10.2741/1133.
PMID: 12957813

Binding of iron-free siderophore, a common feature of siderophore outer membrane transporters of Escherichia coli and Pseudomonas aeruginosa
J Biol Chem. 2005 May 27;280(21):20222-30. doi: 10.1074/jbc.M500776200. Epub 2005 Mar 22.
PMID: 15784620

The solution structure of the C-terminal domain of TonB and interaction studies with TonB box peptides
J Mol Biol. 2005 Feb 4;345(5):1185-97. doi: 10.1016/j.jmb.2004.11.026. Epub 2004 Dec 15.
PMID: 15644214

The Escherichia coli outer membrane cobalamin transporter BtuB: structural analysis of calcium and substrate binding, and identification of orthologous transporters by sequence/structure conservation
J Mol Biol. 2003 Oct 3;332(5):999-1014. doi: 10.1016/j.jmb.2003.07.005.
PMID: 14499604

TonB-dependent outer membrane transport: going for Baroque?
Curr Opin Struct Biol. 2005 Aug;15(4):394-400. doi: 10.1016/j.sbi.2005.07.001.
PMID: 16039843

Crystal structure of the outer membrane active transporter FepA from Escherichia coli
Nat Struct Biol. 1999 Jan;6(1):56-63. doi: 10.1038/4931.
PMID: 9886293

Substrate-induced transmembrane signaling in the cobalamin transporter BtuB
Nat Struct Biol. 2003 May;10(5):394-401. doi: 10.1038/nsb914.
PMID: 12652322

In meso structure of the cobalamin transporter, BtuB, at 1.95 A resolution
J Mol Biol. 2006 Dec 8;364(4):716-34. doi: 10.1016/j.jmb.2006.09.022. Epub 2006 Sep 12.
PMID: 17028020

Outer membrane active transport: structure of the BtuB:TonB complex
Science. 2006 Jun 2;312(5778):1396-9. doi: 10.1126/science.1127694.
PMID: 16741124

Structure of the complex of the colicin E2 R-domain and its BtuB receptor. The outer membrane colicin translocon
J Biol Chem. 2007 Aug 10;282(32):23163-70. doi: 10.1074/jbc.M703004200. Epub 2007 Jun 4.
PMID: 17548346

The structure of BtuB with bound colicin E3 R-domain implies a translocon
Nat Struct Biol. 2003 Nov;10(11):948-54. doi: 10.1038/nsb997. Epub 2003 Oct 5.
PMID: 14528295

Transmembrane signaling across the ligand-gated FhuA receptor: crystal structures of free and ferrichrome-bound states reveal allosteric changes
Cell. 1998 Dec 11;95(6):771-8. doi: 10.1016/s0092-8674(00)81700-6.
PMID: 9865695

Siderophore-mediated iron transport: crystal structure of FhuA with bound lipopolysaccharide
Science. 1998 Dec 18;282(5397):2215-20. doi: 10.1126/science.282.5397.2215.
PMID: 9856937

A conserved structural motif for lipopolysaccharide recognition by procaryotic and eucaryotic proteins
Structure. 2000 Jun 15;8(6):585-92. doi: 10.1016/s0969-2126(00)00143-x.
PMID: 10873859

Crystal structure of the antibiotic albomycin in complex with the outer membrane transporter FhuA
Protein Sci. 2000 May;9(5):956-63. doi: 10.1110/ps.9.5.956.
PMID: 10850805

Active transport of an antibiotic rifamycin derivative by the outer-membrane protein FhuA
Structure. 2001 Aug;9(8):707-16. doi: 10.1016/s0969-2126(01)00631-1.
PMID: 11587645

Structure of TonB in complex with FhuA, E. coli outer membrane receptor
Science. 2006 Jun 2;312(5778):1399-402. doi: 10.1126/science.1128057.
PMID: 16741125

Structural basis of gating by the outer membrane transporter FecA
Science. 2002 Mar 1;295(5560):1715-9. doi: 10.1126/science.1067313.
PMID: 11872840

Structural evidence for iron-free citrate and ferric citrate binding to the TonB-dependent outer membrane transporter FecA
J Mol Biol. 2003 Sep 12;332(2):353-68. doi: 10.1016/s0022-2836(03)00855-6.
PMID: 12948487

Nuclear magnetic resonance solution structure of the periplasmic signalling domain of the TonB-dependent outer membrane transporter FecA from Escherichia coli
Mol Microbiol. 2005 Dec;58(5):1226-37. doi: 10.1111/j.1365-2958.2005.04889.x.
PMID: 16313612

Structure of colicin I receptor bound to the R-domain of colicin Ia: implications for protein import
EMBO J. 2007 May 16;26(10):2594-604. doi: 10.1038/sj.emboj.7601693. Epub 2007 Apr 26.
PMID: 17464289

Crystal structure at high resolution of ferric-pyochelin and its membrane receptor FptA from Pseudomonas aeruginosa
J Mol Biol. 2005 Sep 30;352(4):893-904. doi: 10.1016/j.jmb.2005.08.004.
PMID: 16139844

The crystal structure of the pyoverdine outer membrane receptor FpvA from Pseudomonas aeruginosa at 3.6 angstroms resolution
J Mol Biol. 2005 Mar 18;347(1):121-34. doi: 10.1016/j.jmb.2005.01.021. Epub 2005 Jan 21.
PMID: 15733922

A beta strand lock exchange for signal transduction in TonB-dependent transducers on the basis of a common structural motif
Structure. 2007 Nov;15(11):1383-91. doi: 10.1016/j.str.2007.08.013.
PMID: 17997964

Heme uptake across the outer membrane as revealed by crystal structures of the receptor-hemophore complex
Proc Natl Acad Sci U S A. 2009 Jan 27;106(4):1045-50. doi: 10.1073/pnas.0809406106. Epub 2009 Jan 14.
PMID: 19144921

Structure of the bacterial plant-ferredoxin receptor FusA
Nat Commun. 2016 Oct 31;7:13308. doi: 10.1038/ncomms13308.
PMID: 27796364

Proteins in this family with 3D-structure

Q9I116

P16869

Q05098

V6ALN4

P75780

G3XD89

G3XCY8

D0CAH3

P42512

Q9K0U9

P05825

P48632

Q9JZN9

Q79AD2

P46359

Q51162

Q9X6A5

C5I2D9

P17315

P06971

Q841A2

P06129

P72412

P13036

D0C8V9

Q9I527

Q6D8U4


Elixir UTH dib compgen