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Escherichia coli K-12 substr. MG1655 Polypeptide: vitamin B12 / E colicin / bacteriophage BF23 outer membrane porin BtuB
Inferred from experiment




Gene: btuB Accession Numbers: EG10126 (EcoCyc), b3966, ECK3958

Synonyms: bfe, cer

Regulation Summary Diagram

Regulation summary diagram for btuB

Component of:
vitamin B12 outer membrane transport complex
vitamin B12 transport system

Summary:
BtuB is an outer membrane porin (OMP) that mediates binding and TonB-dependent active transport of vitamin B12 (cyanocobalamin) across the outer membrane. The system has a high affinity for vitamin B12 and its many derivatives including adenosylcobalamin and cobinamide [Bradbeer78, Roth96]. Calcium binding to BtuB induces high-affinity binding of cyanocobalamin. Several structures of this 22 strand beta barrel protein have been elucidated including a structure with bound calcium and cyanocobalamin [Chimento03]. The Ton box of BtuB unfolds and extends into the periplasm in the presence of substrate in order to initiate interaction with TonB so that transport can occur [Xu06a].

BtuB is also the receptor for group A colicins which enter by way of the Tol system. OmpF imports the cytotoxic domains of group A colicins E3 and N after the colicins bind to the BtuB receptor [Zakharov04, Zakharov06]. The presence of BtuB has been shown to be necessary for the cleavage of endonuclease colicin E2 (ColE2), and the associated cognate immunity protein (Im2) by OmpT [Duche09]. FRET analyses have shown that free energy for colicin unfolding is provided by binding of the R- domain to BtuB [Zakharov08]. BtuB production decreased in response to exogenous polyamines which are known to provide resistance to ColE7 [Pan06].

The crystal structure of BtuB has also been solved with the bound carboxy terminus of TonB to a resolution of 2.1 Å [Shultis06, Shultis06a], and alone to a resolution of 1.95 Å [Cherezov06].

Translation is down-regulated by coenzyme B(12) via a direct interaction between the compound and the 5'-untranslated region of the mRNA [Nahvi02].

OMP localisation and turnover has been studied using labelled, modified colicin E9 which forms a complex with BtuB but is blocked for import. OMPs cluster in islands which are stabilised by promiscuous protein-protein interactions; OMPs engage in both homologous and heterologous associations that slow their diffusion in the outer membrane. OMP biogenesis is greatest at the mid-cell and diminishes towards the poles [Rassam15].

Citations: [Cadieux03, Likhacheva96, Samsonov02]

Locations: outer membrane

Map Position: [4,161,662 -> 4,163,506] (89.7 centisomes, 323°)
Length: 1845 bp / 614 aa

Molecular Weight of Polypeptide: 68.407 kD (from nucleotide sequence)

Unification Links: ASAP:ABE-0012987, CGSC:946, DIP:DIP-9232N, EchoBASE:EB0124, EcoGene:EG10126, EcoliWiki:b3966, ModBase:P06129, OU-Microarray:b3966, PortEco:btuB, PR:PRO_000022234, Pride:P06129, Protein Model Portal:P06129, RefSeq:NP_418401, RegulonDB:EG10126, SMR:P06129, String:511145.b3966, UniProt:P06129

Relationship Links: InterPro:IN-FAMILY:IPR000531, InterPro:IN-FAMILY:IPR010101, InterPro:IN-FAMILY:IPR010916, InterPro:IN-FAMILY:IPR010917, InterPro:IN-FAMILY:IPR012910, PDB:Structure:1NQE, PDB:Structure:1NQF, PDB:Structure:1NQG, PDB:Structure:1NQH, PDB:Structure:1UJW, PDB:Structure:2GSK, PDB:Structure:2GUF, PDB:Structure:2YSU, PDB:Structure:3M8B, PDB:Structure:3M8D, PDB:Structure:3RGM, PDB:Structure:3RGN, Pfam:IN-FAMILY:PF00593, Pfam:IN-FAMILY:PF07715, Prosite:IN-FAMILY:PS00430, Prosite:IN-FAMILY:PS01156

In Paralogous Gene Group: 51 (8 members)

Gene-Reaction Schematic

Gene-Reaction Schematic

Genetic Regulation Schematic

Genetic regulation schematic for btuB


GO Terms:
Biological Process:
Inferred from experimentInferred by computational analysisGO:0015889 - cobalamin transport [GOA06, GOA01a, Cadieux02]
Inferred by computational analysisGO:0006810 - transport [UniProtGOA11a, GOA01a]
Inferred by computational analysisGO:0006811 - ion transport [UniProtGOA11a]
Inferred by computational analysisGO:0055085 - transmembrane transport [UniProtGOA11a]
Molecular Function:
Inferred by computational analysisGO:0004872 - receptor activity [GOA01a]
Inferred by computational analysisGO:0015235 - cobalamin transporter activity [GOA06, GOA01a]
Inferred by computational analysisGO:0015288 - porin activity [UniProtGOA11a]
Inferred by computational analysisGO:0046872 - metal ion binding [UniProtGOA11a]
Cellular Component:
Inferred by computational analysisGO:0009279 - cell outer membrane [UniProtGOA11, UniProtGOA11a, GOA06]
Inferred by computational analysisGO:0016020 - membrane [UniProtGOA11a, GOA01a]
Inferred by computational analysisGO:0016021 - integral component of membrane [UniProtGOA11a]
Inferred by computational analysisGO:0046930 - pore complex [UniProtGOA11a]

MultiFun Terms: extrachromosomalprophage genes and phage related functions
transportChannel-type TransportersBeta barrel porins (The Outer Membrane Porin (OMP) Functional Superfamily)

Essentiality data for btuB knockouts:

Growth Medium Growth? T (°C) O2 pH Osm/L Growth Observations
LB enrichedYes 37 Aerobic 6.95   Yes [Gerdes03, Comment 1]
LB LennoxNo 37 Aerobic 7   No [Baba06, Yamamoto09]

Subunit of: vitamin B12 outer membrane transport complex

Subunit composition of vitamin B12 outer membrane transport complex = [BtuB][(TonB)(ExbB)(ExbD)]
         vitamin B12 / E colicin / bacteriophage BF23 outer membrane porin BtuB = BtuB (extended summary available)
         TonB energy transducing system = (TonB)(ExbB)(ExbD) (extended summary available)
                 TonB energy transducing system - TonB subunit = TonB (extended summary available)
                 TonB energy transducing system - ExbB subunit = ExbB (summary available)
                 tonB energy transducing system - ExbD subunit = ExbD (summary available)

Component of: vitamin B12 transport system

Locations: outer membrane, inner membrane, periplasmic space


GO Terms:
Cellular Component:
GO:0005886 - plasma membrane []
GO:0009279 - cell outer membrane []
GO:0030288 - outer membrane-bounded periplasmic space []

Enzymatic reaction of: transport of cobinamide (vitamin B12 outer membrane transport complex)

Author statement

Transport reaction diagram for transport of cobinamide


Enzymatic reaction of: transport of cob(I)alamin (vitamin B12 outer membrane transport complex)

Inferred from experiment

Transport reaction diagram for transport of cob(I)alamin

Alternative Products for cob(I)alamin: adenosylcobalamin [Bradbeer78]

Subunit of: vitamin B12 transport system

Subunit composition of vitamin B12 transport system = [(BtuB)([TonB][ExbB][ExbD])][(BtuD)2(BtuC)2(BtuF)]
         vitamin B12 outer membrane transport complex = (BtuB)([TonB][ExbB][ExbD])
                 vitamin B12 / E colicin / bacteriophage BF23 outer membrane porin BtuB = BtuB (extended summary available)
                 TonB energy transducing system = (TonB)(ExbB)(ExbD) (extended summary available)
                         TonB energy transducing system - TonB subunit = TonB (extended summary available)
                         TonB energy transducing system - ExbB subunit = ExbB (summary available)
                         tonB energy transducing system - ExbD subunit = ExbD (summary available)
         vitamin B12 ABC transporter = (BtuD)2(BtuC)2(BtuF) (extended summary available)
                 vitamin B12 ABC transporter - ATP binding subunit = BtuD (summary available)
                 vitamin B12 ABC transporter - membrane subunit = BtuC (summary available)
                 vitamin B12 ABC transporter - periplasmic binding protein = BtuF (summary available)


Enzymatic reaction of: cobinamide transport (vitamin B12 transport system)

Inferred from experiment

Transport reaction diagram for cobinamide transport


Enzymatic reaction of: cob(I)alamin transport (vitamin B12 transport system)

Inferred from experiment

Transport reaction diagram for cob(I)alamin transport

Alternative Products for cob(I)alamin: adenosylcobalamin [Bradbeer78]

Sequence Features

Protein sequence of vitamin B12 / E colicin / bacteriophage BF23 outer membrane porin BtuB with features indicated

Feature Class Location Citations Comment
Signal-Sequence 1 -> 20
Inferred from experiment[Link97]
 
Chain 21 -> 614
Author statement[UniProt15]
UniProt: Vitamin B12 transporter BtuB.
Protein-Segment 26 -> 33
Author statement[UniProt15]
UniProt: TonB box; Sequence Annotation Type: short sequence motif.
Mutagenesis-Variant 28
Inferred from experiment[Coggshall01]
UniProt: Inactivates uptake.
Mutagenesis-Variant 30
Inferred from experiment[Coggshall01]
V → G or P: Inactivates uptake.
Protein-Segment 108 -> 112
Author statement[UniProt15]
UniProt: Cobalamin-binding; Sequence Annotation Type: region of interest.
Transmembrane-Region 158 -> 165
Author statement[UniProt15]
UniProt: Beta stranded.
Sequence-Conflict 162
Inferred by curator[Heller85, UniProt15]
UniProt: (in Ref. 1; AAA23524).
Transmembrane-Region 169 -> 178
Author statement[UniProt15]
UniProt: Beta stranded.
Transmembrane-Region 184 -> 195
Author statement[UniProt15]
UniProt: Beta stranded.
Metal-Binding-Site 199
Author statement[UniProt15]
UniProt: Calcium 1.
Metal-Binding-Site 211
Author statement[UniProt15]
UniProt: Calcium 1.
Metal-Binding-Site 213
Author statement[UniProt15]
UniProt: Calcium 1.
Metal-Binding-Site 215
Author statement[UniProt15]
UniProt: Calcium 1.
Transmembrane-Region 217 -> 227
Author statement[UniProt15]
UniProt: Beta stranded.
Transmembrane-Region 232 -> 248
Author statement[UniProt15]
UniProt: Beta stranded.
Metal-Binding-Site 249
Author statement[UniProt15]
UniProt: Calcium 2; via carbonyl oxygen.
Protein-Segment 249 -> 251
Author statement[UniProt15]
UniProt: Cobalamin-binding; Sequence Annotation Type: region of interest.
Metal-Binding-Site 250
Author statement[UniProt15]
UniProt: Calcium 1.
Metal-Binding-Site 261
Author statement[UniProt15]
UniProt: Calcium 2.
Transmembrane-Region 263 -> 277
Author statement[UniProt15]
UniProt: Beta stranded.
Transmembrane-Region 279 -> 296
Author statement[UniProt15]
UniProt: Beta stranded.
Transmembrane-Region 309 -> 325
Author statement[UniProt15]
UniProt: Beta stranded.
Transmembrane-Region 328 -> 337
Author statement[UniProt15]
UniProt: Beta stranded.
Transmembrane-Region 353 -> 369
Author statement[UniProt15]
UniProt: Beta stranded.
Transmembrane-Region 371 -> 381
Author statement[UniProt15]
UniProt: Beta stranded.
Sequence-Conflict 377
Inferred by curator[Heller85, UniProt15]
UniProt: (in Ref. 1; AAA23524).
Transmembrane-Region 385 -> 400
Author statement[UniProt15]
UniProt: Beta stranded.
Transmembrane-Region 403 -> 417
Author statement[UniProt15]
UniProt: Beta stranded.
Transmembrane-Region 434 -> 443
Author statement[UniProt15]
UniProt: Beta stranded.
Transmembrane-Region 449 -> 458
Author statement[UniProt15]
UniProt: Beta stranded.
Transmembrane-Region 473 -> 490
Author statement[UniProt15]
UniProt: Beta stranded.
Transmembrane-Region 494 -> 509
Author statement[UniProt15]
UniProt: Beta stranded.
Protein-Segment 515 -> 518
Author statement[UniProt15]
UniProt: Cobalamin-binding; Sequence Annotation Type: region of interest.
Transmembrane-Region 517 -> 529
Author statement[UniProt15]
UniProt: Beta stranded.
Transmembrane-Region 535 -> 550
Author statement[UniProt15]
UniProt: Beta stranded.
Transmembrane-Region 558 -> 572
Author statement[UniProt15]
UniProt: Beta stranded.
Transmembrane-Region 585 -> 596
Author statement[UniProt15]
UniProt: Beta stranded.
Protein-Segment 597 -> 614
Author statement[UniProt15]
UniProt: TonB C-terminal box; Sequence Annotation Type: short sequence motif.
Transmembrane-Region 602 -> 614
Author statement[UniProt15]
UniProt: Beta stranded.


Sequence Pfam Features

Protein sequence of vitamin B12 / E colicin / bacteriophage BF23 outer membrane porin BtuB with features indicated

Feature Class Location Citations Comment
Pfam PF07715 41 -> 146
Inferred by computational analysis[Finn14]
Plug : TonB-dependent Receptor Plug Domain
Pfam PF00593 390 -> 613
Inferred by computational analysis[Finn14]
TonB_dep_Rec : TonB dependent receptor


Gene Local Context (not to scale -- see Genome Browser for correct scale)

Gene local context diagram

Transcription Unit

Transcription-unit diagram

Notes:

History:
3/2/1998 (pkarp) Merged genes G276/cer and EG10126/btuB
10/20/97 Gene b3966 from Blattner lab Genbank (v. M52) entry merged into EcoCyc gene EG10126; confirmed by SwissProt match.


References

Baba06: Baba T, Ara T, Hasegawa M, Takai Y, Okumura Y, Baba M, Datsenko KA, Tomita M, Wanner BL, Mori H (2006). "Construction of Escherichia coli K-12 in-frame, single-gene knockout mutants: the Keio collection." Mol Syst Biol 2;2006.0008. PMID: 16738554

Bassford76: Bassford PJ, Bradbeer C, Kadner RJ, Schnaitman CA (1976). "Transport of vitamin B12 in tonB mutants of Escherichia coli." J Bacteriol 128(1);242-7. PMID: 135755

Bradbeer78: Bradbeer C, Kenley JS, Di Masi DR, Leighton M (1978). "Transport of vitamin B12 in Escherichia coli. Corrinoid specificities of the periplasmic B12-binding protein and of energy-dependent B12 transport." J Biol Chem 253(5);1347-52. PMID: 342526

Cadieux02: Cadieux N, Bradbeer C, Reeger-Schneider E, Koster W, Mohanty AK, Wiener MC, Kadner RJ (2002). "Identification of the periplasmic cobalamin-binding protein BtuF of Escherichia coli." J Bacteriol 2002;184(3);706-17. PMID: 11790740

Cadieux03: Cadieux N, Phan PG, Cafiso DS, Kadner RJ (2003). "Differential substrate-induced signaling through the TonB-dependent transporter BtuB." Proc Natl Acad Sci U S A 100(19);10688-93. PMID: 12958215

Cherezov06: Cherezov V, Yamashita E, Liu W, Zhalnina M, Cramer WA, Caffrey M (2006). "In meso structure of the cobalamin transporter, BtuB, at 1.95 A resolution." J Mol Biol 364(4);716-34. PMID: 17028020

Chimento03: Chimento DP, Mohanty AK, Kadner RJ, Wiener MC (2003). "Substrate-induced transmembrane signaling in the cobalamin transporter BtuB." Nat Struct Biol 10(5);394-401. PMID: 12652322

Coggshall01: Coggshall KA, Cadieux N, Piedmont C, Kadner RJ, Cafiso DS (2001). "Transport-defective mutations alter the conformation of the energy-coupling motif of an outer membrane transporter." Biochemistry 40(46);13964-71. PMID: 11705387

Duche09: Duche D, Issouf M, Lloubes R (2009). "Immunity Protein Protects Colicin E2 from OmpT Protease." J Biochem 145(1);95-101. PMID: 18990718

Finn14: Finn RD, Bateman A, Clements J, Coggill P, Eberhardt RY, Eddy SR, Heger A, Hetherington K, Holm L, Mistry J, Sonnhammer EL, Tate J, Punta M (2014). "Pfam: the protein families database." Nucleic Acids Res 42(Database issue);D222-30. PMID: 24288371

Gerdes03: Gerdes SY, Scholle MD, Campbell JW, Balazsi G, Ravasz E, Daugherty MD, Somera AL, Kyrpides NC, Anderson I, Gelfand MS, Bhattacharya A, Kapatral V, D'Souza M, Baev MV, Grechkin Y, Mseeh F, Fonstein MY, Overbeek R, Barabasi AL, Oltvai ZN, Osterman AL (2003). "Experimental determination and system level analysis of essential genes in Escherichia coli MG1655." J Bacteriol 185(19);5673-84. PMID: 13129938

GOA01a: GOA, DDB, FB, MGI, ZFIN (2001). "Gene Ontology annotation through association of InterPro records with GO terms."

GOA06: GOA, SIB (2006). "Electronic Gene Ontology annotations created by transferring manual GO annotations between orthologous microbial proteins."

Heller85: Heller K, Kadner RJ (1985). "Nucleotide sequence of the gene for the vitamin B12 receptor protein in the outer membrane of Escherichia coli." J Bacteriol 161(3);904-8. PMID: 3882670

Kenley78: Kenley JS, Leighton M, Bradbeer C (1978). "Transport of vitamin B12 in Escherichia coli. Corrinoid specificity of the outer membrane receptor." J Biol Chem 253(5);1341-6. PMID: 342525

Likhacheva96: Likhacheva NA, Samsonov VV, Samsonov VV, Sineoky SP (1996). "Genetic control of the resistance to phage C1 of Escherichia coli K-12." J Bacteriol 178(17);5309-15. PMID: 8752353

Link97: Link AJ, Robison K, Church GM (1997). "Comparing the predicted and observed properties of proteins encoded in the genome of Escherichia coli K-12." Electrophoresis 18(8);1259-313. PMID: 9298646

Nahvi02: Nahvi A, Sudarsan N, Ebert MS, Zou X, Brown KL, Breaker RR (2002). "Genetic control by a metabolite binding mRNA." Chem Biol 2002;9(9);1043. PMID: 12323379

Pan06: Pan YH, Liao CC, Kuo CC, Duan KJ, Liang PH, Yuan HS, Hu ST, Chak KF (2006). "The critical roles of polyamines in regulating ColE7 production and restricting ColE7 uptake of the colicin-producing Escherichia coli." J Biol Chem 281(19);13083-91. PMID: 16549429

Rassam15: Rassam P, Copeland NA, Birkholz O, Toth C, Chavent M, Duncan AL, Cross SJ, Housden NG, Kaminska R, Seger U, Quinn DM, Garrod TJ, Sansom MS, Piehler J, Baumann CG, Kleanthous C (2015). "Supramolecular assemblies underpin turnover of outer membrane proteins in bacteria." Nature 523(7560);333-6. PMID: 26061769

Roth96: Roth JR, Lawrence JG, Bobik TA (1996). "Cobalamin (coenzyme B12): synthesis and biological significance." Annu Rev Microbiol 50;137-81. PMID: 8905078

Samsonov02: Samsonov VV, Samsonov VV, Sineoky SP (2002). "DcrA and dcrB Escherichia coli genes can control DNA injection by phages specific for BtuB and FhuA receptors." Res Microbiol 153(10);639-46. PMID: 12558182

Shultis06: Shultis DD, Purdy MD, Banchs CN, Wiener MC (2006). "Outer membrane active transport: structure of the BtuB:TonB complex." Science 312(5778);1396-9. PMID: 16741124

Shultis06a: Shultis DD, Purdy MD, Banchs CN, Wiener MC (2006). "Crystallization and preliminary X-ray crystallographic analysis of the Escherichia coli outer membrane cobalamin transporter BtuB in complex with the carboxy-terminal domain of TonB." Acta Crystallograph Sect F Struct Biol Cryst Commun 62(Pt 7);638-41. PMID: 16820681

UniProt15: UniProt Consortium (2015). "UniProt version 2015-08 released on 2015-07-22." Database.

UniProtGOA11: UniProt-GOA (2011). "Gene Ontology annotation based on the manual assignment of UniProtKB Subcellular Location terms in UniProtKB/Swiss-Prot entries."

UniProtGOA11a: UniProt-GOA (2011). "Gene Ontology annotation based on manual assignment of UniProtKB keywords in UniProtKB/Swiss-Prot entries."

Xu06a: Xu Q, Ellena JF, Kim M, Cafiso DS (2006). "Substrate-dependent unfolding of the energy coupling motif of a membrane transport protein determined by double electron-electron resonance." Biochemistry 45(36);10847-54. PMID: 16953570

Yamamoto09: Yamamoto N, Nakahigashi K, Nakamichi T, Yoshino M, Takai Y, Touda Y, Furubayashi A, Kinjyo S, Dose H, Hasegawa M, Datsenko KA, Nakayashiki T, Tomita M, Wanner BL, Mori H (2009). "Update on the Keio collection of Escherichia coli single-gene deletion mutants." Mol Syst Biol 5;335. PMID: 20029369

Zakharov04: Zakharov SD, Eroukova VY, Rokitskaya TI, Zhalnina MV, Sharma O, Loll PJ, Zgurskaya HI, Antonenko YN, Cramer WA (2004). "Colicin occlusion of OmpF and TolC channels: outer membrane translocons for colicin import." Biophys J 87(6);3901-11. PMID: 15465872

Zakharov06: Zakharov SD, Zhalnina MV, Sharma O, Cramer WA (2006). "The colicin E3 outer membrane translocon: immunity protein release allows interaction of the cytotoxic domain with OmpF porin." Biochemistry 45(34);10199-207. PMID: 16922495

Zakharov08: Zakharov SD, Sharma O, Zhalnina MV, Cramer WA (2008). "Primary Events in the Colicin Translocon: FRET Analysis of Colicin Unfolding Initiated by Binding to BtuB and OmpF." Biochemistry. PMID: 18986168

Other References Related to Gene Regulation

Aufrere86: Aufrere R, Tempete M, Bohin JP (1986). "Regulation of expression of the gene for vitamin B12 receptor cloned on a multicopy plasmid in Escherichia coli." Mol Gen Genet 1986;205(2);358-65. PMID: 3027510

Gallo08: Gallo S, Oberhuber M, Sigel RK, Krautler B (2008). "The Corrin Moiety of Coenzyme B(12) is the Determinant for Switching the btuB Riboswitch of E. coli." Chembiochem 9(9):1408-14. PMID: 18506875

Lei11: Lei GS, Syu WJ, Liang PH, Chak KF, Hu WS, Hu ST (2011). "Repression of btuB gene transcription in Escherichia coli by the GadX protein." BMC Microbiol 11(1);33. PMID: 21314918

Nou00: Nou X, Kadner RJ (2000). "Adenosylcobalamin inhibits ribosome binding to btuB RNA." Proc Natl Acad Sci U S A 97(13);7190-5. PMID: 10852957


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Please cite the following article in publications resulting from the use of EcoCyc: Nucleic Acids Research 41:D605-12 2013
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