The world's first wiki where authorship really matters (Nature Genetics, 2008). Due credit and reputation for authors. Imagine a global collaborative knowledge base for original thoughts. Search thousands of articles and collaborate with scientists around the globe.

wikigene or wiki gene protein drug chemical gene disease author authorship tracking collaborative publishing evolutionary knowledge reputation system wiki2.0 global collaboration genes proteins drugs chemicals diseases compound
Hoffmann, R. A wiki for the life sciences where authorship matters. Nature Genetics (2008)
Gene Review

btuB  -  vitamin B12/cobalamin outer membrane...

Escherichia coli O157:H7 str. Sakai

Welcome! If you are familiar with the subject of this article, you can contribute to this open access knowledge base by deleting incorrect information, restructuring or completely rewriting any text. Read more.

Disease relevance of ECs4897

  • Cellular import of colicin E3 is initiated by the Escherichia coli outer membrane cobalamin transporter, BtuB [1].
  • The BtuB protein of Escherichia coli is a multifunctional outer membrane receptor required for the binding and uptake of vitamin B12, bacteriophage BF23, and the E colicins [2].
  • BtuB is a TonB-dependent transport protein that binds and carries vitamin B(12) across the outer membrane of Gram negative bacteria such as Escherichia coli [3].
  • Analyses of the primary sequence of hemoglobin-binding protein HgbA from Actinobacillus pleuropneumoniae by comparative modelling and by a Hidden Markov Model identified its topological similarities to bacterial outer membrane receptors BtuB, FepA, FhuA, and FecA of Escherichia coli [4].

High impact information on ECs4897

  • We go on to delineate key features of the "colicin translocon" that assembles at the cell surface after BtuB binding by using a complex of histidine-tagged Im9 bound to ColE9S-S [5].
  • The BtuB transporter mediates high-affinity binding and TonB-dependent active transport of vitamin B12 [cyanocobalamin (CNCbl)] across the outer membrane of Escherichia coli [6].
  • An in vivo method of detecting substrate-induced changes in the Ton box environment measured reaction of a biotin maleimide derivative with cysteine substitutions through the N-terminal region of BtuB between positions 1 and 31 [6].
  • Crosslinking at several positions was increased when BtuB was loaded with substrate, and the crosslinking pattern was altered by the presence of substitutions in BtuB that cause a TonB-uncoupled phenotype [7].
  • Fluorescein-labeled E-peptide-1 binds to purified BtuB in a calcium-dependent manner with a Kd of 43.6 +/- 4.9 nm or 2370 +/- 670 nm in the presence or absence of calcium, respectively [8].

Chemical compound and disease context of ECs4897

  • We had previously shown that the Escherichia coli proteins DcrA (SdaC) and DcrB, located, respectively, in the inner membrane and periplasm, are involved in the early development of virulent bacteriophage C1, which recognises BtuB as an outer membrane receptor [9].

Biological context of ECs4897

  • An amino acid substitution within the conserved amino-terminal region of BtuB resulted in production of a receptor that had normal binding functions but was incapable of energy-dependent transport of vitamin B12 [10].
  • We conclude that the BtuB binding sites for cobalamins and enzymatic E-colicins are overlapping but inequivalent and that the distal loop and (possibly) the short alpha-helical flanking regions are sufficient for high affinity binding [8].
  • Mutations located in the minimum R domain that abolished or reduced the biological activity of colicin E9 similarly affected the competitive binding of the mutant colicin protein to BtuB [11].
  • Homology searches of bacterial genomes, structural annotation based on the presence of conserved Cbl-binding residues identified by analysis of our BtuB structure, and detection of homologs of the periplasmic Cbl-binding binding protein BtuF enable identification of putative BtuB orthologs in enteric and non-enteric bacterial species [12].
  • This suppression activity was associated with the plasmid, suggesting that a mutation within the tonB gene on the plasmid allowed the mutant BtuB receptor to function in the transport of the vitamin [13].

Anatomical context of ECs4897

  • This binding event establishes a distinct RNA structure that is likely to be responsible for inhibition of ribosome binding and consequent reduction in synthesis of the cobalamin transport protein BtuB [14].
  • This conformational change and the similarity in the EPR spectra between reconstituted and native membranes indicate that BtuB is correctly folded and functional in the reconstituted system [15].
  • Transport of CN-Cbl across the outer membrane and its accumulation in the periplasm is mediated by the TonB-dependent transporter BtuB [16].
  • Hybrid proteins in which various lengths from the amino terminus of BtuB were linked to alkaline phosphatase (btuB::phoA genes) were all secreted across the cytoplasmic membrane [17].

Associations of ECs4897 with chemical compounds

  • Efficient purification of overexpressed BtuB containing stoichiometric levels of bound lipopolysaccharide has been achieved through the extraction of the outer membrane with nonionic detergent followed by ion-exchange chromatography [18].
  • BtuB mutants were expressed, spin labeled, purified, and reconstituted into phosphatidylcholine [15].
  • Here, we incorporate pairs of nitroxide spin labels into membrane reconstituted BtuB and utilize a four-pulse double electron-electron resonance (DEER) experiment to measure distances between the Ton box and the periplasmic surface of the transporter with and without substrate [3].
  • Although CN-Cbl uptake does not inhibit ferrichrome uptake in wild-type cells, in which the amount of the outer membrane ferrichrome transporter FhuA far exceeds that of the cobalamin transporter BtuB, CN-Cbl does inhibit ferrichrome uptake when BtuB is overexpressed from a multicopy plasmid [19].
  • BtuB was purified in the detergent LDAO (n-dodecyl-N,N-dimethylamine-N-oxide) and the complex was formed in a detergent mixture of LDAO and C8E4 (tetraethylene glycol monooctylether) [20].

Analytical, diagnostic and therapeutic context of ECs4897

  • We report isothermal titration calorimetry data of BtuB binding the endonuclease toxin ColE9 and a disulfide form (ColE9S-S) where unfolding of the coiled-coil is prevented and, as a consequence, the toxin is biologically inactive [5].
  • Crystallization and initial X-ray diffraction of BtuB, the integral membrane cobalamin transporter of Escherichia coli [21].
  • The results of Western blotting detected a decrease in the protein expression levels of BtuB and OmpF involved in colicin translocation in the lon mutant [22].


  1. The structure of BtuB with bound colicin E3 R-domain implies a translocon. Kurisu, G., Zakharov, S.D., Zhalnina, M.V., Bano, S., Eroukova, V.Y., Rokitskaya, T.I., Antonenko, Y.N., Wiener, M.C., Cramer, W.A. Nat. Struct. Biol. (2003) [Pubmed]
  2. Altered binding and transport of vitamin B12 resulting from insertion mutations in the Escherichia coli btuB gene. Gudmundsdottir, A., Bradbeer, C., Kadner, R.J. J. Biol. Chem. (1988) [Pubmed]
  3. Substrate-dependent unfolding of the energy coupling motif of a membrane transport protein determined by double electron-electron resonance. Xu, Q., Ellena, J.F., Kim, M., Cafiso, D.S. Biochemistry (2006) [Pubmed]
  4. Hemoglobin-binding protein HgbA in the outer membrane of Actinobacillus pleuropneumoniae: homology modelling reveals regions of potential interactions with hemoglobin and heme. Pawelek, P.D., Coulton, J.W. J. Mol. Graph. Model. (2004) [Pubmed]
  5. Cell entry mechanism of enzymatic bacterial colicins: porin recruitment and the thermodynamics of receptor binding. Housden, N.G., Loftus, S.R., Moore, G.R., James, R., Kleanthous, C. Proc. Natl. Acad. Sci. U.S.A. (2005) [Pubmed]
  6. Differential substrate-induced signaling through the TonB-dependent transporter BtuB. Cadieux, N., Phan, P.G., Cafiso, D.S., Kadner, R.J. Proc. Natl. Acad. Sci. U.S.A. (2003) [Pubmed]
  7. Site-directed disulfide bonding reveals an interaction site between energy-coupling protein TonB and BtuB, the outer membrane cobalamin transporter. Cadieux, N., Kadner, R.J. Proc. Natl. Acad. Sci. U.S.A. (1999) [Pubmed]
  8. Enzymatic E-colicins bind to their target receptor BtuB by presentation of a small binding epitope on a coiled-coil scaffold. Mohanty, A.K., Bishop, C.M., Bishop, T.C., Wimley, W.C., Wiener, M.C. J. Biol. Chem. (2003) [Pubmed]
  9. DcrA and dcrB Escherichia coli genes can control DNA injection by phages specific for BtuB and FhuA receptors. Samsonov, V.V., Samsonov, V.V., Sineoky, S.P. Res. Microbiol. (2002) [Pubmed]
  10. Nucleotide sequence of the gene for the ferrienterochelin receptor FepA in Escherichia coli. Homology among outer membrane receptors that interact with TonB. Lundrigan, M.D., Kadner, R.J. J. Biol. Chem. (1986) [Pubmed]
  11. A 76-residue polypeptide of colicin E9 confers receptor specificity and inhibits the growth of vitamin B12-dependent Escherichia coli 113/3 cells. Penfold, C.N., Garinot-Schneider, C., Hemmings, A.M., Moore, G.R., Kleanthous, C., James, R. Mol. Microbiol. (2000) [Pubmed]
  12. The Escherichia coli outer membrane cobalamin transporter BtuB: structural analysis of calcium and substrate binding, and identification of orthologous transporters by sequence/structure conservation. Chimento, D.P., Kadner, R.J., Wiener, M.C. J. Mol. Biol. (2003) [Pubmed]
  13. Suppression of the btuB451 mutation by mutations in the tonB gene suggests a direct interaction between TonB and TonB-dependent receptor proteins in the outer membrane of Escherichia coli. Heller, K.J., Kadner, R.J., Günther, K. Gene (1988) [Pubmed]
  14. Genetic control by a metabolite binding mRNA. Nahvi, A., Sudarsan, N., Ebert, M.S., Zou, X., Brown, K.L., Breaker, R.R. Chem. Biol. (2002) [Pubmed]
  15. Substrate-induced conformational changes of the periplasmic N-terminus of an outer-membrane transporter by site-directed spin labeling. Fanucci, G.E., Coggshall, K.A., Cadieux, N., Kim, M., Kadner, R.J., Cafiso, D.S. Biochemistry (2003) [Pubmed]
  16. Identification of the periplasmic cobalamin-binding protein BtuF of Escherichia coli. Cadieux, N., Bradbeer, C., Reeger-Schneider, E., Köster, W., Mohanty, A.K., Wiener, M.C., Kadner, R.J. J. Bacteriol. (2002) [Pubmed]
  17. Deletions or duplications in the BtuB protein affect its level in the outer membrane of Escherichia coli. Köster, W., Gudmundsdottir, A., Lundrigan, M.D., Seiffert, A., Kadner, R.J. J. Bacteriol. (1991) [Pubmed]
  18. Purification and characterization of monomeric Escherichia coli vitamin B12 receptor with high affinity for colicin E3. Taylor, R., Burgner, J.W., Clifton, J., Cramer, W.A. J. Biol. Chem. (1998) [Pubmed]
  19. Mutual inhibition of cobalamin and siderophore uptake systems suggests their competition for TonB function. Kadner, R.J., Heller, K.J. J. Bacteriol. (1995) [Pubmed]
  20. 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. Shultis, D.D., Purdy, M.D., Banchs, C.N., Wiener, M.C. Acta Crystallograph. Sect. F Struct. Biol. Cryst. Commun. (2006) [Pubmed]
  21. Crystallization and initial X-ray diffraction of BtuB, the integral membrane cobalamin transporter of Escherichia coli. Chimento, D.P., Mohanty, A.K., Kadner, R.J., Wiener, M.C. Acta Crystallogr. D Biol. Crystallogr. (2003) [Pubmed]
  22. An E. coli lon mutant conferring partial resistance to colicin may reveal a novel role in regulating proteins involved in the translocation of colicin. Lee, Y.Y., Hu, H.T., Liang, P.H., Chak, K.F. Biochem. Biophys. Res. Commun. (2006) [Pubmed]
WikiGenes - Universities