TCDB is operated by the Saier Lab Bioinformatics Group
« See all members of the family


1.B.14.3.1
BtuB cobalamin receptor (also transports phage C1 DNA across the outer membrane). Two Ca2+ binding sites in BtuB mediate cobalamine binding (Cadieux et al., 2007). Cobalamine uptake into the periplasm is reversible, but efflux is pmf-independent (Cadieux et al., 2007). The 3-d structure is available (PDB#1NQE).  The Ton box and the extracellular substrate binding site are allosterically coupled (bidirectional), and TonB binding may initiate a partial round of transport (Sikora et al. 2016).  Substrate binding to the extracellular surface of the protein triggers the unfolding of an energy coupling motif at the periplasmic surface.  Thus, substrate binding reduces the interaction free energy between certain residues, thereby triggering the unfolding of the energy coupling motif (Lukasik et al. 2007).

Accession Number:P06129
Protein Name:BtuB aka BFE aka CER aka DCRC aka B3966
Length:614
Molecular Weight:68407.00
Species:Escherichia coli [83333]
Location1 / Topology2 / Orientation3: Cell outer membrane1 / Multi-pass membrane protein2
Substrate Vitamin B12

Cross database links:

Genevestigator: P06129
EchoBASE: EB0124
EcoGene: EG10126
eggNOG: COG4206
HEGENOM: HBG644936
DIP: DIP-9232N
RefSeq: AP_003844.1    NP_418401.1   
Entrez Gene ID: 948468   
Pfam: PF07715    PF00593   
Drugbank: Drugbank Link   
BioCyc: EcoCyc:EG10126-MONOMER    ECOL168927:B3966-MONOMER   
KEGG: ecj:JW3938    eco:b3966   

Gene Ontology

GO:0009279 C:cell outer membrane
GO:0005886 C:plasma membrane
GO:0046930 C:pore complex
GO:0015235 F:cobalamin transporter activity
GO:0046872 F:metal ion binding
GO:0005515 F:protein binding
GO:0004872 F:receptor activity
GO:0015889 P:cobalamin transport
GO:0009597 P:detection of virus
GO:0046718 P:entry of virus into host cell
GO:0006811 P:ion transport

References (15)

[1] “Nucleotide sequence of the gene for the vitamin B12 receptor protein in the outer membrane of Escherichia coli.”  Heller K.et.al.   3882670
[2] “Analysis of the Escherichia coli genome. IV. DNA sequence of the region from 89.2 to 92.8 minutes.”  Blattner F.R.et.al.   8265357
[3] “The complete genome sequence of Escherichia coli K-12.”  Blattner F.R.et.al.   9278503
[4] “Highly accurate genome sequences of Escherichia coli K-12 strains MG1655 and W3110.”  Hayashi K.et.al.   16738553
[5] “The trmA promoter has regulatory features and sequence elements in common with the rRNA P1 promoter family of Escherichia coli.”  Gustafsson C.et.al.   1999392
[6] “Comparing the predicted and observed properties of proteins encoded in the genome of Escherichia coli K-12.”  Link A.J.et.al.   9298646
[7] “The Escherichia coli mutant requiring D-glutamic acid is the result of mutations in two distinct genetic loci.”  Dougherty T.J.et.al.   8093236
[8] “Point mutations in a conserved region (TonB box) of Escherichia coli outer membrane protein BtuB affect vitamin B12 transport.”  Gudmundsdottir A.et.al.   2687240
[9] “Coupled changes in translation and transcription during cobalamin-dependent regulation of btuB expression in Escherichia coli.”  Nou X.et.al.   9852020
[10] “Site-directed disulfide bonding reveals an interaction site between energy-coupling protein TonB and BtuB, the outer membrane cobalamin transporter.”  Cadieux N.et.al.   10485884
[11] “Transport-defective mutations alter the conformation of the energy-coupling motif of an outer membrane transporter.”  Coggshall K.A.et.al.   11705387
[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.et.al.   14499604
[13] “Crystallization and initial X-ray diffraction of BtuB, the integral membrane cobalamin transporter of Escherichia coli.”  Chimento D.P.et.al.   12595710
[14] “Substrate-induced transmembrane signaling in the cobalamin transporter BtuB.”  Chimento D.P.et.al.   12652322
[15] “The structure of BtuB with bound colicin E3 R-domain implies a translocon.”  Kurisu G.et.al.   14528295
Structure:
1NQE   1NQF   1NQG   1NQH   1UJW   2GSK   2GUF   2YSU   3M8B   3M8D   [...more]

External Searches:

  • Search: DB with
  • BLAST ExPASy (Swiss Institute of Bioinformatics (SIB) BLAST)
  • CDD Search (Conserved Domain Database)
  • Search COGs (Clusters of Orthologous Groups of proteins)
  • 2° Structure (Network Protein Sequence Analysis)

Analyze:

Predict TMSs (Predict number of transmembrane segments)
Window Size: Angle:  
Window Size: Angle:  
FASTA formatted sequence
1:	MIKKASLLTA CSVTAFSAWA QDTSPDTLVV TANRFEQPRS TVLAPTTVVT RQDIDRWQST 
61:	SVNDVLRRLP GVDITQNGGS GQLSSIFIRG TNASHVLVLI DGVRLNLAGV SGSADLSQFP 
121:	IALVQRVEYI RGPRSAVYGS DAIGGVVNII TTRDEPGTEI SAGWGSNSYQ NYDVSTQQQL 
181:	GDKTRVTLLG DYAHTHGYDV VAYGNTGTQA QTDNDGFLSK TLYGALEHNF TDAWSGFVRG 
241:	YGYDNRTNYD AYYSPGSPLL DTRKLYSQSW DAGLRYNGEL IKSQLITSYS HSKDYNYDPH 
301:	YGRYDSSATL DEMKQYTVQW ANNVIVGHGS IGAGVDWQKQ TTTPGTGYVE DGYDQRNTGI 
361:	YLTGLQQVGD FTFEGAARSD DNSQFGRHGT WQTSAGWEFI EGYRFIASYG TSYKAPNLGQ 
421:	LYGFYGNPNL DPEKSKQWEG AFEGLTAGVN WRISGYRNDV SDLIDYDDHT LKYYNEGKAR 
481:	IKGVEATANF DTGPLTHTVS YDYVDARNAI TDTPLLRRAK QQVKYQLDWQ LYDFDWGITY 
541:	QYLGTRYDKD YSSYPYQTVK MGGVSLWDLA VAYPVTSHLT VRGKIANLFD KDYETVYGYQ 
601:	TAGREYTLSG SYTF