Biomaterial Database

Nucleotide sequence of the btuCED genes involved in vitamin B12 transport in Escherichia coli and homology with components of periplasmic-binding-protein-dependent transport systems. 1986

M J Friedrich, and L C de Veaux, and R J Kadner

The products of the btuCED region of the Escherichia coli chromosome participate in the transport of vitamin B12 across the cytoplasmic membrane. The nucleotide sequence of the 3,410-base-pair HindIII-HincII DNA fragment carrying a portion of the himA gene and the entire btuCED region was determined. Comparison of the location of the open reading frames with the gene boundaries defined by transposon insertions allowed the assignment of polypeptide products to gene sequences. The btuC product is a highly nonpolar integral membrane protein of molecular weight 31,683. The distribution of hydrophobic regions suggests the presence of numerous membrane-spanning domains. The btuD product is a relatively polar but membrane-associated polypeptide of Mr 27,088 and contains segments bearing extensive homology to the ATP-binding peripheral membrane constituents of periplasmic binding protein-dependent transport systems. Other regions of this protein are similar to portions of the outer membrane vitamin B12 receptor. The btuE product (Mr 20,474) appears to have a periplasmic location. It has the mean hydropathy of a soluble protein but lacks an obvious signal sequence. The cellular locations and structural and sequence homologies of the Btu polypeptides point to the similarity of these three proteins to components of binding protein-dependent transport systems. However, the dependence on a periplasmic vitamin B12-binding protein has not yet been demonstrated.

UI	MeSH Term	Description	Entries
D008565	Membrane Proteins	Proteins which are found in membranes including cellular and intracellular membranes. They consist of two types, peripheral and integral proteins. They include most membrane-associated enzymes, antigenic proteins, transport proteins, and drug, hormone, and lectin receptors.	Cell Membrane Protein,Cell Membrane Proteins,Cell Surface Protein,Cell Surface Proteins,Integral Membrane Proteins,Membrane-Associated Protein,Surface Protein,Surface Proteins,Integral Membrane Protein,Membrane Protein,Membrane-Associated Proteins,Membrane Associated Protein,Membrane Associated Proteins,Membrane Protein, Cell,Membrane Protein, Integral,Membrane Proteins, Integral,Protein, Cell Membrane,Protein, Cell Surface,Protein, Integral Membrane,Protein, Membrane,Protein, Membrane-Associated,Protein, Surface,Proteins, Cell Membrane,Proteins, Cell Surface,Proteins, Integral Membrane,Proteins, Membrane,Proteins, Membrane-Associated,Proteins, Surface,Surface Protein, Cell
D002352	Carrier Proteins	Proteins that bind or transport specific substances in the blood, within the cell, or across cell membranes.	Binding Proteins,Carrier Protein,Transport Protein,Transport Proteins,Binding Protein,Protein, Carrier,Proteins, Carrier
D004926	Escherichia coli	A species of gram-negative, facultatively anaerobic, rod-shaped bacteria (GRAM-NEGATIVE FACULTATIVELY ANAEROBIC RODS) commonly found in the lower part of the intestine of warm-blooded animals. It is usually nonpathogenic, but some strains are known to produce DIARRHEA and pyogenic infections. Pathogenic strains (virotypes) are classified by their specific pathogenic mechanisms such as toxins (ENTEROTOXIGENIC ESCHERICHIA COLI), etc.	Alkalescens-Dispar Group,Bacillus coli,Bacterium coli,Bacterium coli commune,Diffusely Adherent Escherichia coli,E coli,EAggEC,Enteroaggregative Escherichia coli,Enterococcus coli,Diffusely Adherent E. coli,Enteroaggregative E. coli,Enteroinvasive E. coli,Enteroinvasive Escherichia coli
D005798	Genes, Bacterial	The functional hereditary units of BACTERIA.	Bacterial Gene,Bacterial Genes,Gene, Bacterial
D000595	Amino Acid Sequence	The order of amino acids as they occur in a polypeptide chain. This is referred to as the primary structure of proteins. It is of fundamental importance in determining PROTEIN CONFORMATION.	Protein Structure, Primary,Amino Acid Sequences,Sequence, Amino Acid,Sequences, Amino Acid,Primary Protein Structure,Primary Protein Structures,Protein Structures, Primary,Structure, Primary Protein,Structures, Primary Protein
D001426	Bacterial Proteins	Proteins found in any species of bacterium.	Bacterial Gene Products,Bacterial Gene Proteins,Gene Products, Bacterial,Bacterial Gene Product,Bacterial Gene Protein,Bacterial Protein,Gene Product, Bacterial,Gene Protein, Bacterial,Gene Proteins, Bacterial,Protein, Bacterial,Proteins, Bacterial
D001483	Base Sequence	The sequence of PURINES and PYRIMIDINES in nucleic acids and polynucleotides. It is also called nucleotide sequence.	DNA Sequence,Nucleotide Sequence,RNA Sequence,DNA Sequences,Base Sequences,Nucleotide Sequences,RNA Sequences,Sequence, Base,Sequence, DNA,Sequence, Nucleotide,Sequence, RNA,Sequences, Base,Sequences, DNA,Sequences, Nucleotide,Sequences, RNA
D001692	Biological Transport	The movement of materials (including biochemical substances and drugs) through a biological system at the cellular level. The transport can be across cell membranes and epithelial layers. It also can occur within intracellular compartments and extracellular compartments.	Transport, Biological,Biologic Transport,Transport, Biologic
D012689	Sequence Homology, Nucleic Acid	The sequential correspondence of nucleotides in one nucleic acid molecule with those of another nucleic acid molecule. Sequence homology is an indication of the genetic relatedness of different organisms and gene function.	Base Sequence Homology,Homologous Sequences, Nucleic Acid,Homologs, Nucleic Acid Sequence,Homology, Base Sequence,Homology, Nucleic Acid Sequence,Nucleic Acid Sequence Homologs,Nucleic Acid Sequence Homology,Sequence Homology, Base,Base Sequence Homologies,Homologies, Base Sequence,Sequence Homologies, Base
D014805	Vitamin B 12	A cobalt-containing coordination compound produced by intestinal micro-organisms and found also in soil and water. Higher plants do not concentrate vitamin B 12 from the soil and so are a poor source of the substance as compared with animal tissues. INTRINSIC FACTOR is important for the assimilation of vitamin B 12.	Cobalamin,Cyanocobalamin,Cobalamins,Eritron,Vitamin B12,B 12, Vitamin,B12, Vitamin