PMID:2670903

Citation	Eick-Helmerich, K and Braun, V (1989) Import of biopolymers into Escherichia coli: nucleotide sequences of the exbB and exbD genes are homologous to those of the tolQ and tolR genes, respectively.J. Bacteriol. 171:5117-26
Abstract	Escherichia coli with mutations in the exb region are impaired in outer membrane receptor-dependent uptake processes. They are resistant to the antibiotic albomycin and exhibit reduced sensitivity to group B colicins. A 2.2-kilobase-pair DNA fragment of the exb locus was sequenced. It contained two open reading frames, designated exbB and exbD, which encoded polypeptides of 244 and 141 amino acids, respectively. Both proteins were found in the cytoplasmic membrane. They showed strong homologies to the TolQ and TolR proteins, respectively, which are involved in uptake of group A colicins and infection by filamentous bacteriophages. exbB and exbD were required to complement exb mutations. Osmotic shock treatment rendered exb mutants sensitive to colicin M, which was taken as evidence that the ExbB and ExbD proteins are involved in transport processes across the outer membrane. It is concluded that the exb- and tol-dependent systems originate from a common uptake system for biopolymers.
Links	PubMed
Keywords	Amino Acid Sequence; Bacterial Proteins; Base Sequence; Biopolymers; DNA, Recombinant; Escherichia coli; Escherichia coli Proteins; Genes; Genes, Bacterial; Genotype; Membrane Proteins; Molecular Sequence Data; Plasmids; Sequence Homology, Nucleic Acid
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Phenotype of	Taxon Information	Genotype Information (if known)	Condition Information	OMP ID	OMP Term Name	ECO ID	ECO Term Name	Notes	Status
a mutation or genetic difference within a strain	Taxon: Escherichia coli Strain: K-12 Substrain: AB2847 NCBI Taxon ID: 83333	Genotype of Reference Strain: exbB Genotype of Experimental Strain : exbB (pKE67	Reference Condition:	0000276	increased resistance to antimicrobial compound			Resistance to Albomycin
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