PMID:3309133

Citation	Pugsley, AP, Moreno, F and de Lorenzo, V (1986) Microcin-E492-insensitive mutants of Escherichia coli K12.J. Gen. Microbiol. 132:3253-9
Abstract	Mutations in three Escherichia coli K12 genes, tonB, exbB and the newly discovered semA, reduce sensitivity to the low Mr polypeptide antibiotic microcin E492. The products of the tonB and exbB genes were previously shown to be involved in the uptake of siderophore-complexed iron and in the action of a number of colicins. Strains mutated at or close to semA (collectively referred to as sem mutations) remained fully sensitive to these colicins, and grew as well as wild-type strains under conditions of iron starvation. Expression of a number of sem-lacZ operon fusions was not affected by iron limitation, and sem mutations did not affect the production of iron-regulated outer membrane proteins which are known or thought to be involved in iron uptake. Hfr conjugation and P1 phage transduction experiments indicated that semA is located close to pabB at 40 min on the E. coli K12 chromosome. This places semA close to the mng locus, wherein mutations result in decreased manganese sensitivity. However, strains carrying the semA mutation exhibited increased manganese sensitivity.
Links	PubMed
Keywords	Anti-Bacterial Agents; Bacteriocins; Chromosome Mapping; Cloning, Molecular; Drug Resistance, Microbial; Escherichia coli; Genes, Bacterial; Manganese; Mutation; Transduction, Genetic
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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
a mutation or genetic difference within a strain	Taxon: Escherichia coli Strain: K-12 Substrain: PAP710 NCBI Taxon ID: 83333	Genotype of Reference Strain: PAP710 semA⁺ Genotype of Experimental Strain : PAP710 Sem^-	Reference Condition:	0000276	increased resistance to antibiotics	0000033	traceable author statement	Reduced sensitivity to microcin E492, sensitive to 100 to 250 antibiotic units compared to 1 antibiotic unit for the wildtype. See page 3255 of the paper.
a mutation or genetic difference within a strain	Taxon: Escherichia coli Strain: K-12 Substrain: PAP710 NCBI Taxon ID: 83333	Genotype of Reference Strain: exbB⁺ Genotype of Experimental Strain : ExbB^- in PAP710	Reference Condition:	0000276	increased resistance to antibiotics	0000181	in vitro assay data	Mutation causes extensive resistance to various colicins including Microcin E492
a mutation or genetic difference within a strain	Taxon: Escherichia coli Strain: K-12 Substrain: PAP710 NCBI Taxon ID: 83333	Genotype of Reference Strain: tonB⁺ Genotype of Experimental Strain : TonB^- in PAP710	Reference Condition:	0000276	increased resistance to antibiotics	0000181	in vitro assay data	Mutation causes extensive resistance to various colicins including Microcin E492 which it was completely resistant too.
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