title: Enterochelin system of iron transport in Escherichia coli: mutations affecting ferric-enterochelin esterase.
abstract: Three mutant strains of Escherichia coli have been isolated which are lacking ferric-enterochelin esterase activity. This enzyme catalyzes the hydrolysis of the enterochelin moiety of ferric-enterochelin to yield ultimately three molecules of N-2,3-dihydroxybenzoylserine. The mutants (designated fes(-)) were shown to be unaffected in enterochelin biosynthesis, capable of enterochelin-mediated iron uptake, and able to utilize ferric-dihydroxybenzoylserine complexes normally. When grown under iron-deficient conditions, however, they showed an absolute requirement for added iron or citrate, a phenotype characteristic of mutants defective in some part of the enterochelin system of iron uptake. These results support the theory that iron, taken up by the cell as ferric-enterochelin is only available for general cell metabolism after hydrolysis of the ligand by enterochelin esterase. The three fes(-) strains were shown to be affected in the B component of enterochelin esterase. The fesB gene which is probably the structural gene coding for component B of the esterase, was shown to be located at about minute 14 on the E. coli chromosome together with seven other genes involved in the enterochelin system of iron transport.
mesh_terms: D001565:Benzoates; D001692:Biological Transport; D002384:Catalysis; D002396:Catechols; D002474:Cell-Free System; D002850:Chromatography, Gel; D002874:Chromosome Mapping; D002876:Chromosomes, Bacterial; D003470:Culture Media; D004926:Escherichia coli / Q000201:enzymology* / Q000254:growth & development / Q000378:metabolism; D004950:Esterases / Q000378:metabolism*; D005796:Genes; D005816:Genetic Complementation Test; D006868:Hydrolysis; D007501:Iron / Q000378:metabolism*; D007502:Iron Chelating Agents / Q000096:biosynthesis / Q000378:metabolism; D007503:Iron Isotopes; D009154:Mutation; D012694:Serine; D014161:Transduction, Genetic
chemical_list: D001565:Benzoates; D002396:Catechols; D003470:Culture Media; D007502:Iron Chelating Agents; D007503:Iron Isotopes; D012694:Serine; D007501:Iron; D004950:Esterases