Recognition and transport of ferric enterobactin in Escherichia coli
The specificity of the outer membrane protein receptor for ferric enterobactin transport in Escherichia coli and the mechanism of enterobactin-mediated transport of ferric ions across the outer membrane have been studied. Transport kinetic and inhibition studies with ferric enterobactin and synthetic structural analogs have mapped the parts of the molecule important for receptor binding. The ferric complex of the synthetic structural analog of enterobactin, 1,3,5-N,N',N''-tris'(2,3-dihydroxybenzoyl)triaminomethylbenzene (MECAM), was transported with the same maximum velocity as was ferric enterobactin. A double-label transport assay with (/sup 59/Fe, /sup 3/H)MECAM showed that the ligand and the metal are transported across the outer membrane at an identical rate. Under the growth conditions used, large fractions of the transported complexes were available for exchange across the outer membrane when a large excess of extracellular complex was added to the cell suspension; at least 60% of the internalized (/sup 59/Fe)enterobactin exchanged with extracellular (/sup 55/Fe)enterobactin. Internalized (/sup 59/Fe, /sup 3/H)MECAM was released from the cell as the intact complex when either unlabeled Fe-MECAM or Fe-enterobactin was added extracellularly. The results suggest a mechanism of active transport of unmodified coordination complex across the outer membrane with possible accumulation in the periplasm.
- Research Organization:
- Univ. of California, Berkeley
- OSTI ID:
- 6937266
- Journal Information:
- J. Bacteriol.; (United States), Journal Name: J. Bacteriol.; (United States) Vol. 167:2; ISSN JOBAA
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
59 BASIC BIOLOGICAL SCIENCES
BACTERIA
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
BIOCHEMICAL REACTION KINETICS
COMPLEXES
DAYS LIVING RADIOISOTOPES
DOUBLE LABELLING
ESCHERICHIA COLI
EVEN-ODD NUCLEI
INHIBITION
INTERMEDIATE MASS NUCLEI
IRON 59
IRON COMPLEXES
IRON ISOTOPES
ISOTOPES
KINETICS
LABELLED COMPOUNDS
LABELLING
MEMBRANE TRANSPORT
MICROORGANISMS
NUCLEI
RADIOISOTOPES
REACTION KINETICS
TRANSITION ELEMENT COMPLEXES
TRITIUM COMPOUNDS
UPTAKE