Location of Three Genes Concerned with the Conversion of 2, 3-Dihydroxybenzoate into Enterochelin in Escherichia coli K-12

Abstract

Mutants of Escherichia coli K-12 unable to synthesize the iron-sequestering compound, enterochelin, from 2,3-dihydroxybenzoate have been isolated and divided into three classes on the basis of tests for enzymatic complementation. The genes affected (designated entD, entE , and entF ) have been mapped by cotransduction and are located at about minute 14 on the E. coli genome. They were found to be closely linked to other genes ( entA, entB , and entC ) concerned with enterochelin biosynthesis and a gene ( fep ) concerned with the uptake of the iron-enterochelin complex. No detectable diffusible intermediate in the formation of enterochelin from 2,3-dihydroxybenzoate was formed by cell extracts of mutants carrying mutations in the entD, entE , or entF genes.

The Escherichia coli enterobactin biosynthesis gene, entD: nucleotide sequence and membrane localization of its protein product

“…During column chromatography, the EntD component co-e!uted with the EntF and EntG activities. This observation, along with the discovery of enzyme-bound enterobactin intermediates (Bryce and Brot, 1972;Luke and Gibson, 1971), gave rise to the speculation that EntD, EntF, EntG, and EntE functioned as a multi-enzyme complex in vivo (Greenwood and Luke, 1976). Although there was no direct demonstration of physical association of these components, it was proposed that the synthetase complex might interact with the cytoplasmic membrane via EntD (Greenwood and Luke, 1976).…”

Mu-induced polarity in the Escherichia coli K-12 ent gene cluster: evidence for a gene (entG) involved in the biosynthesis of enterochelin

“…Enzymic complementation with entD-, entE-, and entFmutants. In the conversion of 2,3-dihydroxybenzoate into enterochelin, three separate classes of mutations have been identified and named entD-, entE-, and entF- (11). To determine which gene(s) was affected by the Mu-induced mutation, cell extracts of each of the mutant strains were mixed in turn with a cell extract from strain AN462, and the overall reaction from 2,3-dihydroxybenzoate into enterochelin was measured.…”

“…Ferric-enterochelin is then hydrolyzed by ferricenterochelin esterase, making available the iron for cell metabolism. Six genes concerned with the biosynthesis of enterochelin have been identified (entA to F) (11,23), together with a gene concerned with ferric-enterochelin uptake (fep) (3) and a gene concerned with hydrolysis of the complex (fesB) (8). All eight genes are clustered within approximately 0.5 min of chromosome between the purE and lip genes at min 13 (11,20,23).…”

“…Six genes concerned with the biosynthesis of enterochelin have been identified (entA to F) (11,23), together with a gene concerned with ferric-enterochelin uptake (fep) (3) and a gene concerned with hydrolysis of the complex (fesB) (8). All eight genes are clustered within approximately 0.5 min of chromosome between the purE and lip genes at min 13 (11,20,23). The expression of the fes and ent genes has been shown to be regulated by the intracellular levels of iron (13,16,21).…”

Regulation of enterobactin iron transport in Escherichia coli: characterization of ent::Mu d(Apr lac) operon fusions

“…From a common intermediate of aromatic amino acid synthesis, the enterobactin biosynthesis genes entC, entB, and entA convert chorismate to 2,3-hihydroxybenzoic acid (32). 2,3-Dihydroxybenzoic acid and Lserine are substrates for the production of enterobactin by enterobactin synthetase, which is composed of four enzymes, the products of entD, entE, entF, and entG (20,29). Release of the siderophore into the medium occurs by an uncharacterized mechanism.…”