Description

Siderophores are small, high-affinity iron chelating agent, and many microorganisms have the ability to secrete for the acquisition of iron under iron deficiency conditions (because the iron is solid in the general natural environment with very low concentration of iron ions) and transport through membrane transporter. Siderophore are one of the strongest soluble ferric chelators known in the world. The structure and properties of siderophore produced by different organisms vary widely. The types include: catechins, hydroxamates and carboxylates. enterobactin is the strongest siderophore known, binding to the Fe3+ with the affinity (K = 1052 M−1).So we will engineer the siderophore system of E. coli.

Design

The natural siderophore producing is affected by the concentration of iron ions. Through the regulation mechanism of Fur, when the iron ion concentration is high, the siderophore gene is inhibited, and thus the siderophore is no longer produced. Therefore, we need to modify the natural siderophore system to initiate the expression of the siderophore gene when the quorum sensing signal molecule HSL is present.

Chorismic acid, an aromatic amino acid precursor, is converted to 2,3-dihydroxybenzoic acid (DHB) by a series of enzymes, EntA, EntB and EntC. An amide linkage of DHB to L-serine is then catalyzed by EntD, EntE, EntF and EntB. Three molecules of the DHB-Ser formed undergo intermolecular cyclization, yielding enterobactin.