Bacterial catecholate siderophore-iron complex

The **bacterial catecholate siderophore-iron complex** refers to a stable coordination complex formed when a catecholate-type siderophore, such as enterobactin or bacillibactin, produced by bacteria under iron-limiting conditions, binds tightly to ferric ion (Fe^3+). Siderophores are high-affinity iron-chelating molecules that solubilize and sequester iron from the environment, which is then transported into the bacterial cell via specific outer membrane transporters and periplasmic binding proteins. Catecholate siderophores are characterized by their catechol (dihydroxybenzene) functional groups, contributing to high iron affinity and stable hexadentate (six donor atoms) complexes with Fe^3+[4][5][11]. Once the complex enters the periplasm, iron is typically released through reduction to Fe^2+ or enzymatic hydrolysis of the siderophore scaffold[11]. This process is vital for bacterial growth and virulence, as iron is an essential but often limiting nutrient, especially in host environments where iron is tightly sequestered by host proteins[3][7][8]. **Important structural and mechanistic note:** The term "bacterial catecholate siderophore-iron complex" does not itself denote a single, well-defined molecular target (such as a receptor, transporter, or enzyme) but rather a class of molecular complexes formed by the iron-binding reaction of catecholate siderophores with Fe^3+. It is not a *therapeutic target* in the conventional sense, but the associated pathways (e.g., siderophore biosynthesis, transporters such as FepA, uptake systems, or enzymes hydrolyzing the complex) are established therapeutic targets or points of intervention in antibacterial drug development[9][10][11]. Because the query specifies a *complex* and not a protein or specific molecular target, and because the complex itself is not a receptor, enzyme, or other standard drug target, the entry is marked "is_target: false" and "is_incorrect: true" for direct therapeutic target annotation. For drug discovery purposes, attention should refocus to proteins that bind, transport, or catalyze reactions involving these complexes (like siderophore receptors such as FepA or Fiu, or related ATP-binding cassette [ABC] transporters), not the iron-siderophore complex per se[1][9][10][11].

Other names

Catecholate-type siderophore-iron complexFerric-catecholate siderophore complexFe(III)-catecholate siderophore complexFerric-enterobactin complex (for specific subclasses, e.g., enterobactin)

Chelation of ferric iron (Fe^3+) by siderophores for bacterial transport and uptake Competitive inhibition of iron acquisition by structurally similar chelators or metal complexes