Salmonella typhimurium Enterobactin

Poliak JR, Neilands JB (1970) Enterobactin, an Iron Transport Compound from Salmonella typhimurium. Biochem Biophys Res Commun 38 989... 

Enterobactin was originally isolated from bacterial cultures of Salmonella typhimurium or Escherichia coll by lengthy extraction and chromatographic purification procedures giving yields in the region of 15 mg of product per litre of nutrient solution. Understandably, the exacting nature of this procedure has led to the development of a number of laboratory procedures to produce enterobactin synthetically. The most efficient of these makes use of the template effect (Section 3.9.1) involving the trimerisation of bulky triphenylmethyl substituted L-serine derivative about a tin atom (Scheme 3.28). 

Figure 4. Biosynthetic pathway from chorismate to enterobactin showing nature of the class I and class II mutations in Salmonella typhimurium LT-2...

The Catechol-Containing Siderophore—Enterobactin. The isolation and characterization of the cyclic triester 2,3-dihydroxy-N-benzoyl-Z-serine, a tricatechol siderophore (Figure 4), were independently reported by both Pollack and Neilands (18) and O Brien and Gibson (19). The ligand was isolated from cultures of Salmonella typhimurium and Escherichia coli and given the names enterobactin and enterochelin, respectively. Enterobactin is an efficient cellular transport agent but, unlike ferrichrome, intracellular release of the iron involves enzymatic hydrolysis of the enterobactin to the monomer, 2,3-dihydroxy-N-benzoyl-Z-ser-ine (1). 

The purpose of this chapter is to describe the competition for iron between iron-binding proteins of the animal and the siderophores of bacterial parasites. This discussion will be limited to two bacterial species—a slow-growing organism Mycobacterium tuberculosis and a fast-growing organism Escherichia coli. Both organisms produce specific siderophores which have been defined chemically and physically. Myco-bactin, the siderophore of M. tuberculosis, because of its hydrophobic nature, is associated mostly with the lipoidal cell wall of the tubercle bacillus (11) whereas enterochelin (enterobactin), the siderophore of E. coli and Salmonella typhimurium, is soluble in water and is rapidly lost by the bacterial cell into the surrounding medium (12, 13). 

Enterobactin (87) is a 12-membered ring macrotriolide initially isolated from Salmonella typhimurium [110]. It is involved in microbial transport and metabolism of iron. It is an iron-sequestering agent of the phenolate group and is overproduced by Escherichia coli and related enteric bacteria under low-iron stress. 

Pollack, J. R., and Neilands, J. B. (1970). Enterobactin, an iron transport compound from Salmonella typhimurium. Biochem. Biophys. Res. Commun. 38, 989—992. 

---