Citrate siderophores

Cyanobacteria were probably the first organisms to perform oxygenic photosynthesis resulting eventually in the oxidation of environmental Fe " to Fe " with all its consequences. To cope with this problem the production of siderophores was initiated. Not much is known about the siderophores of cyanobacteria. Schizokinen (see below under citrate siderophores, Sect. 4.1) (326) found to be produced by several bacterial species may have been acquired by gene transfer see however also the citrate siderophores synechobactins. 

For other fungal siderophores see neurosporin above, pistilarin (a spermidine derivative, Sect. 3.2) and rhizoferrin (a citrate siderophore, Sect. 4.4) siderophores... 

Alcaligin E from Alcaligenes eutrophus is described from color tests as a phenolic siderophore (126a). According to a recent publication (90a) it is identical with staphyloferrin B, a citrate siderophore (Sect. 4.2). No further information is given to resolve these discrepancies. 

Chart 3. Cyclization of citrate siderophores to amidic structures... 

Fig. 15. Citrate siderophores with two hydroxamic acid units...

Budzikiewicz H (2004) Siderophores of the Pseudomonadaceae sensu stricto (Fluorescent and Non-fluorescent Pseudomonas spp.). Progr Chem Org Nat Prod 87 81 Budzikiewicz H (2004) Bacterial Catecholate Siderophores. Mini-Rev Org Chem 1 163 Budzikiewicz H (2005) Bacterial Citrate Siderophores. Mini-Rev Org Chem 3 119 Budzikiewicz H (2006) Bacterial Aromatic Sulfonates - a Bucherer Reaction in Nature Mini-Rev Org Chem 3 93... 

Mtinzinger M, Budzikiewicz H, Expert D, Enard C, Meyer JM (2000) Achromobactin, a New Citrate Siderophore of Erwinia chrysanthemi. Z Naturforsch 55c 328... 

Mtinzinger M, Taraz K, Budzikiewicz H (1999) Staphyloferrin B, a Citrate Siderophore from Ralstonia eutropha. Z Naturforsch 54c 867... 

Legionella pneumophila produces a siderophore named legiobactin, which shows no catecholate or hydroxamate reactions (206). Enzymatic studies suggest a citrate structure in agreement with the data obtained by mass spectrometry (molecular mass ca. 350 Da) and NMR (three carbonyl and ten aliphatic C atoms). It is not clear yet as to whether legiobactin is essential for the iron acquisition in the aqueous habitat of the bacterium or during lung infection (2, 65). 

Okujo N, Sakakibara Y, Yoshida T, Yamamoto S. (1994) Structure of Acinetoferrin, a New Citrate-based Dihydroxamate Siderophore from Acinetobacter haemolyticus. BioMetals 7 170... 

Ghosh A, Miller MJ (1993) Synthesis of Novel Citrate-Based Siderophores and Side-rophore-p iactam Conjugates. Iron Transport-mediated Dmg Delivery Systems. J Org Chem 58 7652... 

Escherichia coli has at least five independent transport systems, one of which is the low affinity pathway described above. In addition, it synthesizes enterobactin as a siderophore it can take up the iron(III) complex of ferrichrome, a siderophore synthesized by certain fungi there is a citrate-induced system, and a less common process involving aerobactin. 

Siderophores with citrate-hydroxamate structures (schizokinen, arthrobactin and aerobactin) are synthesized by enteric bacilli and Arthrobacter spp. Their structures are shown in Figure 48. 

Figure 12. Uptake of the radioactive label of 55Fe-ferrichrome (O), A-cis-chromic-3H-deferrifer-richrome ( ), 3H-ferrichrome (A), and 3H-ferri-chrome with excess ferric citrate (A) in Salmonella typhimurium LT-2. Cell optical density at 650 nm was 1.2, and siderophore concentration was 0.5 /xM (62).

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