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(Redirected from Siderophores)
A 'Siderophore' (Greek for iron carrier) is an iron chelating compound secreted by microorganisms. Iron Fe3+ ions have a very low solubility at neutral pH and therefore cannot be utilized by organisms. Siderophores dissolve these ions by chelation as soluble Fe3+ complexes that can be taken up by active transport mechanisms. Many siderophores are nonribosomal peptides.
To put it another way: Under anoxic conditions, iron is generally in the +2 oxidation state (ferrous) and soluble. However, under oxic conditions, iron is generally in the +3 oxidation state (ferric) and forms various insoluble minerals. To obtain iron from such minerals, cells produce iron-binding siderophores that bind iron and transport it into the cell. One major group of siderophores consists of derivatives of hydroxamic acid, which chelate ferric iron very strongly.[1]
Other strategies to enhance iron solubility and uptake are the acidification of the surrounding (e.g. used by plant roots) or the extracellular reduction of Fe3+ into the more soluble Fe2+ ions.
Examples of siderophores produced by various bacteria and fungi are ferrichrome (''Ustilago sphaerogena''), enterobactin (''Escherichia coli''), mycobactin (''Mycobacterium''), enterobactin and bacillibactin (''Bacillus subtilis''), ferrioxamine B (''Streptomyces pilosus''), fusarinine C (''Fusarium roseum''), yersiniabactin (''Yersinia pestis''), vibriobactin (''Vibrio cholerae''), azotobactin (''Azotobacter vinelandii''), pseudobactin (''Pseudomonas B 10''), erythrobactin (''Saccharopolyspora erythraea'') or ornibactin (''Burkholderia cepacia'').
1. Biology of Microorganisms, Eleventh Edition, Pearson Education
A 'Siderophore' (Greek for iron carrier) is an iron chelating compound secreted by microorganisms. Iron Fe3+ ions have a very low solubility at neutral pH and therefore cannot be utilized by organisms. Siderophores dissolve these ions by chelation as soluble Fe3+ complexes that can be taken up by active transport mechanisms. Many siderophores are nonribosomal peptides.
To put it another way: Under anoxic conditions, iron is generally in the +2 oxidation state (ferrous) and soluble. However, under oxic conditions, iron is generally in the +3 oxidation state (ferric) and forms various insoluble minerals. To obtain iron from such minerals, cells produce iron-binding siderophores that bind iron and transport it into the cell. One major group of siderophores consists of derivatives of hydroxamic acid, which chelate ferric iron very strongly.[1]
Other strategies to enhance iron solubility and uptake are the acidification of the surrounding (e.g. used by plant roots) or the extracellular reduction of Fe3+ into the more soluble Fe2+ ions.
Examples of siderophores produced by various bacteria and fungi are ferrichrome (''Ustilago sphaerogena''), enterobactin (''Escherichia coli''), mycobactin (''Mycobacterium''), enterobactin and bacillibactin (''Bacillus subtilis''), ferrioxamine B (''Streptomyces pilosus''), fusarinine C (''Fusarium roseum''), yersiniabactin (''Yersinia pestis''), vibriobactin (''Vibrio cholerae''), azotobactin (''Azotobacter vinelandii''), pseudobactin (''Pseudomonas B 10''), erythrobactin (''Saccharopolyspora erythraea'') or ornibactin (''Burkholderia cepacia'').
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| References |
References
1. Biology of Microorganisms, Eleventh Edition, Pearson Education
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