Fluorescent siderophores

Pyoverdins and Azotobactin are known examples of natural fluorescent siderophores that have been isolated from Pseudomonas aeruginosa and Azotobacter vinelandii, res-pectively ° ° . Pyoverdin Pa (171) ° and pyoverdin Pa Til (172) " are members of the pyoverdin family, which are peptide based hexadentate mixed siderophores that consist of a fluorescent chromophore dihydroxyquinoline, which provides a catecholate ligand for Fe(III) coordination in addition to two bidentate hydroxamate ligating groups. 

Two fluorescent siderophore analogs, one based on ferrichrome 173 and the second on ferrioxamine 188, were used to study iron transport in the fungus Ustilago maydis that has an uptake system for ferrichrome but lacks a defined ferrioxamine receptor. Nevertheless, ferrioxamine can be utilized by the fungus albeit at a slower rate. 

The fluorescent siderophore can mimic the disease-suppression ability of the... 

QzHsvFeNijO,, Mr 1041.83, a water-soluble and fluorescing siderophore of the hydroxamate/catechol type R is produced by cultures of Pseudomonas fluo-rescens under iron deficiency conditions. P. is a plant growth substance but also has antifungal activity against Fusarium sp. 

Y.S. Cody and D.C. Gross, Characterization of Pyoverdin PSS, the Fluorescent Siderophore Produced by Pseudomonas syringae pv, syringae, Appl. Env. Microbiol., (1987) 928-934. 

Iron uptake by bacteria at sites of lateral root emergence has been further confirmed using another technique employing 7-nitrobenz-2-oxa-l,3-diazole-desferrioxamine B, which is a derivitized siderophore that becomes fluorescent after it is deferrated (78). In this case, iron uptake from the siderophore ferrox-amine B was a.ssociated primarily with microbially colonized roots, but both plant and iron uptake from this chelate occurred in the regions just behind the root tips. 

E. Bar Ness, Y. Hadar, Y. Chen, and A. Shanzer, Iron uptake by plants from microbial siderophores—a study with 7 nitrobenz-2oxa-1,3-diazole desferrioxamine as fluorescent ferrioxamine B analog. Plant Physiol. 99 1329 (1992). 

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... 

Bultreys A, Gheysen I, Wathelet B, Maraite H, de Hoffman E (2003) High-Performance Liquid Chromatography Analyses of Pyoverdin Siderophores Differentiate among Phyto-pathogenic Fluorescent Pseudomonas Species. Appl Environ Microbiol 69 1143 and unpublished material... 

Meyer JM (2000) Pyoverdines Pigments, Siderophores and Potential Taxonomic Markers of Fluorescent PieMdomonai-Species. Arch Microbiol 174 135... 

Azotobactin is a highly fluorescent hexadentate mixed siderophore containing a pyoverdin-like bidentate ligating chromophore, derived from 2,3-diamino-6,7-dihydroxyquinoline, a hydroxamate and a a-hydroxycarboxylic acid for Fe(in) coordination. ... 

Combining fluorescence spectroscopy with fluorescence microscopy, confocal microscopy could be used to elucidate the pathway of siderophore-mediat iron uptake in the fungus Ustilago maydis, and visualize this pathway by providing unique fluorescent microscopic images. Using these techniques, clear images of two independent iron-uptake mechanisms have become visualized as well as their cellular compartment locahzed. 

Figure 2 Structures of representative catecholate and mixed-ligand siderophores (a) enterobactin (b) parabactin (c) mycobacins (R = various alkyl chains, = R = R = MeorH.R = alkyl chains or H ) (d) fluorescent chromophore of pseudobactins and pyoverdins...

A variety of fluorescent chromopeptide siderophores, termed pseudobactins and pyoverdins, are synthesized by Pseudomonas species. The chromophores, derived from 2,3-diamino-6,7-dihydroxyquinoline (Figure 2(d)), are linked to a peptide chain exhibiting either two hydroxamate groups or one hydroxamate and one a-hydroxycarboxylate group. 

Molybdate binds to the aminochelm siderophore of Azoto-bacter vinelandii, and quenches the fluorescence of attached Ru(bipy)-chromophores, this affording a sensitive probe for the oxoanion. 

The evidence that the ability of fluorescent pseudonomads to suppress plant disease is dependent upon production of siderophores, antibiotics and HCN [129-136] is as follows ... 

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