A siderophore from Pseudomonas putida type A1: structural and biological characterization

Boopathi, E and Rao, Sankara K (1999) A siderophore from Pseudomonas putida type A1: structural and biological characterization. In: Biochimica et Biophysica Acta (BBA), 1435 (1-2). pp. 30-40.

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Abstract

A siderophore from a root-colonizing, plant-beneficial flourescent Pseudomonas (P. putida type A1) isolated from chickpea rhizosphere was studied. Culture conditions required for optimal production of the chromophore by the organism were standardized. The compound was purified by gel filtration, ion exchange and RP-HPLC chromatographic procedures. The purified compound exhibited siderophore activity for P. putida and antifungal activity on phytopathogens, Fusarium oxysporum f. sp. ciceri and Helminthosporium oryzae. Growth inhibition of the pathogens was observed under iron-deficient conditions. Complete acid hydrolysis of the compound revealed that it is a peptide containing Asx, Thr, Glx, Val, His, Lys, Ser and Gly. Spectral analysis revealed that it contains hydroxyquinoline-based chromophore in addition to an aromatic residue and the molecular weight of the compound was 1.5 kDa. EPR analysis of the peptide-chromophore-iron complex showed that the compound binds to iron and the bound iron was in the $Fe^{3+}$ oxidation state having a high spin $d^5$ system. The peptide-chromophore-iron complex takes a turn structure in solution as shown by circular dichroism spectroscopy, a feature which was hitherto not known for other siderophores. The siderophore studied here is unique in this respect but otherwise strikingly similar to other pseudobactin-type siderophores of plant growth-promoting and plant-deleterious pseudomonads. The possible functional significance of the compound is discussed in relation to the secondary structure described earlier for siderophores.

Item Type:	Journal Article
Publication:	Biochimica et Biophysica Acta (BBA)
Publisher:	Elsevier
Additional Information:	Copyright of this article belongs to Elsevier.
Keywords:	Siderophorenext term;Purification;Amino acid;Antifungal activity;Characterization;Pseudomonas putida
Department/Centre:	Division of Biological Sciences > Biochemistry
Date Deposited:	28 Sep 2007
Last Modified:	19 Sep 2010 04:39
URI:	http://eprints.iisc.ac.in/id/eprint/11966

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