Iron acquisition during growth in an iron-deficient medium by Rhizobium sp. isolated from Cicer arietinum

A catechol-type siderophore was produced extracellularly by Rhizobium sp. strain BICC 651 isolated from Cicer arietinum during growth in iron-deficient medium. Production of the siderophore was fully repressed in the presence of 50 micromolar Fe3+. The siderophore was purified and characterized as c...

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Bibliographic Details
Published in:Microbiology (Society for General Microbiology) 1994-10, Vol.140 (10), p.2811-2820
Main Authors: Roy, N, Bhattacharyya, P, Chakrabartty, P.K
Format: Article
Language:English
Subjects:
bacterial proteins
Bacteriology
Biological and medical sciences
biosynthesis
cell membranes
Cicer arietinum
enzyme activity
ferrireductase
Fundamental and applied biological sciences. Psychology
growth
ion transport
iron
Microbiology
nutrient deficiencies
outer membrane proteins
oxidoreductases
Permeability, membrane transport, intracellular transport
Rhizobium
siderophores
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Summary:A catechol-type siderophore was produced extracellularly by Rhizobium sp. strain BICC 651 isolated from Cicer arietinum during growth in iron-deficient medium. Production of the siderophore was fully repressed in the presence of 50 micromolar Fe3+. The siderophore was purified and characterized as containing 2,3-dihydroxybenzoic acid (DHBA) as the core compound and threonine as its conjugate. The siderophore was able to reverse growth inhibition of the strain induced by ethylenediamine-di(o-hydroxyphenyl-acetic acid) (EDDA). A high-affinity iron-transport system capable of transporting 59Fe-siderophore complex was also induced in Rhizobium BICC 651 grown under iron deficiency. Two protein bands of molecular masses 76 and 82 kDa were also inductively synthesized in the outer membrane of the cells. A partially purified ferrireductase enzyme of Rhizobium BICC 651 catalysed reductive release of iron from the ferric chelate of DHBA. The enzyme had a Km of 0.3 millimole for ferri-DHBA, was constitutive in nature, and was present in the cytosolic fraction during growth under both iron-deficient and iron-sufficient conditions. The enzyme occurred as two isoenzymes with RF values of 0.48 and 0.51, respectively, in a nondenaturing polyacrylamide gel.
ISSN:1350-0872
1465-2080
DOI:10.1099/00221287-140-10-2811