Siderophore-mediated uptake of Fe3+ by the plant growth-stimulating Pseudomonas putida strain WCS358 and by other rhizosphere microorganisms.
Under iron-limited conditions, Pseudomonas putida WCS358 produces a siderophore, pseudobactin 358, which is essential for the plant growth-stimulating ability of this strain. Cells of strain WCS358, provided that they have been grown under Fe3+ limitation, take up 55Fe3+ from the 55Fe3+-labeled pseudobactin 358 complex with Km and Vmax values of 0.23 microM and 0.14 nmol/mg of cell dry weight per min, respectively. Uptake experiments with cells treated with various metabolic inhibitors showed that this Fe3+ uptake process was dependent on the proton motive force. Furthermore, strain WCS358 was shown to be able to take up Fe3+ complexed to the siderophore of another plant-beneficial P. fluorescens strain, WCS374. The tested pathogenic rhizobacteria and rhizofungi were neither able to grow on Fe3+-deficient medium in the presence of pseudobactin 358 nor able to take up 55Fe3+ from 55Fe3+-pseudobactin 358. The same applies for three cyanide-producing Pseudomonas strains which are supposed to be representatives of the minor pathogens. These results indicate that the extraordinary ability of strain WCS358 to compete efficiently for Fe3+ is based on the fact that the pathogenic and deleterious rhizosphere microorganisms, in contrast to strain WCS358 itself, are not able to take up Fe3+ from Fe3+-pseudobactin 358 complexes.
de Weger
L A
LA
Department of Plant Molecular Biology, Leiden University, The Netherlands.
van Arendonk
J J
JJ
Recourt
K
K
van der Hofstad
G A
GA
Weisbeek
P J
PJ
Lugtenberg
B
B
D001693:Biological Transport, Active; D005290:Ferric Compounds / Q000378:metabolism*; D007502:Iron Chelating Agents / Q000502:physiology*; D009842:Oligopeptides / Q000502:physiology; D011549:Pseudomonas / Q000378:metabolism*; D017262:Siderophores; D013559:Symbiosis
D005290:Ferric Compounds; D007502:Iron Chelating Agents; D009842:Oligopeptides; D017262:Siderophores; C033038:pseudobactin