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Multiple outer membrane receptors for uptake of ferric pseudobactins in Pseudomonas putida WCS358
1Department of Molecular Cell Biology, Utrecht University, The Netherlands.
Abstract:
Under iron limitation Pseudomonas putida WCS358 produces a fluorescent siderophore, pseudobactin 358, which, after complexing iron, is transported back into the cell via the specific outer membrane receptor PupA. In addition, this strain has the capacity to take up iron via a large variety of siderophores produced by other fluorescent pseudomonads. Putative receptor genes for such siderophores were identified in the chromosome of strain WCS358 by PCR using primers matching two domains conserved in four ferric pseudobactin receptors, including PupA. Eleven amplification products within the expected size range were obtained. Sequence analysis confirmed that the products were derived from genes encoding outer membrane receptors. Two complete receptor genes were isolated from a genomic library of P. putida WCS358. Both protein products are involved in the transport of a limited number of specific ferric pseudobactins. These results indicate that the ability of P. putida WCS358 to exploit many different heterologous pseudobactins is related to the presence of multiple outer membrane receptor proteins.
Insights
Pseudomonas putida WCS358 utilizes multiple outer membrane receptors to import iron bound to various siderophores. This allows the bacterium to efficiently acquire essential iron from diverse sources, enhancing its survival under iron-limited conditions.
Area of Science:
- Microbiology
- Biochemistry
Background:
- Pseudomonas putida WCS358 synthesizes pseudobactin 358 for iron uptake via the PupA receptor.
- The strain can also utilize siderophores from other fluorescent pseudomonads.
Purpose of the Study:
- To identify and characterize the outer membrane receptors responsible for heterologous siderophore uptake in P. putida WCS358.
Main Methods:
- Polymerase chain reaction (PCR) with conserved domain primers.
- Sequence analysis of amplification products.
- Genomic library screening and isolation of receptor genes.
Main Results:
- Eleven putative outer membrane receptor genes were identified.
- Two complete receptor genes were isolated and characterized.
- These receptors facilitate the uptake of specific, but varied, ferric pseudobactins.
Conclusions:
- P. putida WCS358 possesses multiple outer membrane receptors for heterologous siderophore-mediated iron uptake.
- This expands the bacterium's ability to acquire iron from diverse environmental sources.