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FpvA receptor involvement in pyoverdine biosynthesis in Pseudomonas aeruginosa
Jiangsheng Shen1, Allison Meldrum, Keith Poole
1Department of Microbiology and Immunology, Queen's University, Kingston, Ontario, Canada K7L 3N6.
Abstract:
Alignment of the Pseudomonas aeruginosa ferric pyoverdine receptor, FpvA, with similar ferric-siderophore receptors revealed that the mature protein carries an extension of ca. 70 amino acids at its N terminus, an extension shared by the ferric pseudobactin receptors of P. putida. Deletion of fpvA from the chromosome of P. aeruginosa reduced pyoverdine production in this organism, as a result of a decline in expression of genes (e.g., pvdD) associated with the biosynthesis of the pyoverdine peptide moiety. Wild-type fpvA restored pvd expression in the mutant, thereby complementing its pyoverdine deficiency, although a deletion derivative of fpvA encoding a receptor lacking the N terminus of the mature protein did not. The truncated receptor was, however, functional in pyoverdine-mediated iron uptake, as evidenced by its ability to promote pyoverdine-dependent growth in an iron-restricted medium. These data are consistent with the idea that the N-terminal extension plays a role in FpvA-mediated pyoverdine biosynthesis in P. aeruginosa.
Insights
The Pseudomonas aeruginosa ferric pyoverdine receptor (FpvA) has an N-terminal extension crucial for pyoverdine biosynthesis. This extension is not required for iron uptake, indicating distinct functional roles.
Area of Science:
- Microbiology
- Molecular Biology
- Biochemistry
Background:
- Pseudomonas aeruginosa utilizes pyoverdine, a siderophore, for iron acquisition.
- Ferric siderophore receptors, like FpvA, are essential for importing iron-bound siderophores.
- Structural similarities exist between FpvA and other ferric siderophore receptors.
Purpose of the Study:
- To investigate the role of the N-terminal extension of FpvA in pyoverdine biosynthesis and iron uptake.
- To determine the functional significance of the FpvA N-terminal region in Pseudomonas aeruginosa.
Main Methods:
- Comparative sequence alignment of FpvA with related receptors.
- Gene deletion studies to analyze the function of fpvA.
- Complementation assays using wild-type and truncated fpvA.
- Growth assays under iron-restricted conditions.
Main Results:
- FpvA possesses a conserved N-terminal extension of approximately 70 amino acids.
- Deletion of fpvA significantly reduced pyoverdine production and associated gene expression (e.g., pvdD).
- Wild-type FpvA restored pyoverdine production, but a truncated FpvA lacking the N-terminus did not.
- The truncated FpvA remained functional for pyoverdine-mediated iron uptake and bacterial growth.
Conclusions:
- The N-terminal extension of FpvA is essential for regulating pyoverdine biosynthesis in Pseudomonas aeruginosa.
- Distinct domains of FpvA mediate biosynthesis regulation and iron uptake functions.
- This finding highlights the complex regulatory mechanisms of siderophore systems in bacteria.