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Updated: May 6, 2026
Author Spotlight: Quantifying Siderophores and Pyochelin for Infection Control
Published on: March 15, 2024
Deciphering protein dynamics of the siderophore pyoverdine pathway in Pseudomonas aeruginosa
Laurent Guillon1, Stephan Altenburger, Peter L Graumann
1UMR 7242, Université de Strasbourg-CNRS, Strasbourg, France.
Abstract:
Pseudomonas aeruginosa produces the siderophore, pyoverdine (PVD), to obtain iron. Siderophore pathways involve complex mechanisms, and the machineries responsible for biosynthesis, secretion and uptake of the ferri-siderophore span both membranes of Gram-negative bacteria. Most proteins involved in the PVD pathway have been identified and characterized but the way the system functions as a whole remains unknown. By generating strains expressing fluorescent fusion proteins, we show that most of the proteins are homogeneously distributed throughout the bacterial cell. We also studied the dynamics of these proteins using fluorescence recovery after photobleaching (FRAP). This led to the first diffusion coefficients ever determined in P. aeruginosa. Cytoplasmic and periplamic diffusion appeared to be slower than in Escherichia coli but membrane proteins seemed to behave similarly in the two species. The diffusion of cytoplasmic and periplasmic tagged proteins involved in the PVD pathway was dependent on the interaction network to which they belong. Importantly, the TonB protein, motor of the PVD-Fe uptake process, was mostly immobile but its mobility increased substantially in the presence of PVD-Fe.
Insights
This study reveals how Pseudomonas aeruginosa utilizes pyoverdine (PVD) for iron uptake. Protein dynamics and diffusion within the bacterial cell were measured, showing PVD-Fe influences TonB protein mobility.
Area of Science:
- Microbiology
- Bacterial Physiology
- Molecular Biology
Background:
- Pseudomonas aeruginosa requires iron for growth and utilizes the siderophore pyoverdine (PVD) for iron acquisition.
- The PVD pathway involves complex protein machinery spanning bacterial membranes, but its integrated function remains unclear.
- Understanding protein dynamics is crucial for elucidating the complete PVD system's mechanism.
Purpose of the Study:
- To investigate the spatial distribution and dynamics of proteins involved in the PVD pathway in Pseudomonas aeruginosa.
- To determine the diffusion coefficients of these proteins within the bacterial cell.
- To elucidate the role of protein interactions and environmental factors, like PVD-Fe, in pathway function.
Main Methods:
- Construction of Pseudomonas aeruginosa strains expressing fluorescent fusion proteins for key PVD pathway components.
- Microscopy techniques to assess homogeneous protein distribution.
- Fluorescence Recovery After Photobleaching (FRAP) to measure protein diffusion coefficients and dynamics.
Main Results:
- Most PVD pathway proteins are homogeneously distributed within the bacterial cell.
- First determination of diffusion coefficients for cytoplasmic and periplasmic proteins in P. aeruginosa, showing slower diffusion compared to E. coli.
- TonB protein, essential for iron uptake, exhibited increased mobility upon binding PVD-Fe.
Conclusions:
- Protein diffusion within P. aeruginosa is influenced by interaction networks and cellular localization.
- The TonB protein's dynamics are regulated by its substrate, suggesting a mechanism for controlling iron uptake.
- This study provides novel insights into the functional dynamics of the PVD siderophore system in Gram-negative bacteria.
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