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The pyocin Sa receptor of Pseudomonas aeruginosa is associated with ferripyoverdin uptake
A W Smith1, P H Hirst, K Hughes
1Pharmaceutical Sciences Institute, Aston University, Birmingham, United Kingdom.
Abstract:
We have used Tn5 mutagenesis to obtain a mutant resistant to pyocin Sa. When grown in iron-deficient succinate medium this mutant lacked an 85-kDa iron-regulated outer membrane protein (IROMP), and expression of a 75-kDa IROMP was increased compared with that in the parent strain. The mutant was deficient in pyoverdin biosynthesis and showed a 95% decrease in transport of ferripyoverdin purified from the parent strain, suggesting that the 85-kDa IROMP is the specific receptor for ferripyoverdin and pyocin Sa. The mutant compensated for the deficiency in pyoverdin biosynthesis and transport by exhibiting a fourfold increase in ferripyochelin transport. The low-level transport of ferripyoverdin in the Sa-resistant mutant, which extended to heterologous pyoverdins from other strains, suggests that Pseudomonas aeruginosa has a second ferripyoverdin uptake system of lower affinity and broader specificity.
Insights
Researchers identified a specific outer membrane protein as the receptor for pyocin Sa and ferripyoverdin in Pseudomonas aeruginosa. A mutant lacking this protein showed altered iron uptake and increased ferripyochelin transport.
Area of Science:
- Microbiology
- Molecular Biology
- Biochemistry
Background:
- Pseudomonas aeruginosa utilizes iron-regulated outer membrane proteins (IROMPs) for nutrient acquisition and defense.
- Pyocins and pyoverdins are crucial for iron uptake and inter-bacterial competition in P. aeruginosa.
Purpose of the Study:
- To identify the specific outer membrane protein responsible for pyocin Sa and ferripyoverdin uptake.
- To investigate the role of IROMPs in iron transport and siderophore utilization in P. aeruginosa.
Main Methods:
- Tn5 mutagenesis was employed to generate a pyocin Sa-resistant mutant.
- Iron-deficient growth conditions and succinate medium were used for protein expression analysis.
- Transport assays for ferripyoverdin and ferripyochelin were performed.
Main Results:
- The pyocin Sa-resistant mutant lacked an 85-kDa IROMP and showed increased expression of a 75-kDa IROMP.
- The mutant exhibited a 95% decrease in ferripyoverdin transport, indicating the 85-kDa IROMP is the ferripyoverdin receptor.
- A fourfold increase in ferripyochelin transport was observed, suggesting compensatory mechanisms for iron acquisition.
Conclusions:
- The 85-kDa IROMP is identified as the specific receptor for pyocin Sa and ferripyoverdin in P. aeruginosa.
- P. aeruginosa possesses a secondary, lower-affinity ferripyoverdin uptake system with broader specificity.