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Inositol polyphosphate-mediated iron transport in Pseudomonas aeruginosa
Abstract:
It has previously been shown that myo-inositol hexakisphosphate (myo-InsP6) mediates iron transport into Pseudomonas aeruginosa and overcomes iron-dependent growth inhibition. In this study, the iron transport properties of myo-inositol trisphosphate and tetrakisphosphate regio-isomers were studied. Pseudomonas aeruginosa accumulated iron (III) at similar rates whether complexed with myo-Ins(1,2,3)P3 or myo-InsP6. Iron accumulation from other compounds, notably D/L myo-Ins(1,2,4,5)P4 and another inositol trisphosphate regio-isomer, D-myo-Ins(1,4,5)P3, was dramatically increased. Iron transport profiles from myo-InsP6 into mutants lacking the outer membrane porins oprF, oprD and oprP were similar to the wild-type, indicating that these porins are not involved in the transport process. The rates of reduction of iron (III) to iron (II) complexed to any of the compounds by a Ps. aeruginosa cell lysate were similar, suggesting that a reductive mechanism is not the rate-determining step.
Insights
Myo-inositol phosphates facilitate iron transport in Pseudomonas aeruginosa. Specific inositol phosphates, like myo-inositol trisphosphate and tetrakisphosphate, significantly enhance iron accumulation, aiding bacterial growth.
Area of Science:
- Microbiology
- Biochemistry
- Molecular Biology
Background:
- Myo-inositol hexakisphosphate (myo-InsP6) is known to mediate iron transport in Pseudomonas aeruginosa.
- Iron availability is crucial for bacterial growth and overcoming iron-dependent growth inhibition.
Purpose of the Study:
- To investigate the iron transport properties of myo-inositol trisphosphate and tetrakisphosphate regio-isomers in Pseudomonas aeruginosa.
- To determine the role of specific inositol phosphates in iron uptake and bacterial iron metabolism.
Main Methods:
- Studied iron (III) accumulation by Pseudomonas aeruginosa complexed with various myo-inositol phosphates.
- Analyzed iron transport in wild-type and outer membrane porin mutants (oprF, oprD, oprP).
- Assessed the rate of iron reduction by Pseudomonas aeruginosa cell lysate.
Main Results:
- Pseudomonas aeruginosa showed similar iron (III) accumulation rates with myo-Ins(1,2,3)P3 and myo-InsP6.
- Iron accumulation was dramatically increased with D/L myo-Ins(1,2,4,5)P4 and D-myo-Ins(1,4,5)P3.
- Outer membrane porins (oprF, oprD, oprP) were not involved in myo-InsP6-mediated iron transport.
- Iron reduction by cell lysate was not the rate-determining step for iron transport.
Conclusions:
- Specific regio-isomers of myo-inositol trisphosphate and tetrakisphosphate significantly enhance iron accumulation in Pseudomonas aeruginosa.
- Outer membrane porins are not essential for myo-inositol hexakisphosphate-mediated iron transport.
- The rate-limiting step in iron transport is not a reductive mechanism.