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Proton/sodium ion antiport in Escherichia coli
The Biochemical Journal
|October 1, 1974
Summary
Escherichia coli uses sodium ions (Na+) to re-establish proton (H+) balance across its plasma membrane. A Na+/H+ antiport system facilitates this electroneutral process, crucial for bacterial homeostasis.
Area of Science:
- Microbiology
- Cellular Physiology
- Biochemistry
Background:
- Anaerobic Escherichia coli suspensions exhibit outward translocation of protons (H+) across the plasma membrane following a respiratory pulse.
- Re-equilibration of proton gradients is essential for maintaining cellular homeostasis.
Purpose of the Study:
- To investigate the mechanism of proton (H+) re-equilibration in anaerobic Escherichia coli.
- To identify the role of sodium ions (Na+) in catalyzing proton re-equilibration.
Main Methods:
- Utilized anaerobic suspensions of Escherichia coli.
- Observed the effects of respiratory pulses and sudden addition of sodium (Na+) salts on ion translocation across the plasma membrane.
Main Results:
- Sudden addition of Na+ salt induced effective outward translocation of H+ via an electroneutral process.
- Demonstrated that Na+ catalyzes the re-equilibration of H+ gradients.
Conclusions:
- Escherichia coli possesses a plasma membrane Na+/H+ antiport system.
- This system normally translocates Na+ outwards, driven by an inwardly directed H+-activity gradient.