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Updated: Jul 14, 2026
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Screening for Thermotoga maritima Membrane-Bound Pyrophosphatase Inhibitors
Published on: November 23, 2019
Na+-pyrophosphatase: a novel primary sodium pump
Anssi M Malinen1, Georgiy A Belogurov, Alexander A Baykov
1Department of Biochemistry and Food Chemistry, University of Turku, FIN-20014 Turku, Finland.
Biochemistry
|July 4, 2007
Summary
This study reveals that bacterial membrane pyrophosphatases (PPases) function as sodium (Na+) pumps, not proton (H+) pumps. These Na+-dependent PPases are electrogenic, utilizing pyrophosphate hydrolysis to transport Na+ across membranes.
Area of Science:
- Biochemistry
- Molecular Biology
- Microbiology
Background:
- Membrane-bound pyrophosphatase (PPase) is traditionally thought to transport protons (H+) coupled to pyrophosphate (PPi) hydrolysis.
- Recent studies suggest alternative transport mechanisms for PPases.
Purpose of the Study:
- To investigate the ion transport mechanism of newly isolated bacterial membrane PPases.
- To determine if these PPases transport H+ or other cations, such as Na+.
Main Methods:
- Isolated and characterized membrane PPases from Methanosarcina mazei (Mm-PPase), Moorella thermoacetica, and Thermotoga maritima.
- Utilized Escherichia coli inner membrane vesicles (IMV) for transport assays.
- Performed kinetic analysis, ionophore treatments, and membrane potential measurements.
Main Results:
- Three bacterial PPases demonstrated Na+ transport, not H+ transport, into IMVs.
- PPase activity showed an absolute requirement for Na+ and was enhanced by K+.
- Kinetic analysis of Mm-PPase revealed two Na+ binding sites, with K+ modulating Na+ affinity and catalytic efficiency.
- PPi-driven Na+ transport generated a positive inside membrane potential, confirming electrogenic Na+ pumping.
Conclusions:
- Bacterial membrane PPases function as electrogenic Na+ pumps, challenging the long-held H+ transport model.
- Phylogenetic analysis suggests ancient gene duplication led to the divergence of Na+- and H+-PPases.
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