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Sodium-stimulated ATPase in Streptococcus faecalis.
Journal of Bacteriology
|June 1, 1984
Summary
This study investigated Na+-stimulated ATPase activity in Streptococcus faecalis, finding that decreased sodium ion (Na+) concentration impacts enzyme and transport activity. The research suggests ATPase mediates Na+ movement and its level increases with proton motive force dissipation.
Area of Science:
- Microbiology
- Biochemistry
- Cellular Physiology
Background:
- Proton motive force (PMF) is crucial for cellular energy generation.
- Sodium ion (Na+) transport plays a vital role in bacterial physiology.
- Understanding the regulation of Na+-stimulated ATPase is key to bacterial energy metabolism.
Purpose of the Study:
- To investigate the role of Na+-stimulated ATPase in Streptococcus faecalis.
- To determine the relationship between Na+ concentration, proton motive force, and ATPase activity.
- To elucidate the mechanism of Na+ movement in bacteria.
Main Methods:
- Measurement of Na+-stimulated ATPase activity in membrane vesicles.
- Analysis of Na+ transport in whole cells and membrane vesicles.
- Growth of Streptococcus faecalis in media with varying Na+ concentrations.
- Assessment of enzyme activity under conditions of altered proton motive force.
Main Results:
- A mutant defective in PMF generation exhibited high Na+-stimulated ATPase activity.
- ATPase activity correlated directly with Na+ concentration in the growth medium.
- Na+ transport activity in both whole cells and vesicles mirrored ATPase activity.
- Wild-type strains showed lower ATPase and Na+ extrusion, but elevated levels when PMF was dissipated.
Conclusions:
- Na+-stimulated ATPase likely mediates Na+ movement in Streptococcus faecalis.
- The level of ATPase is regulated by the dissipation of proton motive force.
- Bacterial energy metabolism is intricately linked to ion transport and ATPase activity.