Biomaterial Database

ATP-driven sodium pump in Streptococcus faecalis. 1982

D L Heefner, and F M Harold

Sodium extrusion by bacteria is generally attributed to secondary antiport of Na+ for H+ energized by the proton circulation. Streptococcus faecalis is an exception, in that sodium expulsion from intact cells requires the generation of ATP but does not depend on the protonmotive force. Unfortunately, studies with everted membrane vesicles failed to reveal the expected sodium pump; instead, the vesicles contained a conventional secondary Na+/H+ antiporter. We report here that everted membrane vesicles prepared in the presence of protease inhibitors retain an ATP-driven sodium transport system. The evidence includes the findings that (i) accumulation of 22Na+ by these vesicles is resistant to reagents that dissipate the protonmotive force but requires ATP and (ii) the vesicles contain a sodium-stimulated ATPase that is distinct from F1F0 ATPase, and whose presence is correlated with sodium transport activity. Sodium movements appear to be electroneutral and are accompanied by movement of H+ in the opposite direction. When membranes are incubated in the absence of protease inhibitors, a secondary Na+/H+ antiport activity emerges, possibly by degradation of the sodium pump. We suggest that S. faecalis expels Na+ by means of an ATP-driven primary transport system that mediates exchange of Na+ for H+. The Na+/H+ antiporter seen in earlier membrane preparation is an artefact of proteolytic degradation.

UI	MeSH Term	Description	Entries
D002352	Carrier Proteins	Proteins that bind or transport specific substances in the blood, within the cell, or across cell membranes.	Binding Proteins,Carrier Protein,Transport Protein,Transport Proteins,Binding Protein,Protein, Carrier,Proteins, Carrier
D002462	Cell Membrane	The lipid- and protein-containing, selectively permeable membrane that surrounds the cytoplasm in prokaryotic and eukaryotic cells.	Plasma Membrane,Cytoplasmic Membrane,Cell Membranes,Cytoplasmic Membranes,Membrane, Cell,Membrane, Cytoplasmic,Membrane, Plasma,Membranes, Cell,Membranes, Cytoplasmic,Membranes, Plasma,Plasma Membranes
D002474	Cell-Free System	A fractionated cell extract that maintains a biological function. A subcellular fraction isolated by ultracentrifugation or other separation techniques must first be isolated so that a process can be studied free from all of the complex side reactions that occur in a cell. The cell-free system is therefore widely used in cell biology. (From Alberts et al., Molecular Biology of the Cell, 2d ed, p166)	Cellfree System,Cell Free System,Cell-Free Systems,Cellfree Systems,System, Cell-Free,System, Cellfree,Systems, Cell-Free,Systems, Cellfree
D000251	Adenosine Triphosphatases	A group of enzymes which catalyze the hydrolysis of ATP. The hydrolysis reaction is usually coupled with another function such as transporting Ca(2+) across a membrane. These enzymes may be dependent on Ca(2+), Mg(2+), anions, H+, or DNA.	ATPases,Adenosinetriphosphatase,ATPase,ATPase, DNA-Dependent,Adenosine Triphosphatase,DNA-Dependent ATPase,DNA-Dependent Adenosinetriphosphatases,ATPase, DNA Dependent,Adenosinetriphosphatases, DNA-Dependent,DNA Dependent ATPase,DNA Dependent Adenosinetriphosphatases,Triphosphatase, Adenosine
D001426	Bacterial Proteins	Proteins found in any species of bacterium.	Bacterial Gene Products,Bacterial Gene Proteins,Gene Products, Bacterial,Bacterial Gene Product,Bacterial Gene Protein,Bacterial Protein,Gene Product, Bacterial,Gene Protein, Bacterial,Gene Proteins, Bacterial,Protein, Bacterial,Proteins, Bacterial
D001693	Biological Transport, Active	The movement of materials across cell membranes and epithelial layers against an electrochemical gradient, requiring the expenditure of metabolic energy.	Active Transport,Uphill Transport,Active Biological Transport,Biologic Transport, Active,Transport, Active Biological,Active Biologic Transport,Transport, Active,Transport, Active Biologic,Transport, Uphill
D012964	Sodium	A member of the alkali group of metals. It has the atomic symbol Na, atomic number 11, and atomic weight 23.	Sodium Ion Level,Sodium-23,Ion Level, Sodium,Level, Sodium Ion,Sodium 23
D013293	Enterococcus faecalis	A species of gram-positive, coccoid bacteria commonly isolated from clinical specimens and the human intestinal tract. Most strains are nonhemolytic.	Streptococcus Group D,Streptococcus faecalis
D017923	Sodium-Hydrogen Exchangers	A family of plasma membrane exchange glycoprotein antiporters that transport sodium ions and protons across lipid bilayers. They have critical functions in intracellular pH regulation, cell volume regulation, and cellular response to many different hormones and mitogens.	Na(+)-H(+)-Antiporter,Na(+)-H(+)-Exchanger,Sodium-Hydrogen Antiporter,Na(+)-H(+)-Antiporters,Na(+)-H(+)-Exchangers,SLC9 Na(+)-H(+) Exchangers,SLC9 Protein Family,SLC9 Proteins,SLC9-NHE Protein Family,Sodium-Hydrogen Antiporters,Sodium-Hydrogen Exchanger,Sodium-Proton Antiporter,Sodium-Proton Antiporters,Solute Carrier 9 Protein Family,Solute Carrier 9 Proteins,Antiporter, Sodium-Hydrogen,Antiporter, Sodium-Proton,Antiporters, Sodium-Hydrogen,Antiporters, Sodium-Proton,Exchanger, Sodium-Hydrogen,Exchangers, Sodium-Hydrogen,Protein Family, SLC9,Protein Family, SLC9-NHE,SLC9 NHE Protein Family,Sodium Hydrogen Antiporter,Sodium Hydrogen Antiporters,Sodium Hydrogen Exchanger,Sodium Hydrogen Exchangers,Sodium Proton Antiporter,Sodium Proton Antiporters