Presence of Na+-stimulated P-type ATPase in the membrane of a facultatively anaerobic alkaliphile, Exiguobacterium aurantiacum.
It was found that a facultatively anaerobic alkaliphile, Exiguobacterium aurantiacum, possesses a membrane-bound ATPase, which was activated specifically by Na+. The Na+-stimulated ATPase activity reached a maximum value at 200 mM NaCl. In the presence of 200 mM NaCl, the activity was drastically reduced by vanadate, a potent inhibitor of P-type ATPase, with a half-maximal inhibition at 1 microM. Incubation of the membranes with [gamma-32P]ATP followed by acidic lithium dodecyl sulfate-polyacrylamide gel electrophoresis demonstrated the existence of two phosphorylated intermediates with apparent molecular masses of 60 and 100 kDa. Only phosphorylation of the 100-kDa polypeptide was inhibited by vanadate. The membrane extract containing Na+-stimulated ATPase, when reconstituted into soybean phospholipid vesicles, exhibited 22Na+ transport by the addition of ATP, which was inhibited by vanadate and gramicidin. It is likely that the Na+-stimulated ATPase belongs to P-type and is involved in Na+ transport.
Koyama
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Department of Chemistry, Faculty of Science, Chiba University, Yayoi, Inage-ku, Chiba 263-8522, Japan.
D000251:Adenosine Triphosphatases / Q000187:drug effects / Q000378:metabolism*; D001421:Bacteria, Anaerobic / Q000201:enzymology* / Q000254:growth & development; D001425:Bacterial Outer Membrane Proteins / Q000187:drug effects / Q000378:metabolism*; D001426:Bacterial Proteins / Q000378:metabolism*; D027682:Cation Transport Proteins; D004789:Enzyme Activation; D006096:Gramicidin / Q000494:pharmacology; D012965:Sodium Chloride / Q000494:pharmacology; D014638:Vanadates / Q000494:pharmacology
D001425:Bacterial Outer Membrane Proteins; D001426:Bacterial Proteins; D027682:Cation Transport Proteins; D006096:Gramicidin; D014638:Vanadates; D012965:Sodium Chloride; D000251:Adenosine Triphosphatases; C021838:sodium-translocating ATPase