Sodium ATPase and sodium/proton antiporter are not obligatory for sodium homeostasis of Enterococcus hirae at acid pH |
| |
Authors: | Ikegami M Takahashi H Igarashi K Kakinuma Y |
| |
Institution: | Faculty of Pharmaceutical Sciences, Chiba University, Japan. |
| |
Abstract: | Enterococcus hirae grows in a broad pH range from 5 to 11. An E. hirae mutant 7683 lacking the activities of two sodium pumps, Na+-ATPase and Na+/H+ antiporter, does not grow in high Na+ medium at pH above 7.5. We found that 7683 grew normally in high Na+ medium at pH 5.5. Although an energy-dependent sodium extrusion at pH 5.5 was missing, the intracellular levels of Na+ and K+ were normal in this mutant. The Na+ influx rates of 7683 and two other strains at pH 5.5 were much slower than those at pH 7.5. These results suggest that Na+ elimination of this bacterium at acid pH is achieved by a decrease in Na+ entry and a normal K+ uptake. |
| |
Keywords: | |
本文献已被 PubMed 等数据库收录! |
|