Skip to main content
NCBI home page
Journal of Bacteriology logoLink to Journal of Bacteriology
. 1983 Dec;156(3):1151–1157. doi: 10.1128/jb.156.3.1151-1157.1983

Characterization of the Na+/H+ antiporter of alkalophilic bacilli in vivo: delta psi-dependent 22Na+ efflux from whole cells.

M L Garcia, A A Guffanti, T A Krulwich
PMCID: PMC217961  PMID: 6315677

Abstract

The Na+/H+ antiporter of Bacillus alcalophilus was studied by measuring 22Na+ efflux from starved, cyanide-inhibited cells which were energized by means of a valinomycin-induced potassium diffusion potential, positive out (delta psi). In the absence of a delta psi, 22Na+ efflux at pH 9.0 was slow and appreciably inhibited by N-ethylmaleimide. Upon imposition of a delta psi, a very rapid rate of 22Na+ efflux occurred. This rapid rate of 22Na+ efflux was competitively inhibited by Li+ and varied directly with the magnitude of the delta psi. Kinetic experiments with B. alcalophilus and alkalophilic Bacillus firmus RAB indicated that the delta psi caused a pronounced increase in the Vmax for 22Na+ efflux. The Km values for Na+ were unaffected by the delta psi. Upon imposition of a delta psi at pH 7.0, a retardation of the slow 22Na+ efflux rate at pH 7.0 was caused by the delta psi. This showed that inactivity of the Na+/H+ antiporter at pH 7.0 was not secondary to a low delta psi generated by respiration at this pH. Indeed, 22Na+ efflux activity appeared to be inhibited by a relatively high internal proton concentration. By contrast, at a constant internal pH, there was little variation in the activity at external pH values from 7.0 to 9.0; at an external pH of 10.0, the rate of 22Na+ efflux declined. This decline at typical pH values for growth may be due to an insufficiency of protons when a diffusion potential rather than respiration is the driving force. Non-alkalophilic mutant strains of B. alcalophilus and B. firmus RAB exhibited a slow rate of 22Na+ efflux which was not enhanced by a delta psi at either pH 7.0 or 9.0.

Full text

PDF
1151

Selected References

These references are in PubMed. This may not be the complete list of references from this article.

  1. Aronson P. S., Nee J., Suhm M. A. Modifier role of internal H+ in activating the Na+-H+ exchanger in renal microvillus membrane vesicles. Nature. 1982 Sep 9;299(5879):161–163. doi: 10.1038/299161a0. [DOI] [PubMed] [Google Scholar]
  2. Aronson P. S., Suhm M. A., Nee J. Interaction of external H+ with the Na+-H+ exchanger in renal microvillus membrane vesicles. J Biol Chem. 1983 Jun 10;258(11):6767–6771. [PubMed] [Google Scholar]
  3. Guffanti A. A., Cohn D. E., Kaback H. R., Krulwich T. A. Relationship between the Na+/H+ antiporter and Na+/substrate symport in Bacillus alcalophilus. Proc Natl Acad Sci U S A. 1981 Mar;78(3):1481–1484. doi: 10.1073/pnas.78.3.1481. [DOI] [PMC free article] [PubMed] [Google Scholar]
  4. Guffanti A. A., Susman P., Blanco R., Krulwich T. A. The protonmotive force and alpha-aminoisobutyric acid transport in an obligately alkalophilic bacterium. J Biol Chem. 1978 Feb 10;253(3):708–715. [PubMed] [Google Scholar]
  5. Haines T. H. Anionic lipid headgroups as a proton-conducting pathway along the surface of membranes: a hypothesis. Proc Natl Acad Sci U S A. 1983 Jan;80(1):160–164. doi: 10.1073/pnas.80.1.160. [DOI] [PMC free article] [PubMed] [Google Scholar]
  6. Kitada M., Guffanti A. A., Krulwich T. A. Bioenergetic properties and viability of alkalophilic Bacillus firmus RAB as a function of pH and Na+ contents of the incubation medium. J Bacteriol. 1982 Dec;152(3):1096–1104. doi: 10.1128/jb.152.3.1096-1104.1982. [DOI] [PMC free article] [PubMed] [Google Scholar]
  7. Krulwich T. A., Guffanti A. A., Bornstein R. F., Hoffstein J. A sodium requirement for growth, solute transport, and pH homeostasis in Bacillus firmus RAB. J Biol Chem. 1982 Feb 25;257(4):1885–1889. [PubMed] [Google Scholar]
  8. Krulwich T. A., Mandel K. G., Bornstein R. F., Guffanti A. A. A non-alkalophilic mutant of Bacillus alcalophilus lacks the Na+/H+ antiporter. Biochem Biophys Res Commun. 1979 Nov 14;91(1):58–62. doi: 10.1016/0006-291x(79)90582-5. [DOI] [PubMed] [Google Scholar]
  9. Krulwich T. A. Na+/H+ antiporters. Biochim Biophys Acta. 1983 Dec 30;726(4):245–264. doi: 10.1016/0304-4173(83)90011-3. [DOI] [PubMed] [Google Scholar]
  10. Lewis R. J., Krulwich T. A., Reynafarje B., Lehninger A. L. Respiration-dependent proton translocation in alkalophilic Bacillus firmus RAB and its non-alkalophilic mutant derivative. J Biol Chem. 1983 Feb 25;258(4):2109–2111. [PubMed] [Google Scholar]
  11. Mandel K. G., Guffanti A. A., Krulwich T. A. Monovalent cation/proton antiporters in membrane vesicles from Bacillus alcalophilus. J Biol Chem. 1980 Aug 10;255(15):7391–7396. [PubMed] [Google Scholar]
  12. Schuldiner S., Kaback H. R. Membrane potential and active transport in membrane vesicles from Escherichia coli. Biochemistry. 1975 Dec 16;14(25):5451–5461. doi: 10.1021/bi00696a011. [DOI] [PubMed] [Google Scholar]
  13. Tokuda H., Kaback H. R. Sodium-dependent methyl 1-thio-beta-D-galactopyranoside transport in membrane vesicles isolated from Salmonella typhimurium. Biochemistry. 1977 May 17;16(10):2130–2136. doi: 10.1021/bi00629a013. [DOI] [PubMed] [Google Scholar]

Articles from Journal of Bacteriology are provided here courtesy of American Society for Microbiology (ASM)

RESOURCES