Abstract
The nhaA gene of Escherichia coli, which encodes a pH-activated Na+/H+ antiporter, has been modified; six of its eight histidine codons were mutated to arginine codons by site-directed mutagenesis, yielding the mutations H254R-H257R (a double mutant), H226R, H39R, H244R, and H319R. In addition a deletion (delta nhaA1-14) lacking the remaining two histidines, His-3 and His-5, has been constructed. By comparing the phenotypes conferred by plasmids bearing the various mutations to the phenotype of the wild type upon transformation of strains NM81 (delta nhaA) or EP432 (delta nhaA, delta nhaB) we found that none of the NhaA histidines are essential for the Na+/H+ antiporter activity of the NhaA protein. However, the replacement of His-226 by Arg markedly changes the pH dependence of the antiporter. All mutants except H226R confer to NM81 and EP432 Na+ resistance up to pH 8.5 as well as Li+ resistance. Cells bearing H226R are resistant to Li+ and to Na+ at neutral pH, but they become sensitive to Na+ above pH 7.5. Analysis of the Na+/H+ antiporter activity of membrane vesicles derived from H226R cells shows that the mutated protein is activated by pH to the same extent as the wild type. However, whereas the activation of the wild-type NhaA occurs between pH 7 and pH 8, that of H226R antiporter occurs between pH 6.5 and pH 7.5. Furthermore, while the wild-type antiporter remains almost fully active at least up to pH 8.5, H226R is reversibly inactivated above pH 7.5, reaching 10-20% of the maximal activity at pH 8.5. We suggest that His-226 is part of a pH-sensitive site that regulates the activity of NhaA.
Full text
PDFImages in this article
Selected References
These references are in PubMed. This may not be the complete list of references from this article.
- Ambudkar S. V., Zlotnick G. W., Rosen B. P. Calcium efflux from Escherichia coli. Evidence for two systems. J Biol Chem. 1984 May 25;259(10):6142–6146. [PubMed] [Google Scholar]
- Aronson P. S. Kinetic properties of the plasma membrane Na+-H+ exchanger. Annu Rev Physiol. 1985;47:545–560. doi: 10.1146/annurev.ph.47.030185.002553. [DOI] [PubMed] [Google Scholar]
- Bradford M. M. A rapid and sensitive method for the quantitation of microgram quantities of protein utilizing the principle of protein-dye binding. Anal Biochem. 1976 May 7;72:248–254. doi: 10.1016/0003-2697(76)90527-3. [DOI] [PubMed] [Google Scholar]
- Brey R. N., Beck J. C., Rosen B. P. Cation/proton antiport systems in Escherichia coli. Biochem Biophys Res Commun. 1978 Aug 29;83(4):1588–1594. doi: 10.1016/0006-291x(78)91403-1. [DOI] [PubMed] [Google Scholar]
- DAVIS B. D., MINGIOLI E. S. Mutants of Escherichia coli requiring methionine or vitamin B12. J Bacteriol. 1950 Jul;60(1):17–28. doi: 10.1128/jb.60.1.17-28.1950. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Damiano E., Bassilana M., Leblanc G. Chemical modifications of the Na+-H+ antiport in Escherichia coli membrane vesicles. Eur J Biochem. 1985 Apr 1;148(1):183–188. doi: 10.1111/j.1432-1033.1985.tb08823.x. [DOI] [PubMed] [Google Scholar]
- Goldberg E. B., Arbel T., Chen J., Karpel R., Mackie G. A., Schuldiner S., Padan E. Characterization of a Na+/H+ antiporter gene of Escherichia coli. Proc Natl Acad Sci U S A. 1987 May;84(9):2615–2619. doi: 10.1073/pnas.84.9.2615. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Ho S. N., Hunt H. D., Horton R. M., Pullen J. K., Pease L. R. Site-directed mutagenesis by overlap extension using the polymerase chain reaction. Gene. 1989 Apr 15;77(1):51–59. doi: 10.1016/0378-1119(89)90358-2. [DOI] [PubMed] [Google Scholar]
- Kaback H. R. Site-directed mutagenesis and ion-gradient driven active transport: on the path of the proton. Annu Rev Physiol. 1988;50:243–256. doi: 10.1146/annurev.ph.50.030188.001331. [DOI] [PubMed] [Google Scholar]
- Karpel R., Alon T., Glaser G., Schuldiner S., Padan E. Expression of a sodium proton antiporter (NhaA) in Escherichia coli is induced by Na+ and Li+ ions. J Biol Chem. 1991 Nov 15;266(32):21753–21759. [PubMed] [Google Scholar]
- Karpel R., Olami Y., Taglicht D., Schuldiner S., Padan E. Sequencing of the gene ant which affects the Na+/H+ antiporter activity in Escherichia coli. J Biol Chem. 1988 Jul 25;263(21):10408–10414. [PubMed] [Google Scholar]
- King S. M., Otter T., Witman G. B. Characterization of monoclonal antibodies against Chlamydomonas flagellar dyneins by high-resolution protein blotting. Proc Natl Acad Sci U S A. 1985 Jul;82(14):4717–4721. doi: 10.1073/pnas.82.14.4717. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 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]
- Olsnes S., Tønnessen T. I., Ludt J., Sandvig K. Effect of intracellular pH on the rate of chloride uptake and efflux in different mammalian cell lines. Biochemistry. 1987 May 19;26(10):2778–2785. doi: 10.1021/bi00384a019. [DOI] [PubMed] [Google Scholar]
- Padan E., Maisler N., Taglicht D., Karpel R., Schuldiner S. Deletion of ant in Escherichia coli reveals its function in adaptation to high salinity and an alternative Na+/H+ antiporter system(s). J Biol Chem. 1989 Dec 5;264(34):20297–20302. [PubMed] [Google Scholar]
- Padan E., Sarkar H. K., Viitanen P. V., Poonian M. S., Kaback H. R. Site-specific mutagenesis of histidine residues in the lac permease of Escherichia coli. Proc Natl Acad Sci U S A. 1985 Oct;82(20):6765–6768. doi: 10.1073/pnas.82.20.6765. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Padan E., Zilberstein D., Rottenberg H. The proton electrochemical gradient in Escherichia coli cells. Eur J Biochem. 1976 Apr 1;63(2):533–541. doi: 10.1111/j.1432-1033.1976.tb10257.x. [DOI] [PubMed] [Google Scholar]
- Pinner E., Padan E., Schuldiner S. Cloning, sequencing, and expression of the nhaB gene, encoding a Na+/H+ antiporter in Escherichia coli. J Biol Chem. 1992 Jun 5;267(16):11064–11068. [PubMed] [Google Scholar]
- Rahav-Manor O., Carmel O., Karpel R., Taglicht D., Glaser G., Schuldiner S., Padan E. NhaR, a protein homologous to a family of bacterial regulatory proteins (LysR), regulates nhaA, the sodium proton antiporter gene in Escherichia coli. J Biol Chem. 1992 May 25;267(15):10433–10438. [PubMed] [Google Scholar]
- Rosen B. P. Ion extrusion systems in Escherichia coli. Methods Enzymol. 1986;125:328–336. doi: 10.1016/s0076-6879(86)25028-4. [DOI] [PubMed] [Google Scholar]
- Sardet C., Counillon L., Franchi A., Pouysségur J. Growth factors induce phosphorylation of the Na+/H+ antiporter, glycoprotein of 110 kD. Science. 1990 Feb 9;247(4943):723–726. doi: 10.1126/science.2154036. [DOI] [PubMed] [Google Scholar]
- Schuldiner S., Fishkes H. Sodium-proton antiport in isolated membrane vesicles of Escherichia coli. Biochemistry. 1978 Feb 21;17(4):706–711. doi: 10.1021/bi00597a023. [DOI] [PubMed] [Google Scholar]
- Schägger H., von Jagow G. Tricine-sodium dodecyl sulfate-polyacrylamide gel electrophoresis for the separation of proteins in the range from 1 to 100 kDa. Anal Biochem. 1987 Nov 1;166(2):368–379. doi: 10.1016/0003-2697(87)90587-2. [DOI] [PubMed] [Google Scholar]
- Tabor S., Richardson C. C. A bacteriophage T7 RNA polymerase/promoter system for controlled exclusive expression of specific genes. Proc Natl Acad Sci U S A. 1985 Feb;82(4):1074–1078. doi: 10.1073/pnas.82.4.1074. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Taglicht D., Padan E., Schuldiner S. Overproduction and purification of a functional Na+/H+ antiporter coded by nhaA (ant) from Escherichia coli. J Biol Chem. 1991 Jun 15;266(17):11289–11294. [PubMed] [Google Scholar]