Abstract
Proton pumps of tonoplast membranes have been studied extensively in vitro, but data concerning their regulation in vivo are lacking. Effects of either anoxia, or the addition of KCN, 2-deoxy-d-glucose (deoxy-glucose), or bafilomycin-A1 (BAF) on vacuolar pH of maize (Zea mays L.) root hair cells were followed by fluorescence microscopy after loading of 2[prime]7[prime]-bis-(2-carboxyethyl)-5-(and-6) carboxyfluorescein. Root hair cells were able to maintain vacuolar acidity for at least 2 h in the presence of either 10 mM KCN or 50 mM deoxy-glucose or during anoxia. Treatments with either deoxy-glucose or KCN reduced total tissue ATP more than anoxia. ADP accumulated during anoxia and treatment with KCN as detected by in vivo 31P-NMR spectroscopy, but not during deoxy-glucose treatment. With control roots and roots treated with deoxy-glucose, the presence of BAF, a specific inhibitor of the V-type ATPase, caused alkalization of the vacuolar pH. However, either in the presence of KCN or under anoxic conditions, BAF was relatively ineffective in dissipating vacuolar acidity. Therefore, under anoxia or in the presence of KCN, unlike the situation with air or deoxy-glucose, the V-type ATPase apparently is not required for maintenance of vacuolar acidity.
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- Bensadoun A., Weinstein D. Assay of proteins in the presence of interfering materials. Anal Biochem. 1976 Jan;70(1):241–250. doi: 10.1016/s0003-2697(76)80064-4. [DOI] [PubMed] [Google Scholar]
- Bowman E. J., Siebers A., Altendorf K. Bafilomycins: a class of inhibitors of membrane ATPases from microorganisms, animal cells, and plant cells. Proc Natl Acad Sci U S A. 1988 Nov;85(21):7972–7976. doi: 10.1073/pnas.85.21.7972. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Crider B. P., Xie X. S., Stone D. K. Bafilomycin inhibits proton flow through the H+ channel of vacuolar proton pumps. J Biol Chem. 1994 Jul 1;269(26):17379–17381. [PubMed] [Google Scholar]
- Gogarten J. P., Fichmann J., Braun Y., Morgan L., Styles P., Taiz S. L., DeLapp K., Taiz L. The use of antisense mRNA to inhibit the tonoplast H+ ATPase in carrot. Plant Cell. 1992 Jul;4(7):851–864. doi: 10.1105/tpc.4.7.851. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Hooks M. A., Clark R. A., Nieman R. H., Roberts J. K. Compartmentation of Nucleotides in Corn Root Tips Studied by P-NMR and HPLC. Plant Physiol. 1989 Mar;89(3):963–969. doi: 10.1104/pp.89.3.963. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Hooks M. A., Shearer G. C., Roberts JKM. Nucleotide Availability in Maize (Zea mays L.) Root Tips (Estimation of Free and Protein-Bound Nucleotides Using 31P-Nuclear Magnetic Resonance and a Novel Protein-Ligand-Binding Assay). Plant Physiol. 1994 Feb;104(2):581–589. doi: 10.1104/pp.104.2.581. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Maeshima M. H(+)-translocating inorganic pyrophosphatase of plant vacuoles. Inhibition by Ca2+, stabilization by Mg2+ and immunological comparison with other inorganic pyrophosphatases. Eur J Biochem. 1991 Feb 26;196(1):11–17. doi: 10.1111/j.1432-1033.1991.tb15779.x. [DOI] [PubMed] [Google Scholar]
- Nelson N., Taiz L. The evolution of H+-ATPases. Trends Biochem Sci. 1989 Mar;14(3):113–116. doi: 10.1016/0968-0004(89)90134-5. [DOI] [PubMed] [Google Scholar]
- Roberts J. K., Lane A. N., Clark R. A., Nieman R. H. Relationships between the rate of synthesis of ATP and the concentrations of reactants and products of ATP hydrolysis in maize root tips, determined by 31P nuclear magnetic resonance. Arch Biochem Biophys. 1985 Aug 1;240(2):712–722. doi: 10.1016/0003-9861(85)90080-3. [DOI] [PubMed] [Google Scholar]
- Tu S. I., Brouillette J. N., Nagahashi G., Brauer D., Nungesser E. Temperature dependence and mercury inhibition of tonoplast-type H+-ATPase. Arch Biochem Biophys. 1988 Oct;266(1):289–297. doi: 10.1016/0003-9861(88)90261-5. [DOI] [PubMed] [Google Scholar]
- White P. J., Marshall J., Smith J. A. Substrate kinetics of the tonoplast h-translocating inorganic pyrophosphatase and its activation by free mg. Plant Physiol. 1990 Jul;93(3):1063–1070. doi: 10.1104/pp.93.3.1063. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Yoshimori T., Yamamoto A., Moriyama Y., Futai M., Tashiro Y. Bafilomycin A1, a specific inhibitor of vacuolar-type H(+)-ATPase, inhibits acidification and protein degradation in lysosomes of cultured cells. J Biol Chem. 1991 Sep 15;266(26):17707–17712. [PubMed] [Google Scholar]