Thefou2mutation in the major vacuolar cation channel TPC1 confers tolerance to inhibitory luminal calcium
| Autor: | Jörg Fromm, Enrico Martinoia, Irene Marten, Diana Beyhl, Edward E. Farmer, Stefan Hörtensteiner, Rainer Hedrich |
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| Rok vydání: | 2009 |
| Předmět: |
Patch-Clamp Techniques
Mutant Arabidopsis chemistry.chemical_element Plant Science Vacuole Biology Calcium Membrane Potentials Cytosol Downregulation and upregulation Gene Expression Regulation Plant Genetics Point Mutation Arabidopsis thaliana Calcium Signaling Jasmonate Patch clamp Arabidopsis Proteins Cell Biology biology.organism_classification Cell biology Biochemistry chemistry Vacuoles Potassium Calcium Channels Homeostasis |
| Zdroj: | The Plant Journal. 58:715-723 |
| ISSN: | 1365-313X 0960-7412 |
| DOI: | 10.1111/j.1365-313x.2009.03820.x |
| Popis: | Summary The SV channel encoded by the TPC1 gene represents a Ca(2+)- and voltage-dependent vacuolar cation channel. Point mutation D454N within TPC1, named fou2 for fatty acid oxygenation upregulated 2, results in increased synthesis of the stress hormone jasmonate. As wounding causes Ca(2+) signals and cytosolic Ca(2+) is required for SV channel function, we here studied the Ca(2+)-dependent properties of this major vacuolar cation channel with Arabidopsis thaliana mesophyll vacuoles. In patch clamp measurements, wild-type and fou2 SV channels did not exhibit differences in cytosolic Ca(2+) sensitivity and Ca(2+) impermeability. K(+) fluxes through wild-type TPC1 were reduced or even completely faded away when vacuolar Ca(2+) reached the 0.1-mm level. The fou2 protein under these conditions, however, remained active. Thus, D454N seems to be part of a luminal Ca(2+) recognition site. Thereby the SV channel mutant gains tolerance towards elevated luminal Ca(2+). A three-fold higher vacuolar Ca/K ratio in the fou2 mutant relative to wild-type plants seems to indicate that fou2 can accumulate higher levels of vacuolar Ca(2+) before SV channel activity vanishes and K(+) homeostasis is impaired. In response to wounding fou2 plants might thus elicit strong vacuole-derived cytosolic Ca(2+) signals resulting in overproduction of jasmonate. |
| Databáze: | OpenAIRE |
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