Permanent URL to this publication: http://dx.doi.org/10.5167/uzh-53840
Meyer, S; Scholz-Starke, J; De Angeli, A; Kovermann, P; Burla, B; Gambale, F; Martinoia, E (2011). Malate transport by the vacuolar AtALMT6 channel in guard cells is subject to multiple regulation. The Plant Journal, 67(2):247-257.
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Gas exchange in plants is controlled by guard cells, specialized cells acting as turgor pressure-driven valves. Malate is one of the major anions accumulated inside the vacuole during stomatal opening counteracting the positive charge of potassium. AtALMT6, a member of the aluminum-activated malate transporter family, is expressed in guard cells of leaves and stems as well as in flower organs of Arabidopsis thaliana. An AtALMT6-GFP fusion protein was targeted to the vacuolar membrane both in transient and stable expression systems. Patch-clamp experiments on vacuoles isolated from AtALMT6-GFP over-expressing Arabidopsis plants revealed large inward-rectifying malate currents only in the presence of micromolar cytosolic calcium concentrations. Further analyses showed that vacuolar pH and cytosolic malate regulate the threshold of activation of AtALMT6-mediated currents. The interplay of these two factors determines the AtALMT6 function as a malate influx or efflux channel depending on the tonoplast potential. Guard cell vacuoles isolated from Atalmt6 knock-out plants displayed reduced malate currents compared with wild-type vacuoles. This reduction, however, was not accompanied by phenotypic differences in the stomatal movements in knock-out plants, probably because of functional redundancy of malate transporters in guard cell vacuoles.
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|Item Type:||Journal Article, refereed, original work|
|Communities & Collections:||07 Faculty of Science > Institute of Plant Biology|
|Dewey Decimal Classification:||580 Plants (Botany)|
|Deposited On:||03 Jan 2012 18:02|
|Last Modified:||31 Dec 2013 00:49|
|Additional Information:||The definitive version is available at www.blackwell-synergy.com|
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