Arabidopsis Annexin1 Mediates the Radical-Activated Plasma Membrane Ca²⁺- and K⁺-Permeable Conductance in Root Cells

Plant cell growth and stress signaling require Ca²⁺ influx through plasma membrane transport proteins that are regulated by reactive oxygen species. In root cell growth, adaptation to salinity stress, and stomatal closure, such proteins operate downstream of the plasma membrane NADPH oxidases that p...

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Published in:	The Plant cell 2012-04, Vol.24 (4), p.1522-1533
Main Authors:	Laohavisit, Anuphon, Shang, Zhonglin, Rubio, Lourdes, Cuin, Tracey A., Véry, Anne-Aliénor, Wang, Aihua, Mortimer, Jennifer C., Macpherson, Neil, Coxon, Katy M., Battey, Nicholas H., Brownlee, Colin, Park, Ohkmae K., Sentenac, Hervé, Shabala, Sergey, Webb, Alex A.R., Davies, Julia M.
Format:	Article
Language:	eng
Subjects:	Annexin A1 Annexin A1 - metabolism Annexins Arabidopsis Arabidopsis - cytology Arabidopsis - drug effects Arabidopsis - physiology Arabidopsis Proteins Arabidopsis Proteins - metabolism Calcium Calcium - metabolism Calcium Channels Calcium Channels - metabolism Cell growth Cell Membrane Cell Membrane - drug effects Cell Membrane - metabolism Cell Membrane Permeability Cell Membrane Permeability - drug effects Cell membranes Diffusion Diffusion - drug effects Electric potential Epidermis Hydroxyl Radical Hydroxyl Radical - pharmacology Ion Channel Gating Ion Channel Gating - drug effects Life Sciences Lipid Bilayers Lipid Bilayers - metabolism Plant Cells Plant Cells - drug effects Plant Cells - metabolism Plant Epidermis Plant Epidermis - drug effects Plant Epidermis - metabolism Plant Roots Plant Roots - cytology Plant Roots - drug effects Plant Roots - physiology Plants Potassium Potassium - metabolism Protoplasts Protoplasts - drug effects Protoplasts - metabolism Recombinant Proteins Recombinant Proteins - isolation & purification Root hairs Shaker Superfamily of Potassium Channels Shaker Superfamily of Potassium Channels - metabolism Vegetal Biology
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Summary:	Plant cell growth and stress signaling require Ca²⁺ influx through plasma membrane transport proteins that are regulated by reactive oxygen species. In root cell growth, adaptation to salinity stress, and stomatal closure, such proteins operate downstream of the plasma membrane NADPH oxidases that produce extracellular Superoxide anion, a reactive oxygen species that is readily converted to extracellular hydrogen peroxide and hydroxyl radicals, OH˙ In root cells, extracellular OH˙ activates a plasma membrane Ca²⁺ -permeable conductance that permits Ca²⁺ influx. In Arabidopsis thaliana, distribution of this conductance resembles that of annexin1 (ANN1). Annexins are membrane binding proteins that can form Ca²⁺ -permeable conductances in vitro. Here, the Arabidopsis loss-of-function mutant for annexin1 (Atann1) was found to lack the root hair and epidermal OH˙-activated Ca²⁺ -and K⁺ -permeable conductance. This manifests in both impaired root cell growth and ability to elevate root cell cytosolic free Ca²⁺ in response to OH˙. An OH˙-activated Ca²⁺ conductance is reconstituted by recombinant ANN1 in planar lipid bilayers. ANN1 therefore presents as a novel Ca²⁺-permeable transporter providing a molecular link between reactive oxygen species and cytosolic Ca²⁺ in plants.
ISSN:	1040-4651 1532-298X