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

• 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: English
• 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
• ISSN: 1040-4651; 1532-298X
• DOI: 10.1105/tpc.112.097881

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.