Zea mays annexins modulate cytosolic free Ca2+ and generate a Ca2+-permeable conductance

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Title Zea mays annexins modulate cytosolic free Ca2+ and generate a Ca2+-permeable conductance
Author Laohavisit, Anuphon; Mortimer, Jennifer C.; Demidchik, Vadim; Coxon, Laty M.; Stancombe, Matthew A.; Macpherson, Neil; Brownlee, Colin; Hofmann, Andreas; Webb, Alex A.R.; Miedema, Henk; Battey, Nicholas H.; Davies, Julia M.
Journal Name Plant Cell
Year Published 2009
Place of publication United States
Publisher American Society of Plant Biologists
Abstract Regulation of reactive oxygen species and cytosolic free calcium ([Ca2+]cyt) is central to plant function. Annexins are small proteins capable of Ca2+-dependent membrane binding or membrane insertion. They possess structural motifs that could support both peroxidase activity and calcium transport. Here, a Zea mays annexin preparation caused increases in [Ca2+]cyt when added to protoplasts of Arabidopsis thaliana roots expressing aequorin. The pharmacological profile was consistent with annexin activation (at the extracellular plasma membrane face) of Arabidopsis Ca2+-permeable nonselective cation channels. Secreted annexins could therefore modulate Ca2+ influx. As maize annexins occur in the cytosol and plasma membrane, they were incorporated at the intracellular face of lipid bilayers designed to mimic the plasma membrane. Here, they generated an instantaneously activating Ca2+-permeable conductance at mildly acidic pH that was sensitive to verapamil and Gd3+ and had a Ca2+-to-K+ permeability ratio of 0.36. These results suggest that cytosolic annexins create a Ca2+ influx pathway directly, particularly during stress responses involving acidosis. A maize annexin preparation also demonstrated in vitro peroxidase activity that appeared independent of heme association. In conclusion, this study has demonstrated that plant annexins create Ca2+-permeable transport pathways, regulate [Ca2+]cyt, and may function as peroxidases in vitro.
Peer Reviewed Yes
Published Yes
Publisher URI http://www.plantcell.org/
Alternative URI http://dx.doi.org/10.1105/tpc.108.059550
Copyright Statement Copyright 2009 American Society of Plant Biologists. Self-archiving of the author-manuscript version is not yet supported by American Scientific Publishers. Please refer to the journal link for access to the definitive, published version or contact the authors for more information.
Volume 21
Page from 479
Page to 493
ISSN 1040-4651
Date Accessioned 2009-07-09
Language en_AU
Research Centre Eskitis Institute for Drug Discovery
Faculty Faculty of Science, Environment, Engineering and Technology
Subject Analytical Biochemistry
URI http://hdl.handle.net/10072/28525
Publication Type Journal Articles (Refereed Article)
Publication Type Code c1

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