CDPKs (calcium-dependent protein kinases), which contain both calmodulin-like calcium binding and serine/threonine protein kinase domains, are only present in plants and some protozoans. Upon activation by a stimulus, they transduce the signal through phosphorylation cascades to induce downstream responses, including transcriptional regulation. To understand the functional specificities of CDPKs, 14 Arabidopsis CPKs (CDPKs in plants) representative of the three main subgroups were characterized at the biochemical level, using HA (haemagglutinin)-tagged CPKs expressed in planta. Most of them were partially or mainly associated with membranes, in agreement with acylation predictions. Importantly, CPKs displayed highly variable calcium-dependences for their kinase activities: seven CPKs from subgroups 1 and 2 were clearly sensitive to calcium with different intensities, whereas six CPKs from subgroup 3 exhibited low or no calcium sensitivity to two generic substrates. Interestingly, this apparent calcium-independence correlated with significant alterations in the predicted EF-hands of these kinases, although they all bound calcium. The noticeable exception, CPK25, was calcium-independent owing to the absence of functional EF-hands. Taken together, the results of the present study suggest that calcium binding differentially affects CDPK isoforms that may be activated by distinct molecular mechanisms.
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Research Article|
September 26 2012
Characterization of Arabidopsis calcium-dependent protein kinases: activated or not by calcium?
Marie Boudsocq;
*Institut des Sciences du Végétal, UPR 2355, CNRS, 1 av. de la terrasse, 91198 Gif s/Yvette cedex, France
2To whom correspondence should be addressed (email boudsocq@evry.inra.fr).
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Marie-Jo Droillard;
Marie-Jo Droillard
*Institut des Sciences du Végétal, UPR 2355, CNRS, 1 av. de la terrasse, 91198 Gif s/Yvette cedex, France
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Leslie Regad;
Leslie Regad
†MTi, Université Paris Diderot, Sorbonne Paris Cité, INSERM U973, 75013 Paris, France
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Christiane Laurière
Christiane Laurière
*Institut des Sciences du Végétal, UPR 2355, CNRS, 1 av. de la terrasse, 91198 Gif s/Yvette cedex, France
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Publisher: Portland Press Ltd
Received:
November 23 2011
Revision Received:
June 27 2012
Accepted:
July 24 2012
Accepted Manuscript online:
July 24 2012
Online ISSN: 1470-8728
Print ISSN: 0264-6021
© The Authors Journal compilation © 2012 Biochemical Society
2012
Biochem J (2012) 447 (2): 291–299.
Article history
Received:
November 23 2011
Revision Received:
June 27 2012
Accepted:
July 24 2012
Accepted Manuscript online:
July 24 2012
Citation
Marie Boudsocq, Marie-Jo Droillard, Leslie Regad, Christiane Laurière; Characterization of Arabidopsis calcium-dependent protein kinases: activated or not by calcium?. Biochem J 15 October 2012; 447 (2): 291–299. doi: https://doi.org/10.1042/BJ20112072
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