The plasma membrane of the California poppy is known to harbour a PLA2 (phospholipase A2) that is associated with the Gα protein which facilitates its activation by a yeast glycoprotein, thereby eliciting the biosynthesis of phytoalexins. To understand the functional architecture of the protein complex, we titrated purified plasma membranes with the Gα protein (native or recombinant) and found that critical amounts of this subunit keep PLA2 in a low-activity state from which it is released either by elicitor plus GTP or by raising the Gα concentration, which probably causes oligomerization of Gα, as supported by FRET (fluorescence resonance energy transfer)-orientated fluorescence imaging and a semiquantitative split-ubiquitin assay. All effects of Gα were blocked by specific antibodies. A low-Gα mutant showed elevated PLA2 activity and lacked the GTP-dependent stimulation by elicitor, but regained this capability after pre-incubation with Gα. The inhibition by Gα and the GTP-dependent stimulation of PLA2 were diminished by inhibitors of peptidylprolyl cis–trans isomerases. A cyclophilin was identified by sequence in the plasma membrane and in immunoprecipitates with anti-Gα antibodies. We conclude that soluble and target-associated Gα interact at the plasma membrane to build complexes of varying architecture and signal amplification. Protein-folding activity is probably required to convey conformational transitions from Gα to its target PLA2.
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Research Article|
February 28 2013
Signal transfer in the plant plasma membrane: phospholipase A2 is regulated via an inhibitory Gα protein and a cyclophilin
Michael Heinze;
Michael Heinze
*Martin-Luther-University Halle-Wittenberg, Institute of Pharmacy, Department of Molecular Cell Biology, Kurt-Mothes-Str. 3, 06120 Halle, Germany
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Madeleine Herre;
Madeleine Herre
*Martin-Luther-University Halle-Wittenberg, Institute of Pharmacy, Department of Molecular Cell Biology, Kurt-Mothes-Str. 3, 06120 Halle, Germany
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Carolin Massalski;
Carolin Massalski
*Martin-Luther-University Halle-Wittenberg, Institute of Pharmacy, Department of Molecular Cell Biology, Kurt-Mothes-Str. 3, 06120 Halle, Germany
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Isabella Hermann;
Isabella Hermann
†Leibniz-Institute of Plant Genetics and Crop Plant Research Corrensstrasse 3, D-06466 Gatersleben, Germany
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Udo Conrad;
Udo Conrad
†Leibniz-Institute of Plant Genetics and Crop Plant Research Corrensstrasse 3, D-06466 Gatersleben, Germany
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Werner Roos
Werner Roos
1
*Martin-Luther-University Halle-Wittenberg, Institute of Pharmacy, Department of Molecular Cell Biology, Kurt-Mothes-Str. 3, 06120 Halle, Germany
1To whom correspondence should be addressed (email werner.roos@pharmazie.uni-halle.de).
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Publisher: Portland Press Ltd
Received:
May 11 2012
Revision Received:
December 12 2012
Accepted:
December 19 2012
Accepted Manuscript online:
December 19 2012
Online ISSN: 1470-8728
Print ISSN: 0264-6021
© The Authors Journal compilation © 2013 Biochemical Society
2013
Biochem J (2013) 450 (3): 497–509.
Article history
Received:
May 11 2012
Revision Received:
December 12 2012
Accepted:
December 19 2012
Accepted Manuscript online:
December 19 2012
Citation
Michael Heinze, Madeleine Herre, Carolin Massalski, Isabella Hermann, Udo Conrad, Werner Roos; Signal transfer in the plant plasma membrane: phospholipase A2 is regulated via an inhibitory Gα protein and a cyclophilin. Biochem J 15 March 2013; 450 (3): 497–509. doi: https://doi.org/10.1042/BJ20120793
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