Calmodulin is involved in the dual subcellular location of two chloroplast proteins

Abstract : Cell compartmentalization is an essential process by which eukaryotic cells separate and control biological processes. While calmodulins are well known to regulate catalytic properties of their targets, we show here their involvement in the subcellular location of two plant proteins. Both proteins exhibit a dual location, namely in the cytosol in addition to their association to plastids (where they are known to fulfil their role). One of these proteins, ceQORH, a long-chain fatty acid reductase, was analysed in more details and its calmodulin binding site identified by specific mutations. Such a mutated form is predominantly targeted to plastids at the expense of its cytosolic location. The second protein, TIC32, was also shown to be dependent on its calmodulin binding site for retention in the cytosol. Complementary approaches (bimolecular fluorescence complementation and reverse genetics) demonstrated that the calmodulin isoform CAM5 is specifically involved in the retention of ceQORH in the cytosol. This study identifies a new role for calmodulin and sheds new light on the intriguing CaM-binding properties of hundreds of plastid proteins, despite no CaM or CaM-like proteins were identified in plastids.
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Submitted on : Monday, October 7, 2019 - 5:14:47 PM
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Lucas Moyet, Daniel Salvi, Imen Bouchnak, Stéphane Miras, Laura Perrot, et al.. Calmodulin is involved in the dual subcellular location of two chloroplast proteins. Journal of Biological Chemistry, American Society for Biochemistry and Molecular Biology, 2019, 294, pp.17543-17554. ⟨10.1074/jbc.RA119.010846⟩. ⟨hal-02307624⟩



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