Sriskanthadevan S, Brar SK, Manoharan K, Siu CH. Ca(2+) -calmodulin interacts with DdCAD-1 and promotes DdCAD-1 transport by contractile vacuoles in Dictyostelium cells.
FEBS J 2013;
280:1795-806. [PMID:
23441816 DOI:
10.1111/febs.12203]
[Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2012] [Revised: 01/18/2013] [Accepted: 01/25/2013] [Indexed: 11/28/2022]
Abstract
UNLABELLED
The Ca(2+) -dependent cell-cell adhesion molecule DdCAD-1, encoded by the cadA gene of Dictyostelium discoideum, is synthesized at the onset of development as a soluble protein and then transported to the plasma membrane by contractile vacuoles. Calmodulin associates with contractile vacuoles in a Ca(2+) -dependent manner, and co-localizes with DdCAD-1 on the surface of contractile vacuoles. Bioinformatics analysis revealed multiple calmodulin-binding motifs in DdCAD-1. Co-immunoprecipitation and pull-down studies showed that only Ca(2+) -bound calmodulin was able to bind DdCAD-1. Structural integrity of DdCAD-1, but not the native conformation, was required for its interaction with calmodulin. To investigate the role of calmodulin in the import of DdCAD-1 into contractile vacuoles, an in vitro import assay consisting of contractile vacuoles derived from cadA(-) cells and recombinant proteins was employed. Prior stripping of the bound calmodulin from contractile vacuoles by EGTA impaired import of DdCAD-1, which was restored by addition of exogenous calmodulin. The calmodulin antagonists W-7 and compound 48/80 blocked the binding of calmodulin onto stripped contractile vacuoles, and inhibited the import of DdCAD-1. Together, the data show that calmodulin forms a complex with DdCAD-1 and promotes the docking and import of DdCAD-1 into contractile vacuoles.
STRUCTURED DIGITAL ABSTRACT
CaM physically interacts with DdCAD-1 by pull down (View Interaction: 1, 2) DdCAD-1 binds to CaM by far western blotting (View interaction) DdCAD-1 physically interacts with CaM by anti bait coimmunoprecipitation (View interaction).
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