title: Multicolor bimolecular fluorescence complementation reveals simultaneous formation of alternative CBL/CIPK complexes in planta.
abstract: The specificity of intracellular signaling and developmental patterning in biological systems relies on selective interactions between different proteins in specific cellular compartments. The identification of such protein-protein interactions is essential for unraveling complex signaling and regulatory networks. Recently, bimolecular fluorescence complementation (BiFC) has emerged as a powerful technique for the efficient detection of protein interactions in their native subcellular localization. Here we report significant technical advances in the methodology of plant BiFC. We describe a series of versatile BiFC vector sets that are fully compatible with previously generated vectors. The new vectors enable the generation of both C-terminal and N-terminal fusion proteins and carry optimized fluorescent protein genes that considerably improve the sensitivity of BiFC. Using these vectors, we describe a multicolor BiFC (mcBiFC) approach for the simultaneous visualization of multiple protein interactions in the same cell. Application to a protein interaction network acting in calcium-mediated signal transduction revealed the concurrent interaction of the protein kinase CIPK24 with the calcium sensors CBL1 and CBL10 at the plasma membrane and tonoplast, respectively. We have also visualized by mcBiFC the simultaneous formation of CBL1/CIPK1 and CBL9/CIPK1 protein complexes at the plasma membrane. Thus, mcBiFC provides a useful new tool for exploring complex regulatory networks in plants.
authors.affiliation: Institut für Botanik und Botanischer Garten, Universität Münster, Schlossplatz 4, 48149 Münster, Germany.
authors.forename: Rainer
authors.initials: R
authors.lastname: Waadt
authors.forename: Lena K
authors.initials: LK
authors.lastname: Schmidt
authors.forename: Marc
authors.initials: M
authors.lastname: Lohse
authors.forename: Kenji
authors.initials: K
authors.lastname: Hashimoto
authors.forename: Ralph
authors.initials: R
authors.lastname: Bock
authors.forename: Jörg
authors.initials: J
authors.lastname: Kudla
mesh_terms: D001426:Bacterial Proteins; D002135:Calcium-Binding Proteins / Q000737:chemistry; D002462:Cell Membrane / Q000737:chemistry; D005822:Genetic Vectors; D008164:Luminescent Proteins; D008856:Microscopy, Fluorescence / Q000379:methods*; D010940:Plant Proteins / Q000737:chemistry*; D010957:Plasmids; D017346:Protein Serine-Threonine Kinases / Q000737:chemistry; D015398:Signal Transduction; D014026:Nicotiana / Q000737:chemistry* / Q000235:genetics / Q000648:ultrastructure
chemical_list: D001426:Bacterial Proteins; D002135:Calcium-Binding Proteins; D008164:Luminescent Proteins; D010940:Plant Proteins; C054562:yellow fluorescent protein, Bacteria; D017346:Protein Serine-Threonine Kinases