title: Analysis of MADS box protein-protein interactions in living plant cells.
abstract: Over the last decade, the yeast two-hybrid system has become the tool to use for the identification of protein-protein interactions and recently, even complete interactomes were elucidated by this method. Nevertheless, it is an artificial system that is sensitive to errors resulting in the identification of false-positive and false-negative interactions. In this study, plant MADS box transcription factor interactions identified by yeast two-hybrid systems where studied in living plant cells by a technique based on fluorescence resonance energy transfer (FRET). Petunia MADS box proteins were fused to either cyan fluorescent protein or yellow fluorescent protein and transiently expressed in protoplasts followed by FRET-spectral imaging microscopy and FRET-fluorescence lifetime imaging microscopy to detect FRET and hence protein-protein interactions. All petunia MADS box heterodimers identified in yeast were confirmed in protoplasts. However, in contrast to the yeast two-hybrid results, homodimerization was demonstrated in plant cells for three petunia MADS box proteins. Heterodimers were identified between the ovule-specific MADS box protein FLORAL BINDING PROTEIN 11 and members of the petunia FLORAL BINDING PROTEIN 2 subfamily, which are also expressed in ovules, suggesting that these dimers play a role in ovule development. Furthermore, the role of dimerization in translocation of MADS box protein dimers to the nucleus is demonstrated, and the nuclear localization signal of MADS box proteins has been mapped to the N-terminal region of the MADS domain by means of mutant analyses.
authors.affiliation: Plant Research International, P.O. Box 16, 6700 AA Wageningen, The Netherlands.
authors.forename: Richard G H
authors.initials: RG
authors.lastname: Immink
authors.forename: Theodorus W J
authors.initials: TW
authors.lastname: Gadella
authors.forename: Silvia
authors.initials: S
authors.lastname: Ferrario
authors.forename: Marco
authors.initials: M
authors.lastname: Busscher
authors.forename: Gerco C
authors.initials: GC
authors.lastname: Angenent
mesh_terms: D021581:Active Transport, Cell Nucleus; D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000737:chemistry; D019281:Dimerization; D017403:In Situ Hybridization; D008164:Luminescent Proteins / Q000737:chemistry; D026161:MADS Domain Proteins / Q000737:chemistry* / Q000235:genetics*; D008969:Molecular Sequence Data; D010802:Phylogeny; D010940:Plant Proteins / Q000737:chemistry* / Q000235:genetics*; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D011993:Recombinant Fusion Proteins / Q000737:chemistry; D017550:Spectroscopy, Fourier Transform Infrared; D014157:Transcription Factors / Q000737:chemistry / Q000235:genetics; D014162:Transfection; D020798:Two-Hybrid System Techniques
chemical_list: D001426:Bacterial Proteins; C419020:FBP9 protein, Petunia hybrida; D008164:Luminescent Proteins; D026161:MADS Domain Proteins; D010940:Plant Proteins; D011993:Recombinant Fusion Proteins; D014157:Transcription Factors; C054562:yellow fluorescent protein, Bacteria