title: Homodimerization of Ehd1 Is Required to Induce Flowering in Rice.
abstract: In plants, flowering time is elaborately controlled by various environment factors. Ultimately, florigens such as FLOWERING LOCUS T (FT) or FT-like molecules induce flowering. In rice (Oryza sativa), Early heading date 1 (Ehd1) is a major inducer of florigen gene expression. Although Ehd1 is highly homologous to the type-B response regulator (RR) family in the cytokinin signaling pathway, its precise molecular mechanism is not well understood. In this study, we showed that the C-terminal portion of the protein containing the GARP DNA-binding (G) domain can promote flowering when overexpressed. We also observed that the N-terminal portion of Ehd1, carrying the receiver (R) domain, delays flowering by inhibiting endogenous Ehd1 activity. Ehd1 protein forms a homomer via a 16-amino acid region in the inter domain between R and G. From the site-directed mutagenesis analyses, we demonstrated that phosphorylation of the Asp-63 residue within the R domain induces the homomerization of Ehd1, which is crucial for Ehd1 activity. A type-A RR, OsRR1, physically interacts with Ehd1 to form a heterodimer. In addition, OsRR1-overexpressing plants show a late-flowering phenotype. Based on these observations, we conclude that OsRR1 inhibits Ehd1 activity by binding to form an inactive complex.
authors: Crop Biotech Institute, Kyung Hee University, Yongin 446-701, Korea (L.-H.C., J.Y., R.P., G.A.);Department of Life Science, Pohang University of Science and Technology, Pohang 790-784, Korea (L.-H.C., J.Y.); andGraduate School of Biotechnology, Kyung Hee University, Yongin 446-701, Korea (R.P., G.A.).
authors: Lae-Hyeon
authors: LH
authors: Cho
authors: Crop Biotech Institute, Kyung Hee University, Yongin 446-701, Korea (L.-H.C., J.Y., R.P., G.A.);Department of Life Science, Pohang University of Science and Technology, Pohang 790-784, Korea (L.-H.C., J.Y.); andGraduate School of Biotechnology, Kyung Hee University, Yongin 446-701, Korea (R.P., G.A.).
authors: Jinmi
authors: J
authors: Yoon
authors: Crop Biotech Institute, Kyung Hee University, Yongin 446-701, Korea (L.-H.C., J.Y., R.P., G.A.);Department of Life Science, Pohang University of Science and Technology, Pohang 790-784, Korea (L.-H.C., J.Y.); andGraduate School of Biotechnology, Kyung Hee University, Yongin 446-701, Korea (R.P., G.A.).
authors: Richa
authors: R
authors: Pasriga
authors: Crop Biotech Institute, Kyung Hee University, Yongin 446-701, Korea (L.-H.C., J.Y., R.P., G.A.);Department of Life Science, Pohang University of Science and Technology, Pohang 790-784, Korea (L.-H.C., J.Y.); andGraduate School of Biotechnology, Kyung Hee University, Yongin 446-701, Korea (R.P., G.A.) genean@khu.ac.kr.
authors: Gynheung
authors: G
authors: An
mesh_terms: D001224:Aspartic Acid / Q000378:metabolism; D035264:Flowers / Q000235:genetics / Q000502:physiology*; D008954:Models, Biological; D050505:Mutant Proteins / Q000378:metabolism; D019913:Nuclear Localization Signals / Q000378:metabolism; D012275:Oryza / Q000235:genetics / Q000502:physiology*; D010641:Phenotype; D010766:Phosphorylation; D010940:Plant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D030821:Plants, Genetically Modified; D011485:Protein Binding; D000072417:Protein Domains; D055503:Protein Multimerization; D014158:Transcription, Genetic; D015533:Transcriptional Activation / Q000235:genetics; D020798:Two-Hybrid System Techniques
chemical_list: D050505:Mutant Proteins; D019913:Nuclear Localization Signals; D010940:Plant Proteins; D001224:Aspartic Acid