Abstract
Gibberellin (GA) is one of the important plant hormone involving plant growth and development. GA response is controlled by a nuclear repressor DELLA protein. Once plant cells receive GA molecules, DELLA proteins are rapidly degraded by ubiquitin-proteasome pathway. GA perception and following DELLA protein recognition by GA receptor GID1 cause ubiquitination and destruction of DELLA proteins triggering the GA response. However, there are few studies of structural analysis of GA signaling components. Here, we determined crystal structures of Arabidopsis GID1 in complex with GA and DELLA N-terminal domain at 1.8 angstrom resolution. GA molecule is binding with a pocket of GID1 core domain and sealed by the GID1 N-terminal extension. DELLA and VHYNP motifs of DELLA protein mainly interact with N-terminal extension of GID1. These results suggest that GA molecule induces conformational change of GID1 N-terminal extension and formation of scaffold for DELLA protein recognition.
