Abstract
It has been proposed that the binding of GA to GID1 induces interaction between GID1 and DELLA protein, a repressor of GA signaling, and resulting in the degradation of DELLA protein. We isolated and focused one suppressor mutant of gid1, Sgd-1. Sgd-1 carried one amino acid substitution (P99S) in the OsGID1 locus, which causes an interaction between GID1 and DELLA in the absence of GA. We found another mutant GID1 with P99A that has the highest GA-independent DELLA interacting activity. Through the analyses of OsGID1P99A or P99S by Y2H assay and Surface Plasmon Resonance, we revealed that these mutated GID1s have a close state of the lid without GA resulting in DELLA interaction.
It has been reported that AtGID1b also interacts with DELLA in GA independent manner. Mutation analysis revealed that such GA-independency depends on a similar mechanism of the OsGID1P99A-DELLA interaction. We also found that some dicot GID1s have similar GA independent GID1-DELLA interacting activity.
A part of this research is supported by target protein, KAKENHI (18107001), and new agricultural project (IPG0003).
