Functional Analyses of Gibberellin Soluble Receptor, GID1 (II)

Abstract

Recently, we isolated a GA insensitive dwarf mutant of rice, gid1. GID1 encodes a soluble GA receptor that shares sequence similarity with a hormone sensitive lipase (HSL). The GID1-GA complex directly interacts with SLR1, a DELLA repressor protein associated with GA signaling. In this study, we performed the domain analysis of GID1 protein using 94 GID1 proteins, which were independently mutated in the manner of alanine scanning. We analyzed both in vitro GA binding activity and SLR1 interacting activity of each mutated GID1 protein.
We also examined the interaction between GID1 and SLR1 protein in vivo. GID1-GFP was over-expressed in rice callus and the callus was treated with or without GA₄. SLR1 was co-immnoprecipitated with GID1-GFP protein only from GA₄-treated callus, which indicated that GID1 also interacts with SLR1 in vivo in GA dependent manner.