Molecular Interactions of a Soluble Gibberellin Receptor, GID1, with a Rice DELLA Protein, SLR1, and Gibberellin

Abstract

GIBBERELLIN INSENSITIVE DWARF1 (GID1) encodes a soluble gibberellin (GA) receptor that shares sequence similarity with a hormone-sensitive lipase (HSL). Previously, a yeast two-hybrid (Y2H) assay revealed that the GID1-GA complex directly interacts with SLENDER RICE1 (SLR1), a DELLA repressor protein in GA signaling. Here, we demonstrated, by pulldown and bimolecular fluorescence complementation (BiFC) experiments, that the GA-dependent GID1-SLR1 interaction also occurs in planta. GA 4 was found to have the highest affinity to GID1 in Y2H assays and is the most effective form of GA in planta. Domain analyses of SLR1 using Y2H, gel filtration, and BiFC methods revealed that the DELLA and TVHYNP domains of SLR1 are required for the GID1-SLR1 interaction. To identify the important regions of GID1 for GA and SLR1 interactions, we used many different mutant versions of GID1, such as the spontaneous mutant GID1s, N-and C-terminal truncated GID1s, and mutagenized GID1 proteins with conserved amino acids replaced with Ala. The amino acid residues important for SLR1 interaction completely overlapped the residues required for GA binding that were scattered throughout the GID1 molecule. When we plotted these residues on the GID1 structure predicted by analogy with HSL tertiary structure, many residues were located at regions corresponding to the substrate binding pocket and lid. Furthermore, the GA-GID1 interaction was stabilized by SLR1. Based on these observations, we proposed a molecular model for interaction between GA, GID1, and SLR1.

Reduction of Gibberellin by Low Temperature Disrupts Pollen Development in Rice

“…All GA-insensitive mutants, including gid1-8 (Ueguchi- Tanaka et al, 2007) and the gain-of-function SLR1 mutants (slr1-d1, slr1-d2, slr1-d3, and slr1-d4; Asano et al, 2009), were hypersensitive to cool temperatures and exhibit severe disruptions of pollen development at LT. Figure 6 shows the results using gid1-8, slr1-d1, and slr1-d3 mutants in the Taichung 65 (TC65) background (Fig. 6, A-C).…”

“…The sd1 mutant is considered one of the greatest achievements of the Green Revolution (Monna et al, 2002;Sasaki et al, 2002). In addition, we studied the response to LT in other GA biosynthesis mutants, including dwarf Tan-Ginbozu (d35; Suge, 1975;Itoh et al, 2004), the gain-of-function slender rice1 (slr1-d) mutant (Asano et al, 2009), and the GAinsensitive gibberellin insensitive dwarf1 (gid1) mutant (Ueguchi-Tanaka et al, 2007). We also explored potential remedial strategies for LT damage by examining the effects of GA application on pollen development under cool-temperature conditions.…”

The Gibberellin perception system evolved to regulate a pre-existing GAMYB-mediated system during land plant evolution

“…Previous anatomical and in silico studies suggest that, similar to flowering plants, present-day bryophytes, including mosses, and lycophytes (lycopods) contain sporopollenin-containing outer walls on the surface of their spores and microspores [9][10][11] , and genes encoding CYP703 homologues have been detected in these genomes 12 . Curiously, however, one of the basal vascular plants, Selaginella, contains a functional GA perception system that is mediated by a GA receptor, GIBBERELLIN-INSENSITIVE DWARF1 (GID1), and suppressor proteins (DELLAs), whereas one of the basal land plants, Physcomitrella patens, does not contain this system [13][14][15][16] . These observations led us to speculate that the ancestral land plants developed sporopollenin-containing outer walls on their spores, which protected the spores from dryness and ultraviolet radiation on land, in association with CYP703-like enzymes, and that GA signalling pathway then evolved to control the development of the spore outer wall via the modulation of CYP703-like expressions during the evolution from mosses to lycopods.…”

Endogenous Diterpenes Derived from ent-Kaurene, a Common Gibberellin Precursor, Regulate Protonema Differentiation of the Moss Physcomitrella patens

“…The active GAs can bind to the soluble GA receptor, GID1, and promote the interaction of GID1 with DELLA repressors, which are negative regulators of GA signaling (Ueguchi-Tanaka et al, 2005;Nakajima et al, 2006). This GA-promoted GID1-DELLA interaction triggers the degradation of DELLA repressors via the SCF GID2/SLY1 proteasome pathway and consequently activates GA signaling (Ueguchi-Tanaka et al, 2007).…”