Characterization of the molecular mechanism underlying gibberellin perception complex formation in rice.
The DELLA protein SLENDER RICE1 (SLR1) is a repressor of gibberellin (GA) signaling in rice (Oryza sativa), and most of the GA-associated responses are induced upon SLR1 degradation. It is assumed that interaction between GIBBERELLIN INSENSITIVE DWARF1 (GID1) and the N-terminal DELLA/TVHYNP motif of SLR1 triggers F-box protein GID2-mediated SLR1 degradation. We identified a semidominant dwarf mutant, Slr1-d4, which contains a mutation in the region encoding the C-terminal GRAS domain of SLR1 (SLR1(G576V)). The GA-dependent degradation of SLR1(G576V) was reduced in Slr1-d4, and compared with SLR1, SLR1(G576V) showed reduced interaction with GID1 and almost none with GID2 when tested in yeast cells. Surface plasmon resonance of GID1-SLR1 and GID1-SLR1(G576V) interactions revealed that the GRAS domain of SLR1 functions to stabilize the GID1-SLR1 interaction by reducing its dissociation rate and that the G576V substitution in SLR1 diminishes this stability. These results suggest that the stable interaction of GID1-SLR1 through the GRAS domain is essential for the recognition of SLR1 by GID2. We propose that when the DELLA/TVHYNP motif of SLR1 binds with GID1, it enables the GRAS domain of SLR1 to interact with GID1 and that the stable GID1-SLR1 complex is efficiently recognized by GID2.
Hirano
Ko
K
Bioscience and Biotechnology Center, Nagoya University, Nagoya 464-8601, Japan.
Asano
Kenji
K
Tsuji
Hiroyuki
H
Kawamura
Mayuko
M
Mori
Hitoshi
H
Kitano
Hidemi
H
Ueguchi-Tanaka
Miyako
M
Matsuoka
Makoto
M
D018506:Gene Expression Regulation, Plant; D005875:Gibberellins / Q000378:metabolism*; D009154:Mutation; D012275:Oryza / Q000235:genetics* / Q000378:metabolism; D010937:Plant Growth Regulators / Q000378:metabolism*; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D030821:Plants, Genetically Modified / Q000235:genetics / Q000378:metabolism; D054730:Protein Interaction Domains and Motifs
D005875:Gibberellins; D010937:Plant Growth Regulators; D010940:Plant Proteins