title: Structural basis for gibberellin recognition by its receptor GID1.
abstract: Gibberellins (GAs) are phytohormones essential for many developmental processes in plants. A nuclear GA receptor, GIBBERELLIN INSENSITIVE DWARF1 (GID1), has a primary structure similar to that of the hormone-sensitive lipases (HSLs). Here we analyse the crystal structure of Oryza sativa GID1 (OsGID1) bound with GA(4) and GA(3) at 1.9 A resolution. The overall structure of both complexes shows an alpha/beta-hydrolase fold similar to that of HSLs except for an amino-terminal lid. The GA-binding pocket corresponds to the substrate-binding site of HSLs. On the basis of the OsGID1 structure, we mutagenized important residues for GA binding and examined their binding activities. Almost all of them showed very little or no activity, confirming that the residues revealed by structural analysis are important for GA binding. The replacement of Ile 133 with Leu or Val-residues corresponding to those of the lycophyte Selaginella moellendorffii GID1s-caused an increase in the binding affinity for GA(34), a 2beta-hydroxylated GA(4). These observations indicate that GID1 originated from HSL and was further modified to have higher affinity and more strict selectivity for bioactive GAs by adapting the amino acids involved in GA binding in the course of plant evolution.
authors.affiliation: Bioscience and Biotechnology Center, Nagoya University, Nagoya, Aichi 464-8601, Japan.
authors.forename: Asako
authors.initials: A
authors.lastname: Shimada
authors.forename: Miyako
authors.initials: M
authors.lastname: Ueguchi-Tanaka
authors.forename: Toru
authors.initials: T
authors.lastname: Nakatsu
authors.forename: Masatoshi
authors.initials: M
authors.lastname: Nakajima
authors.forename: Youichi
authors.initials: Y
authors.lastname: Naoe
authors.forename: Hiroko
authors.initials: H
authors.lastname: Ohmiya
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Kato
authors.forename: Makoto
authors.initials: M
authors.lastname: Matsuoka
mesh_terms: D001665:Binding Sites; D018360:Crystallography, X-Ray; D005875:Gibberellins / Q000737:chemistry* / Q000378:metabolism*; D006867:Hydrolases / Q000737:chemistry / Q000378:metabolism; D006900:Hydroxylation; D008958:Models, Molecular; D012275:Oryza / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D010937:Plant Growth Regulators / Q000737:chemistry* / Q000378:metabolism*; D010940:Plant Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D011485:Protein Binding; D011487:Protein Conformation; D013379:Substrate Specificity; D020798:Two-Hybrid System Techniques
chemical_list: D005875:Gibberellins; D010937:Plant Growth Regulators; D010940:Plant Proteins; D006867:Hydrolases