title: Structural basis for differential recognition of brassinolide by its receptors.
abstract: Brassinosteroids, a group of plant steroid hormones, regulate many aspects of plant growth and development. We and other have previously solved the crystal structures of BRI1(LRR) in complex with brassinolide, the most active brassinosteroid identified thus far. Although these studies provide a structural basis for the recognition of brassinolide by its receptor BRI1, it still remains poorly understood how the hormone differentiates among its conserved receptors. Here we present the crystal structure of the BRI1 homolog BRL1 in complex with brassinolide. The structure shows that subtle differences around the brassinolide binding site can generate a striking effect on its recognition by the BRI1 family of receptors. Structural comparison of BRL1 and BRI1 in their brassinolide-bound forms reveals the molecular basis for differential binding of brassinolide to its different receptors, which can be used for more efficient design of plant growth regulators for agricultural practice. On the basis of our structural studies and others' data, we also suggest possible mechanisms for the activation of BRI1 family receptors.
authors.affiliation: School of Life Sciences, Peking University, Beijing, 100871, China.
authors.forename: Ji
authors.initials: J
authors.lastname: She
authors.forename: Zhifu
authors.initials: Z
authors.lastname: Han
authors.forename: Bin
authors.initials: B
authors.lastname: Zhou
authors.forename: Jijie
authors.initials: J
authors.lastname: Chai
mesh_terms: D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000737:chemistry* / Q000378:metabolism; D001665:Binding Sites; D060406:Brassinosteroids / Q000737:chemistry*; D018360:Crystallography, X-Ray; D008969:Molecular Sequence Data; D011494:Protein Kinases / Q000737:chemistry* / Q000378:metabolism; D017434:Protein Structure, Tertiary; D011994:Recombinant Proteins / Q000235:genetics; D016415:Sequence Alignment; D013260:Steroids, Heterocyclic / Q000737:chemistry*
chemical_list: D029681:Arabidopsis Proteins; D060406:Brassinosteroids; D011994:Recombinant Proteins; D013260:Steroids, Heterocyclic; D011494:Protein Kinases; C108270:BRI1 protein, Arabidopsis; C023623:brassinolide