title: Complex structures of the abscisic acid receptor PYL3/RCAR13 reveal a unique regulatory mechanism.
abstract: Abscisic acid (ABA) controls many physiological processes and mediates adaptive responses to abiotic stresses. The ABA signaling mechanisms for abscisic acid receptors PYR/PYL/RCAR (PYLs) were reported. However, it remains unclear whether the molecular mechanisms are suitable for other PYLs. Here, complex structures of PYL3 with (+)-ABA, pyrabactin and HAB1 are reported. An unexpected trans-homodimer intermediate observed in the crystal is confirmed in solution. ABA-bound PYL3 greatly promotes the generation of monomeric PYL3, which can excessively increase the efficiency of inhibiting PP2Cs. Structure-guided biochemical experiments show that Ser195 accounts for the key intermediate. Interestingly, pyrabactin binds to PYL3 in a distinct nonproductive mode with gate closure, which sheds light on the design of agonists and antagonists for abscisic acid receptors. According to different conformations of ligand-bound PYLs, the PYLs family can be divided into three subclasses, among which the trans-dimeric subclass, represented by PYL3, reveals a distinct regulatory mechanism.
authors.affiliation: State Key Laboratory of Agrobiotechnology, China Agricultural University, Beijing 100193, China.
authors.forename: Xingliang
authors.initials: X
authors.lastname: Zhang
authors.forename: Qi
authors.initials: Q
authors.lastname: Zhang
authors.forename: Qi
authors.initials: Q
authors.lastname: Xin
authors.forename: Lin
authors.initials: L
authors.lastname: Yu
authors.forename: Zheng
authors.initials: Z
authors.lastname: Wang
authors.forename: Wei
authors.initials: W
authors.lastname: Wu
authors.forename: Lun
authors.initials: L
authors.lastname: Jiang
authors.forename: Guoqiang
authors.initials: G
authors.lastname: Wang
authors.forename: Wenli
authors.initials: W
authors.lastname: Tian
authors.forename: Zengqin
authors.initials: Z
authors.lastname: Deng
authors.forename: Yang
authors.initials: Y
authors.lastname: Wang
authors.forename: Zhao
authors.initials: Z
authors.lastname: Liu
authors.forename: Jiafu
authors.initials: J
authors.lastname: Long
authors.forename: Zhizhong
authors.initials: Z
authors.lastname: Gong
authors.forename: Zhongzhou
authors.initials: Z
authors.lastname: Chen
mesh_terms: D000040:Abscisic Acid / Q000737:chemistry / Q000378:metabolism*; D017360:Arabidopsis / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000737:chemistry* / Q000378:metabolism; D001665:Binding Sites; D018360:Crystallography, X-Ray; D019281:Dimerization; D008024:Ligands; D008958:Models, Molecular; D009281:Naphthalenes / Q000737:chemistry / Q000378:metabolism; D010749:Phosphoprotein Phosphatases / Q000737:chemistry / Q000378:metabolism; D011487:Protein Conformation; D011956:Receptors, Cell Surface / Q000737:chemistry* / Q000378:metabolism; D015398:Signal Transduction; D013449:Sulfonamides / Q000737:chemistry / Q000378:metabolism
chemical_list: D029681:Arabidopsis Proteins; D008024:Ligands; D009281:Naphthalenes; C572912:PYL3 protein, Arabidopsis; D011956:Receptors, Cell Surface; D013449:Sulfonamides; C540973:pyrabactin; D000040:Abscisic Acid; C514757:HAB1 protein, Arabidopsis; D010749:Phosphoprotein Phosphatases