title: Single amino acid alteration between valine and isoleucine determines the distinct pyrabactin selectivity by PYL1 and PYL2.
abstract: Abscisic acid (ABA) is one of the most important phytohormones in plant. PYL proteins were identified to be ABA receptors in Arabidopsis thaliana. Despite the remarkably high degree of sequence similarity, PYL1 and PYL2 exhibit distinct responses toward pyrabactin, an ABA agonist. PYL1 inhibits protein phosphatase type 2C upon binding of pyrabactin. In contrast, PYL2 appears relatively insensitive to this compound. The crystal structure of pyrabactin-bound PYL1 revealed that most of the PYL1 residues involved in pyrabactin binding are conserved, hence failing to explain the selectivity of pyrabactin for PYL1 over PYL2. To understand the molecular basis of pyrabactin selectivity, we determined the crystal structure of PYL2 in complex with pyrabactin at 1.64 A resolution. Structural comparison and biochemical analyses demonstrated that one single amino acid alteration between a corresponding valine and isoleucine determines the distinct pyrabactin selectivity by PYL1 and PYL2. These characterizations provide an important clue to dissecting the redundancy of PYL proteins.
authors.affiliation: State Key Laboratory of Biomembrane and Membrane Biotechnology, Center for Structural Biology, School of Medicine and School of Life Sciences, Tsinghua University, Beijing 100084, China.
authors.forename: Xiaoqiu
authors.initials: X
authors.lastname: Yuan
authors.forename: Ping
authors.initials: P
authors.lastname: Yin
authors.forename: Qi
authors.initials: Q
authors.lastname: Hao
authors.forename: Chuangye
authors.initials: C
authors.lastname: Yan
authors.forename: Jiawei
authors.initials: J
authors.lastname: Wang
authors.forename: Nieng
authors.initials: N
authors.lastname: Yan
mesh_terms: D000040:Abscisic Acid / Q000819:agonists / Q000737:chemistry / Q000378:metabolism; D017360:Arabidopsis / Q000737:chemistry* / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000737:chemistry* / Q000378:metabolism; D018360:Crystallography, X-Ray; D007532:Isoleucine / Q000737:chemistry* / Q000378:metabolism; D017434:Protein Structure, Tertiary; D011956:Receptors, Cell Surface / Q000737:chemistry* / Q000378:metabolism; D014633:Valine / Q000737:chemistry* / Q000378:metabolism
chemical_list: D029681:Arabidopsis Proteins; D011956:Receptors, Cell Surface; D007532:Isoleucine; D000040:Abscisic Acid; D014633:Valine