Abscisic Acid Inhibits Type 2C Protein Phosphatases via the PYR/PYL Family of START Proteins

: Park, Sang-Youl; Fung, Pauline; Nishimura, Noriyuki; Jensen, Davin R.; Fujii, Hiroaki; Zhao, Yang; Lumba, Shelley; Santiago, Julia; Rodrigues, Americo; Chow, Tsz-Fung F.; Alfred, Simon E.; Bonetta, Dario; Finkelstein, Ruth; Provart, Nicholas J.; Desveaux, Darrell; Rodriguez, Pedro L.; McCourt, Peter; Zhu, Jian-Kang; Schroeder, Julian I.; Volkman, Brian F.; Cutler, Sean R.

Publisher: AMER ASSOC ADVANCEMENT SCIENCE

: WASHINGTON

: 2009

: Science

: SCIENCE

: 324

: 5930

: 1068

: 1071

: 4

: 0036-8075

: 1095-9203

DOI: https://doi.org/10.1126/science.1173041

Type 2C protein phosphatases (PP2Cs) are vitally involved in abscisic acid (ABA) signaling. Here, we show that a synthetic growth inhibitor called pyrabactin functions as a selective ABA agonist. Pyrabactin acts through PYRABACTIN RESISTANCE 1 (PYR1), the founding member of a family of START proteins called PYR/PYLs, which are necessary for both pyrabactin and ABA signaling in vivo. We show that ABA binds to PYR1, which in turn binds to and inhibits PP2Cs. We conclude that PYR/PYLs are ABA receptors functioning at the apex of a negative regulatory pathway that controls ABA signaling by inhibiting PP2Cs. Our results illustrate the power of the chemical genetic approach for sidestepping genetic redundancy.