Click-to-lead design of a picomolar ABA receptor antagonist with potent activity in vivo. Proc Natl Acad Sci U S A 2021 Sep 21;118(38)
Date
09/18/2021Pubmed ID
34531324Pubmed Central ID
PMC8463862DOI
10.1073/pnas.2108281118Scopus ID
2-s2.0-85115276330 (requires institutional sign-in at Scopus site) 37 CitationsAbstract
Abscisic acid (ABA) is a key plant hormone that mediates both plant biotic and abiotic stress responses and many other developmental processes. ABA receptor antagonists are useful for dissecting and manipulating ABA's physiological roles in vivo. We set out to design antagonists that block receptor-PP2C interactions by modifying the agonist opabactin (OP), a synthetically accessible, high-affinity scaffold. Click chemistry was used to create an ∼4,000-member library of C4-diversified opabactin derivatives that were screened for receptor antagonism in vitro. This revealed a peptidotriazole motif shared among hits, which we optimized to yield antabactin (ANT), a pan-receptor antagonist. An X-ray crystal structure of an ANT-PYL10 complex (1.86 Å) reveals that ANT's peptidotriazole headgroup is positioned to sterically block receptor-PP2C interactions in the 4' tunnel and stabilizes a noncanonical closed-gate receptor conformer that partially opens to accommodate ANT binding. To facilitate binding-affinity studies using fluorescence polarization, we synthesized TAMRA-ANT. Equilibrium dissociation constants for TAMRA-ANT binding to Arabidopsis receptors range from ∼400 to 1,700 pM. ANT displays improved activity in vivo and disrupts ABA-mediated processes in multiple species. ANT is able to accelerate seed germination in Arabidopsis, tomato, and barley, suggesting that it could be useful as a germination stimulant in species where endogenous ABA signaling limits seed germination. Thus, click-based diversification of a synthetic agonist scaffold allowed us to rapidly develop a high-affinity probe of ABA-receptor function for dissecting and manipulating ABA signaling.
Author List
Vaidya AS, Peterson FC, Eckhardt J, Xing Z, Park SY, Dejonghe W, Takeuchi J, Pri-Tal O, Faria J, Elzinga D, Volkman BF, Todoroki Y, Mosquna A, Okamoto M, Cutler SRAuthors
Francis C. Peterson PhD Professor in the Biochemistry department at Medical College of WisconsinBrian F. Volkman PhD Professor in the Biochemistry department at Medical College of Wisconsin
MESH terms used to index this publication - Major topics in bold
Abscisic AcidArabidopsis
Arabidopsis Proteins
Benzamides
Carrier Proteins
Click Chemistry
Cyclohexanes
Gene Expression
Germination
Models, Molecular
Plant Growth Regulators
Quinolines
Seeds
Signal Transduction
Stress, Physiological
Triazoles
