Structure-guided engineering of a receptor-agonist pair for inducible activation of the ABA adaptive response to drought

Abstract

Strategies to activate abscisic acid (ABA) receptors and boost ABA signaling by small molecules that act as ABA receptor agonists are promising biotechnological tools to enhance plant drought tolerance. Protein structures of crop ABA receptors might require modifications to improve recognition of chemical ligands, which in turn can be optimized by structural information. Through structure-based targeted design, we have combined chemical and genetic approaches to generate an ABA receptor agonist molecule (iSB09) and engineer a CsPYL1 ABA receptor, named CsPYL1 5m , which efficiently binds iSB09. This optimized receptor-agonist pair leads to activation of ABA signaling and marked drought tolerance. No constitutive activation of ABA signaling and hence growth penalty was observed in transformed Arabidopsis thaliana plants. Therefore, conditional and efficient activation of ABA signaling was achieved through a chemical-genetic orthogonal approach based on iterative cycles of ligand and receptor optimization driven by the structure of ternary receptor-ligand-phosphatase complexes.

A Potential ABA Analog to Increase Drought Tolerance in Arabidopsis thaliana

“…At present, multiple ABA analogs, such as AM1 [14], AMF4 [27], julolidine-and fluorine-containing ABA receptor activator (JFA1 and JFA2) [31], opabactin [18], and iSB09 [19], have a sulfonamide group, and their sulfonamide group resembles the carboxylate group of ABA. Combining yeast two-hybrid assays and PP2C inhibition experiments, it was found that SLG1 is mainly an agonist of PYL2 and PYL3.…”

“…Vaidya et al used virtual screening technologies combined with X-ray crystallography and structural designing to develop an amide compound opabactin, whose activity is ten-fold higher than ABA in both monocotyledonous and dicotyledonous plants from 18 million compounds [18]. Recently, through structural targeted design and structural modification, a sulfonamide sulfobactin (SB) derivative iSB09 was identified as an ABA agonist for the engineered CsPYL1 ABA receptor, named CsPYL15m CsPYL1 5m [19]. Therefore, the use of virtual screening technology to develop new ABA analogues is of great significance for improving the drought tolerance of crops.…”

Synthesis, Plant Growth Regulatory Activity, and Transcriptome Analysis of Novel Opabactin Analogs

“…The second category of ABA receptor selective agonists is characterized by a sulfonamide moiety serving as a linker arm. This group has garnered significant attention recently with examples such as pyrabactin, quinabctin, AMF4, cyanabactin, and the newly developed iSB-09 (Figure ). The crystal complexes of these sulfonamide ABA receptor agonists with PYLs show that their sulfonamide linker arm mimics the functional role of the carboxyl group in ABA. , Among these compounds, AMF4, derived from quinabctin, exhibits the highest potency and long-lasting effects in inducing drought tolerance in A.…”

Genome-Wide Identification of PYL/RCAR ABA Receptors and Functional Analysis of LbPYL10 in Heat Tolerance in Goji (Lycium barbarum)

“…Genetic modification the coding genes of PYL/RCAR ABA receptors can improve plant water use efficiency in Arabidopsis , wheat, and maize, presenting a prospective target for engineering drought–tolerant crops under changing environmental conditions [ 10 , 11 , 12 ]. Moreover, chemical manipulation of ABA signaling by ABA agonists [ 13 , 14 ] and direct modification of PYL/RCAR ABA receptors by protein engineering [ 15 ] all have significant agricultural and ecological applications.…”