Updated project metadata.
Phytohormone abscisic acid (ABA) regulates key aspects of plant development such as seed germination, as well as responses to important environmental stresses, including drought, salinity and cold temperatures. The ABA signaling pathway is tightly controlled by the ubiquitin proteasome system. CULLIN4-RING E3 ubiquitin ligases use the substrate receptor module COP10-DDB1-DET1-DDA1 (CDDD) to target PYL8, one of the ABA receptors of the PYR/PYL/RCAR (pyrabactin resistance/pyrabactin resistance-like/regulatory components of ABA) family. Therefore, CRL4-CDDD complexes are negative regulators of ABA-mediated stress responses. Conversely, ABA treatments attenuate PYL8 receptor degradation, although the precise molecular details of this mechanism remained unknown. Here, we show that ABA promotes the disruption of CRL4-CDDD complexes, leading to PYL8 stabilization. ABA-mediated CRL4-CDDD dissociation likely involves altered association between DDA1-containing complexes and the CSN, a master regulator of the assembly of cullin-based E3 ligases, including CRL4-CDDD. Indeed, treatments with CSN5i-3, an inhibitor of the CSN activity, suppressed the ABA effect on CRL4-CDDD assembly. Altogether, our findings indicate that ABA stabilizes PYL8 by altering the dynamics of the CRL4-CDDD-CSN complex association, unveiling a regulatory mechanism by which a plant hormone inhibits an E3 ubiquitin ligase to protect its own receptors from degradation.