Seminario impartido por Vicente Rubio, del Centro Nacional de Biotecnología
The plant hormone abscisic acid (ABA) regulates key developmental processes, including seed germination, and responses to abiotic stresses, including drought and salinity. ABA is perceived by PYR/PYL/RCAR receptors, among which, PYL8 plays a prominent role in enabling responses to ABA in Arabidopsis. We previously showed that PYL8 abundance is controlled by the ubiquitin-proteasome system, which involves specific recognition and ubiquitination of PYL8 by the CRL4-CDDD type of CULLIN4-RING E3 ubiquitin ligases. Conversely, ABA treatments attenuate PYL8 receptor degradation, although the precise molecular details of this mechanism remained unknown. Recently, we have unveiled the mechanism underlying ABA inhibition of CUL4-CDDD and stabilization of PYL8. We found that ABA protects PYL8 by promoting the disassembly and inactivation of CRL4-CDDD complexes. Therefore, increased PYL8 accumulation in the presence of ABA reinforces and sustains ABA signaling. Our studies unveil a molecular mechanism by which a hormone directly inactivates an E3 ligase in order to stabilize its own receptors. This is an unprecedented mechanism and is opposite to what has been reported for other plant hormones, such as auxins and jasmonate, where hormone binding to its receptor promotes the assembly of CRL E3 ligase complexes and the degradation of targets; i.e. repressors of hormone signaling such as IAA and JAZ proteins, respectively.
Ponente del seminario: Vicente Rubio
Fecha del seminario: 17/04/2024 12:00
Lugar del seminario: salón de actos IQF
