BPM-CUL3 E3 ligase modulates thermotolerance by facilitating negative regulatory domain-mediated degradation of DREB2A in Arabidopsis

Significance DEHYDRATION-RESPONSIVE ELEMENT-BINDING PROTEIN 2A (DREB2A) is a key transcription factor for plant adaptation to drought and heat. DREB2A activity is strictly regulated via proteolysis mediated by the negative regulatory domain (NRD), although the molecular basis for this regulation has remained unclear for a decade. We reveal that BTB/POZ AND MATH DOMAIN proteins (BPMs), substrate adaptors for Cullin3-based E3 ubiquitin ligase, are the long-sought factors responsible for NRD-dependent DREB2A degradation. Through DREB2A degradation, BPMs negatively regulate the heat stress response and prevent the adverse effects of excess DREB2A on plant growth. Furthermore, we found the BPM recognition motif in various transcription factors, implying a general contribution of BPM-mediated proteolysis to divergent cellular responses via an accelerated turnover of transcription factors.