Post-translational modifications of SOG1 enable dynamic control of plant DNA damage response

DNA damage response (DDR) is essential for maintaining genome stability and thus is tightly controlled to prevent misactivation in the absence of DNA damage and to ensure rapid activation when DNA damage occurs. Although the mechanisms of DDR activation have been extensively studied, how DDR is kept inactive is far less well understood, especially in plants. Here, we show that the plant-specific transcription factor SOG1, a master regulator of the plant DDR, interacts with PRL1, which functions as a substrate adaptor of the Cullin4-based E3 ubiquitin ligase CRL4^PRL1 to polyubiquitinate SOG1, promoting SOG1 degradation through 26S proteasome. When DNA damage occurs, PRL1 is degraded and SOG1 is phosphorylated, both of which impair the polyubiquitination and degradation of SOG1. This study demonstrated that plants dynamically control DDR by regulating the phosphorylation and polyubiquitination of SOG1.