A plant-specific module for homologous recombination repair

Author: Xuanpeng Wang, Lili Wang, Yongchi Huang, Zhiping Deng, Cunliang Li, Jian Zhang, Mingxi Zheng, and Shunping Yan

PNAS. April 11 2022.  Vol. 119  No.16

Abstract: Homologous recombination repair (HR) is an error-free DNA damage repair pathway to maintain genome stability and a basis of gene targeting using genome-editing tools. However, the mechanisms of HR in plants are still poorly understood. Through genetic screens for DNA Damage Response Mutants (DDRM) in Arabidopsis, we find that a plant-specific ubiquitin E3 ligase DDRM1 is required for HR. DDRM1 contains an N-terminal BRCT (BRCA1 C-terminal) domain and a C-terminal RING (Really Interesting New Gene) domain and is highly conserved in plants including mosses. The ddrm1 mutant is defective in HR and thus is hypersensitive to DNA-damaging reagents. Biochemical studies reveal that DDRM1 interacts with and ubiquitinates the transcription factor SOG1, a plant-specific master regulator of DNA damage responses. Interestingly, DDRM1-mediated ubiquitination promotes the stability of SOG1. Consistently, genetic data support that SOG1 functions downstream of DDRM1. Our study reveals that DDRM1-SOG1 is a plant-specific module for HR and highlights the importance of ubiquitination in HR.

Full Article:https://www.pnas.org/doi/10.1073/pnas.2202970119