A plant-specific module for homologous recombination repair (PNAS)

Damage to DNA occurs through exposure to environmental stresses in animal and plant kingdoms alike. While the former groups are relatively well explored when it comes to DNA damage response (DDR) mechanisms, plant-related knowledge lags behind. A recent study by Wang et al. revealed a unique plant DDR protein identified through genetic screens of the TRANSPLANTA collection containing 1,636 homozygous Arabidopsis thaliana lines. The screen identified the DNA damage response ddrm1 mutant which was sensitive to DNA damage-inducing reagents. DDRM1 is conserved in land plants and encodes a nuclear localized protein. Using split luciferase and BiFC assays, DDRM1 was confirmed to interact with the DDR master regulator transcription factor SOG1, leading to its ubiquitination. Mono-ubiquitination of SOG1 at numerous lysine residues leads to its subsequent stabilization, influencing the ability of SOG1 to mediate cell cycle arrest, DNA repair and cell death. This study enhances our understanding of plant specific DNA damage responses and posttranslational regulation of this critical DDR pathway. (Summary by Orla Sherwood, @orlasherwood) PNAS. 10.1073/pnas.2202970119