The DNA‐dependent protease AtWSS1A suppresses persistent double strand break formation during replication

Abstract

The protease WSS1A is an important factor in the repair of DNA-protein crosslinks in plants.Here we show that the loss of WSS1A leads to a reduction of 45S rDNA repeats and chromosomal fragmentation in Arabidopsis. Moreover, in the absence of any factor of the RTR (RECQ4A/TOP3a/RMI1/2) complex, which is involved in the dissolution of DNA replication intermediates, WSS1A becomes essential for viability.If WSS1A loss is combined with loss of the classical (c) or alternative (a) nonhomologous end joining (NHEJ) pathways of double-strand break (DSB) repair, the resulting mutants show proliferation defects and enhanced chromosome fragmentation, which is especially aggravated in the absence of aNHEJ. This indicates that WSS1A is involved either in the suppression of DSB formation or in DSB repair itself. To test the latter we induced DSB by CRISPR/Cas9 at different loci in wild-type and mutant cells and analyzed their repair by deep sequencing. However, no change in the quality of the repair events and only a slight increase in their quantity was found.Thus, by removing complex DNA-protein structures, WSS1A seems to be required for the repair of replication intermediates which would otherwise be resolved into persistent DSB leading to genome instability.

Deficiency of both classical and alternative end‐joining pathways leads to a synergistic defect in double‐strand break repair but not to an increase in homology‐dependent gene targeting in Arabidopsis

“…Moreover, loss of POLQ resulted in hypersensitivity to replication stress‐inducing agents, such as hydroxyurea or ATR inhibitors (Wang et al., 2019). Additionally, recent results in Arabidopsis indicate an important role of AtPOLQ in replicative repair (Hacker et al., 2022; Nisa et al., 2021).…”

“…Further analysis by the same authors revealed that double mutants in factors involved in HR showed severe growth defects, indicating that AtPOLQ acts in a parallel pathway to HR to safeguard cell proliferation (Inagaki et al., 2009). Just recently, studies have indicated that POLQ is mandatory in avoiding accumulation of DNA damage during DNA replication (Hacker et al., 2022; Nisa et al., 2021). Additionally, POLQ is essential for T‐DNA integration in Arabidopsis.…”

Genomic divergence between two sister Medicago species triggered by the quaternary climatic oscillations on the Qinghai–Tibet plateau and northern China

“…The identified genes may be related to environmental conditions (i.e., response to high altitude, drought and salinity) and reproductive divergence (e.g., pollen tube growth and flowering) between the two species (Table S7). For example, among significantly divergent genes with selection signatures, we found four ( GRF4 , PSUT , FTSHI and PIF1 ) related to cold response (Jiang et al, 2020; Lantzouni et al, 2020; Li et al, 2022; Patzke et al, 2019) and six ( RAD23C , CHR24 , ALY3 , RECQ4A , RAD7 and BSD ) associated with nucleotide excision‐repair and DNA‐damage tolerance (Hacker et al, 2022; Kunz et al, 2005; Lahari et al, 2018; Lang et al, 2021; Shaked et al, 2006). These genes may be important for the adaptation of M. archiducis‐nicolai to high‐altitude environments.…”

“…and BSD) associated with nucleotide excision-repair and DNAdamage tolerance (Hacker et al, 2022;Kunz et al, 2005;Lahari et al, 2018;Lang et al, 2021;Shaked et al, 2006). These genes may be important for the adaptation of M. archiducis-nicolai to high-altitude environments.…”