The ribonuclease domain function is dispensable for SLFN11 to mediate cell fate decision during replication stress...

The SLFN11 gene participates in cell fate decision following cancer chemotherapy and encodes the N-terminal ribonuclease (RNase) domain and the C-terminal helicase/ATPase domain. How these domains contribute to the chemotherapeutic response remains controversial. Here, we expressed SLFN11 containing mutations in two critical residues required for RNase activity in SLFN11^-/- cells. We found that this mutant was still able to suppress DNA damage tolerance, destabilized the stalled replication forks, and perturbed recruitment of the fork protector RAD51. In contrast, we confirmed that the helicase domain was essential to accelerate fork degradation. The fork degradation by the RNase mutant was dependent on both DNA2 and MRE11 nuclease, but not on MRE11's novel interactor FXR1. Collectively, these results supported the view that the RNase domain function is dispensable for SLFN11 to mediate cell fate decision during replication stress response.