A missense mutation in C. elegans RAD-54, a homolog of RAD54 that operates in the homologous recombination (HR) pathway, was found to decrease ATPase activity in vitro. The hypomorphic mutation caused hypersensitivity of C. elegans germ cells to double-strand DNA breaks (DSBs). Although the formation of RAD-51 foci at DSBs was normal in both the mutant and knockdown worms, their subsequent dissipation was slow. The rad-54-deficient phenotypes were greatly aggravated when combined with an xpf-1 mutation, suggesting a conservative role of single-strand annealing (SSA) for DSB repair in HR-defective worms. The phenotypes of doubly-deficient rad-54;xpf-1 worms were partially suppressed by a mutation of lig-4, a nonhomologous end-joining (NHEJ) factor. In summary, RAD-54 is required for the dissociation of RAD-51 from DSB sites in C. elegans germ cells. Also, NHEJ and SSA exert negative and positive effects, respectively, on genome stability when HR is defective.
Bibliographical noteFunding Information:
This work was supported by The National Research Foundation of Korea [the Basic Science Research program, 2016R1D1A1B03934743 to H.-S.K.]; the Brain Korea 21 ( BK21 ) PLUS program.
The wild-type Bristol N2, lig-4(ok716), xpa-1(ok698), and VC20429 [containing rad-54(gk118019) allele] strains were acquired from the C. elegans Genetics Center (St Paul, MN, USA), which is funded by the NIH Office of Research Infrastructure Programs ( P40 OD010440 ). We thank Dr. Shohei Mitani (Tokyo Women’s Medical University School of Medicine) for the xpf-1(tm2842), xpc-1(tm3886), and polq-1(tm2572) mutants, and Dr. Hannes Lans (Erasmus Medical Center, Netherlands) for sending outcrossed ercc-1(tm2073) worms. We also thank Dr. George Chung (University of British Columbia, Canada) for reading this manuscript and providing helpful comments. We very much appreciated the technical assistance of Sin-Ae Oh (Yonsei University, Republic of Korea).
All Science Journal Classification (ASJC) codes
- Molecular Biology
- Cell Biology