The Roles of Rice RAD51 Paralogs in Somatic Homologous Recombination for DNA repair

【作者】 徐展； Jianxiang Zhang； Meng Xu； Wen Ji； Meimei Yu； Zhiyun Gong； Minghong Gu； 于恒秀；

【Author】 Zhan Xu;Jianxiang Zhang;Meng Xu;Wen Ji;Meimei Yu;Zhiyun Gong;Minghong Gu;Hengxiu Yu;Key Laboratory of Plant Functional Genomics of Ministry of Education,Jiangsu Key Laboratory of Crop Genetics and Physiology,Co-Innovation Center for Modern Production Technology of Grain Crops,Yangzhou University;

【机构】 Key Laboratory of Plant Functional Genomics of Ministry of Education,Jiangsu Key Laboratory of Crop Genetics and Physiology,Co-Innovation Center for Modern Production Technology of Grain Crops,Yangzhou University；

【摘要】 Synthesis-dependent strand annealing(SDSA) and single-strand annealing(SSA) are the two main homologous recombination(HR) pathways in double-strand break(DSB) repair.The involvement of rice RAD51 paralogs in HR is well known in meiosis,although the molecular mechanism in somatic HR remains obscure.Loss-of-function mutants of rad51 paralogs show increased sensitivity to the DSB-inducer bleomycin,which results in greatly compromised somatic recombination efficiencies(xrcc3 in SDSA,rad51 b and xrcc2 in SSA,radSlc and rad51 d’m both).Using immunostaining,we found that mutations in RAD51 paralogs(XRCC3,RAD51 C,or RAD51 D) lead to tremendous impairment in RAD51 focus formation at DSBs.Intriguingly,mutation of RAD51 C has a strong impact on the protein loading of its partners(XRCC3 and RAD5 IB) at DSBs,which is similar to the phenomenon observed in the case of blocking PDK-like kinases in wild-type plant.We conclude that the rice CDX3 complex acts in the SDSA recombination while the BCDX2 complex acts in the SSA recombination in somatic DSB repair.Importantly,RAD51 C serves as a fulcrum for the local recruitment of its partners(XRCC3 for SDSA and RAD51 B for SSA),and is positively modulated by PDK-like kinases,to facilitate both the SDSA and SSA pathways in RAD51 paralog-dependent somatic HR.更多还原

【Abstract】 Synthesis-dependent strand annealing(SDSA) and single-strand annealing(SSA) are the two main homologous recombination(HR) pathways in double-strand break(DSB) repair.The involvement of rice RAD51 paralogs in HR is well known in meiosis,although the molecular mechanism in somatic HR remains obscure.Loss-of-function mutants of rad51 paralogs show increased sensitivity to the DSB-inducer bleomycin,which results in greatly compromised somatic recombination efficiencies(xrcc3 in SDSA,rad51 b and xrcc2 in SSA,radSlc and rad51 d’m both).Using immunostaining,we found that mutations in RAD51 paralogs(XRCC3,RAD51 C,or RAD51 D) lead to tremendous impairment in RAD51 focus formation at DSBs.Intriguingly,mutation of RAD51 C has a strong impact on the protein loading of its partners(XRCC3 and RAD5 IB) at DSBs,which is similar to the phenomenon observed in the case of blocking PDK-like kinases in wild-type plant.We conclude that the rice CDX3 complex acts in the SDSA recombination while the BCDX2 complex acts in the SSA recombination in somatic DSB repair.Importantly,RAD51 C serves as a fulcrum for the local recruitment of its partners(XRCC3 for SDSA and RAD51 B for SSA),and is positively modulated by PDK-like kinases,to facilitate both the SDSA and SSA pathways in RAD51 paralog-dependent somatic HR.更多还原