Mammalian RAD51 paralogs protect nascent DNA at stalled forks and mediate replication restart.
Mammalian RAD51 paralogs are implicated in the repair of collapsed replication forks by homologous recombination. However, their physiological roles in replication fork maintenance prior to fork collapse remain obscure. Here, we report on the role of RAD51 paralogs in short-term replicative stress devoid of DSBs. We show that RAD51 paralogs localize to nascent DNA and common fragile sites upon replication fork stalling. Strikingly, RAD51 paralogs deficient cells exhibit elevated levels of 53BP1 nuclear bodies and increased DSB formation, the latter being attributed to extensive degradation of nascent DNA at stalled forks. RAD51C and XRCC3 promote the restart of stalled replication in an ATP hydrolysis dependent manner by disengaging RAD51 and other RAD51 paralogs from the halted forks. Notably, we find that Fanconi anemia (FA)-like disorder and breast and ovarian cancer patient derived mutations of RAD51C fails to protect replication fork, exhibit under-replicated genomic regions and elevated micro-nucleation. Taken together, RAD51 paralogs prevent degradation of stalled forks and promote the restart of halted replication to avoid replication fork collapse, thereby maintaining genomic integrity and suppressing tumorigenesis.
Department of Biochemistry, Indian Institute of Science, Bangalore-560012, India.
Kumar
K
Somyajit
Department of Biochemistry, Indian Institute of Science, Bangalore-560012, India.
Sneha
S
Saxena
Department of Biochemistry, Indian Institute of Science, Bangalore-560012, India.
Sharath
S
Babu
Department of Biochemistry, Indian Institute of Science, Bangalore-560012, India.
Anup
A
Mishra
Department of Biochemistry, Indian Institute of Science, Bangalore-560012, India nganesh@biochem.iisc.ernet.in.
Ganesh
G
Nagaraju
D020816:Amino Acid Motifs; D000818:Animals; D001943:Breast Neoplasms / Q000235:genetics; D002460:Cell Line; D002843:Chromatin / Q000378:metabolism; D043283:Chromosome Fragile Sites; D006224:Cricetinae; D003412:Cricetulus; D004247:DNA / Q000378:metabolism*; D053960:DNA Breaks; D004261:DNA Replication; D004277:DNA, Single-Stranded / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D004259:DNA-Directed DNA Polymerase; D051856:Fanconi Anemia Complementation Group Proteins / Q000378:metabolism; D005260:Female; D006367:HeLa Cells; D006801:Humans; D009097:Multienzyme Complexes; D009154:Mutation; D010051:Ovarian Neoplasms / Q000235:genetics; D016196:S Phase; D000099272:Replisomes
D002843:Chromatin; D004247:DNA; D004277:DNA, Single-Stranded; D004268:DNA-Binding Proteins; D004259:DNA-Directed DNA Polymerase; D051856:Fanconi Anemia Complementation Group Proteins; D009097:Multienzyme Complexes; D000099272:Replisomes; C448305:RAD51C protein, human; C110901:X-ray repair cross complementing protein 3; C113187:XRCC2 protein, human