The 9-1-1 DNA clamp is required for immunoglobulin gene conversion

Alihossein Saberi, Makoto Nakahara, Julian E. Sale, Koji Kikuchi, Hiroshi Arakawa, Jean Marie Buerstedde, Kenichi Yamamoto, Shunichi Takeda, Eiichiro Sonoda

Research output: Contribution to journalArticlepeer-review

23 Citations (Scopus)


Chicken DT40 cells deficient in the 9-1-1 checkpoint clamp exhibit hypersensitivity to a variety of DNA-damaging agents. Although recent work suggests that, in addition to its role in checkpoint activation, this complex may play a role in homologous recombination and translesion synthesis, the cause of this hypersensitivity has not been studied thoroughly. The immunoglobulin locus of DT40 cells allows monitoring of homologous recombination and translesion synthesis initiated by activation-induced deaminase (AID)-dependent abasic sites. We show that both the RAD9-/- and RAD17-/- mutants exhibit substantially reduced immunoglobulin gene conversion. However, the level of nontemplated immunoglobulin point mutation increased in these mutants, a finding that is reminiscent of the phenotype resulting from the loss of RAD51 paralogs or Brca2. This suggests that the 9-1-1 complex does not play a central role in translesion synthesis in this context. Despite reduced immunoglobulin gene conversion, the RAD9-/- and RAD17-/- cells do not exhibit a prominent defect in double-strand break-induced gene conversion or a sensitivity to camptothecin. This suggests that the roles of Rad9 and Rad17 may be confined to a subset of homologous recombination reactions initiated by replication-stalling lesions rather than those associated with double-strand break repair.

Original languageEnglish
Pages (from-to)6113-6122
Number of pages10
JournalMolecular and Cellular Biology
Issue number19
Publication statusPublished - Oct 2008
Externally publishedYes

ASJC Scopus subject areas

  • Molecular Biology
  • Cell Biology


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