After synthesis-dependent strand annealing (SDSA), the reannealed DNA molecule contains a single strand nick (SSB) in the newly synthesized strand, between the 3' end of the newly added stretch of nucleotides and the resected 5' end of the strand. In addition, the complementary strand contains a gap created by resection that was not filled during DNA repair synthesis. Additional DNA synthesis occurs to fill in this remaining single-strand gap present in the reannealed DNA duplex. SSBs between newly added stretches of nucleotides and resected 5' ends need to be closed by DNA ligases. The identity of DNA polymerase(s) and DNA ligase(s) involved in the completion of DNA double-strand break repair through SDSA is not known. RTEL1 DNA helicase, which resolves D-loops in SDSA, binds PCNA and may promote DNA synthesis after reannealing (Vannier et al. 2013). DNA polymerase alpha is implicated in late steps of DNA repair synthesis (Levy et al. 2009), but other PCNA-bound DNA polymerases may also be involved. LIG1, as well as LIG3 in complex with XRCC1, may act to ligate SSBs (Fan et al. 2004, Mortusewicz et al. 2006, Mortusewicz et al. 2007, Puebla-Osorio et al. 2006).
Mortusewicz, O, Leonhardt, H
Ding, H, Petalcorin, MI, Sandhu, S, Boulton, SJ, Wu, X, Vannier, JB, Nabi, Z
Zhu, C, Alt, FW, Puebla-Osorio, N, Lacey, DB
Otterlei, M, Wilson, DM, Fan, J, Wong, HK, Tomkinson, AE
Bresson, A, Maiorano, D, de Murcia, G, Van Dorsselaer, A, Oehlmann, M, Ménissier-de Murcia, J, Schreiber, V, Delalande, F, Nasheuer, HP, Lévy, N
Rothbauer, U, Mortusewicz, O, Leonhardt, H, Cardoso, MC
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