Replication stress by MMS stimulates DNA synthesis in post-replicative G2-phase in S. pombe

DNA replication is generally limited to S-phase but replication stress can drive cells to undergo DNA synthesis outside of S-phase. Mitotic DNA synthesis pathway is known to be activated to deal with replication stress-induced chromosomal instability. There is also growing evidence that residual DNA synthesis can occur in G2. We demonstrate that fission yeast cells stimulate DNA synthesis in G2-phase but not in M-phase in response to DNA alkylating agent MMS. Auxin-induced degradation of DNA replication helicase Mcm4 during G2, but not during mitosis, inhibits post-replicative DNA synthesis.