(A) RFs slow and then stall during HU treatment, generating ssDNA. (B) This ssDNA is a signal that resembles DNA damage from resected DNA DSBs or single-strand repair patches. (C) ssDNA is also ...

When the RF stalls, the initial ssDNA signal activates ATR. Once activated, ATR kinase phosphorylates a variety of proteins to induce the replication checkpoint and promote RF stability.

These stalled forks are a major source of genome instability. The encounter of replisomes with damage in the leading- and lagging-strand templates have different consequences. As long as unwinding by ...