Comparative genome-wide analyses reveal that DNA replication origins fire near the initiation site of highly transcribed genes, ensuring co-directional replication and transcription in highly active regions of the human genome.

Eukaryotic origin firing depends on assembly of the Cdc45-MCM-GINS (CMG) helicase, which requires the leading-strand polymerase Pol ɛ. Here the authors present a structural analysis of a CMG Pol ɛ on a DNA fork, providing insight on the steps leading productive helicase engagement to the DNA junction.

This protocol describes high-throughput sequencing strategies for mapping early-firing replication origins and fork movement. Both procedures rely on EdU labeling of nascent DNA and the use of hydroxyurea to limit fork progression in synchronized cells.

RepID has previously been shown to promote origin firing. Here the authors reveal that RepID regulates replication origins via the recruitment of the CRL4 complex, and prevents re-initiation and unscheduled DNA replication.

In vitro experiments, using purified proteins and an assay that detects DNA unwinding, reveal the mechanism of activation of eukaryotic DNA replication.

The Greatwall/Ensa/PP2A-B55 pathway controls mitotic substrate phosphorylation and mitotic entry. Here the authors show that cells regulate S phase duration by controlling the ubiquitin-proteasome degradation of Treslin in a Gwl/Ensa-dependent pathway.