Xenopus laevis egg extracts recapitulate complex genome maintenance processes that have not been reconstituted with purified components.  Using this approach, we have discovered new DNA replication and repair mechanisms that are defective in cancer. Click on an area of study to learn more.

Replication Termination

Single molecule movie of CMGs converging and being unloaded from DNA

When replisomes from adjacent origins of replication converge, DNA synthesis must be completed and the replication machinery unloaded. By colliding replication forks with a lac repressor array and then releasing the array with IPTG, we have elucidated the molecular events underlying replication termination.

Selected Publications

Vrtis et al (2021). Single-strand DNA breaks cause replisome disassembly. Molecular Cell 81, 1309-1318.

Low  et al. (2020). The replication fork suppresses CMG unloading from chromatin before termination. Genes&Development 34, 1534-45.

Deng et al. (2019). Mitotic CDK promotes replisome disassembly, fork breakage, and complex DNA rearrangements. Molecular Cell 73, 915-929.

Dewar et al. (2015). The mechanism of DNA replication termination in vertebrates.  Nature 525, 345-350.

Transcription-Coupled Repair

Preparation of nucleoplasmic egg extract

RNA polymerases frequently collide with replisomes and DNA damage, but how these conflicts are resolved remains mysterious. We have succeeded in activating transcription in egg extracts (T. Mevissen, unpublished results), and we are interested in recapitulating transcription-coupled DNA repair in this system.