Franziska Bleichert

Molecular mechanisms of DNA replication and chromosome maintenance

Cellular life depends on the faithful propagation of genetic information. Prior to cell division, a host of different proteins work in concert to duplicate genomes by semi-conservative replication in a manner that preserves relative gene copy numbers and allows for the segregation of copied chromosomes into daughter cells.

To sustain genome integrity, DNA replication must be highly efficient and accurate, with approximately two light years? worth of DNA synthesized during the lifespan of a human being and an error rate of less than 1 per 100 million incorporated bases. This robustness is remarkable considering that the DNA substrate for the replication machinery is packaged into chromatin within the crowded nuclear environment of eukaryotic cells, and it necessitates that DNA replication is temporally and spatially tightly coupled to chromatin remodeling events. How chromatin environment controls key DNA replication events, however, remains poorly understood.

Our research program is focused on uncovering molecular mechanisms by which the nuclear chromatin landscape impacts different steps of DNA replication. We use an integrated mix of biochemical, biophysical, and structural methods (single-particle cryo-electron microscopy and X-ray crystallography) to identify and visualize key chromatin-associated replication intermediates at atomic or near-atomic resolution. In combination with in vivo genetic approaches, our efforts will help not only to establish molecular models for how the likely complex interplay between chromatin structure and DNA replication contributes to maintaining chromosome copy number and genome stability, but also to generate mechanistic frameworks for how deregulation of these events contributes to human disease.

Franziska Bleichert
Gabi Gruber
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