When DNA becomes its own enemy: How DNA impacts replication dynamics, fidelity, and integrity

Every dividing cell in our body accomplishes a remarkable feat – copying an entire genome without a single mutation on average. Perturbations of genome replication, collectively termed replication stress, can result in mutations and genomic instability. Sequences that can adopt unusual DNA secondary structures are implicated as a source of replication stress and are hotspots for mutations and translocations across a variety of cancer types. However, repetitive and structure-forming sequences also play important biological and regulatory roles, and mechanisms must be in place to preserve them. The causal relationship between perturbed replication dynamics, altered fidelity and loss of genome integrity is unclear. We have recently discovered that structure-forming sequences stall reconstituted budding yeast replisomes, establishing the DNA template itself as a direct source of endogenous replication stress. Our ultimate aim is to define how human replisomes, in vitro and in cells, respond to challenging DNA sequences. Through a bold research program we will develop state-of-the-art molecular approaches and novel cellular models to address the following specific questions: 1. How does the DNA template affect replication dynamics? 2. How is replication fidelity affected by repetitive DNA and sequence context? 3. What mechanisms preserve genome integrity within challenging sequences?