Molecular Mechanisms of DNA Replication and Genome Stability

The molecular choreography of DNA replication is a finely balanced process ensuring that genetic information is faithfully transmitted during cell division. Replication initiation begins with origin licensing, where a pre-replication complex assembles on specific genome loci and recruits the heterohexameric MCM helicase. Activation of this helicase unwinds the double helix, generating replication forks at which polymerases synthesise new strands. Leading-strand synthesis is continuous, whereas lagging-strand synthesis is discontinuous, producing Okazaki fragments that are matured by polymerase and ligase activities. Coordinated progression of the replisome is essential to prevent collisions with transcriptional machinery and to resolve complex DNA secondary structures. The cell employs an array of surveillance mechanisms—collectively termed the DNA damage response—to detect replication stress, defined as impediments to fork progression, and to stabilise stalled forks. Homologous recombination repairs collapsed forks and double-strand breaks, preserving genome integrity. Additional layers of control, including ubiquitin-mediated signalling and specialised checkpoint pathways such as ATR–CHK1, modulate replisome components in response to genotoxic insults. Fidelity in replication and efficient resolution of DNA lesions underpin genome stability, thereby safeguarding against mutagenesis, chromosomal aberrations and disease onset.

Research from Nature Portfolio

Recent studies have elucidated critical factors that operate during S-phase to maintain fork integrity and genome stability. One investigation revealed that an E3 ubiquitin ligase prevents DNA damage at sites where replication forks encounter transcription machinery. Rapid depletion of this ligase in S-phase leads to fork collapse, cell cycle arrest and senescence, highlighting its role in resolving replication–transcription conflicts. Another body of work has demonstrated that cancer cells upregulate replication fork protection mediators independently of checkpoint activation. Elevated levels of these proteins support fork progression under oncogene-induced stress, enabling tumour cells to tolerate replication challenges and sustain proliferation. Furthermore, foundational research on a helicase–nuclease complex has shown that it facilitates the nucleolytic processing of double-strand break ends by the MRN complex during homologous recombination, promoting effective repair and accurate chromosome segregation.

Molecular Mechanisms of DNA Replication and Genome Stability publication trend

The graph below shows the total number of articles in molecular mechanisms of dna replication and genome stability across all publications each year (not limited to Nature Index journals).

Technical terms

Replication fork: The Y-shaped region where parental DNA strands are separated and newly synthesised strands are formed.

Replisome: The multiprotein complex that carries out DNA unwinding and synthesis during replication.

Replication stress: Any obstacle or perturbation that impedes the progression of replication forks, potentially leading to DNA damage.

Homologous recombination: A high-fidelity repair pathway that uses a sister chromatid as a template to mend double-strand breaks and restart stalled forks.

E3 ubiquitin ligase: An enzyme that catalyses the transfer of ubiquitin to target proteins, regulating their stability or activity.

Chromatin bridge: A DNA connection between segregating daughter nuclei arising from unresolved replication or recombination intermediates.

cGAS-STING pathway: An innate immune signalling cascade activated by cytosolic DNA, leading to interferon production.

References

1. TRAIP resolves DNA replication-transcription conflicts during the S-phase of unperturbed cells. Nature Communications (2023).
2. Human Endonuclease ANKLE1 Localizes at the Midbody and Processes Chromatin Bridges to Prevent DNA Damage and cGAS‐STING Activation. Advanced Science (2023).
3. Overexpression of Claspin and Timeless protects cancer cells from replication stress in a checkpoint-independent manner. Nature Communications (2019).
4. MCM8-9 complex promotes resection of double-strand break ends by MRE11-RAD50-NBS1 complex. Nature Communications (2015).
5. Preserving replication fork integrity and competence via the homologous recombination pathway. DNA Repair (2018).