DNA is incessantly exposed to UV light from the sun, a form of electromagnetic radiation capable of inducing chemical alterations that can lead to mutations, and thereby raise the risk of cancerous growths. Despite this relentless assault, DNA exhibits remarkable photostability—the capacity to rapidly dissipate absorbed UV energy and revert to a stable, damage-free state before any mutagenic processes can take hold. The molecular mechanisms orchestrating this impressive resilience, however, have remained largely elusive until now.

The collaborative research effort, which combined expertise from the University of Surrey alongside Aix Marseille University, the French National Centre for Scientific Research (CNRS), and Université Claude Bernard Lyon 1, employed advanced quantum chemical simulations to probe these phenomena. By modeling DNA’s behaviour at the atomic scale and in real time, the team succeeded in visualizing the precise sequence of events that occur after DNA absorbs UV photons, particularly focusing on guanine-cytosine base pairs. These base pairs are critical components of DNA’s double helix structure and thus serve as a vital window into understanding the molecular underpinnings of DNA’s inherent photoprotection.

Harnessing state-of-the-art computational techniques, the researchers discovered that following UV excitation, DNA channels the excess energy through a sophisticated series of molecular pathways that involve the concerted transfer of electrons and protons. These transfers occur almost instantaneously—on the timescale of femtoseconds, or quadrillionths of a second—neutralizing the potentially harmful excited states and safely restoring DNA to its ground state. This rapid energy dissipation prevents the formation of photolesions that could otherwise compromise genomic integrity.

Importantly, the study reveals that DNA does not rely on a singular escape route for energy deactivation. Instead, it accesses a rich and competing network of ultrafast relaxation mechanisms. These pathways are characterized by a dynamic interplay between electron movement and proton transfer, which, while closely correlated, are not rigidly coupled. Such flexibility appears to underlie the robustness of DNA’s photoprotection, enabling multiple parallel avenues for energy release that collectively enhance resilience to UV-induced damage.

Dr. Marco Sacchi, Associate Professor of Physical and Computational Chemistry at the University of Surrey and the lead senior author of this research, emphasized the evolutionary significance of these findings. He remarked that DNA’s enduring resilience under constant UV exposure is a tribute to nature’s sophisticated biochemical infrastructure that has evolved over billions of years. The visualization of these ultrafast molecular processes provides unprecedented insight into how DNA preemptively counters photodamage, effectively nipping mutagenic events in the bud.

The lead author, Juliana Gonçalves de Abrantes, a postgraduate researcher at the University of Surrey, highlighted the remarkable diversity and complexity of these relaxation pathways. She explained that the strong yet flexible coupling between electron and proton dynamics results in a multitude of decay channels, thereby providing redundancy and enhancing the reliability of DNA’s protective mechanisms. This multiplicity ensures that even if one pathway is compromised, others can step in to dissipate the energy harmlessly.

These insights carry profound implications beyond basic molecular biology. By better understanding how DNA shields itself from radiation-induced harm, scientists could improve current models of mutation, ageing, and carcinogenesis, potentially informing the development of novel therapeutic interventions. Moreover, these revelations bear weight in the biotechnology field, where UV stability of nucleic acids is a factor in various applications, and could also influence the search for life’s origins and adaptation strategies in astrobiology.

The methodology utilized in the study—high-level quantum chemistry simulations combined with atomic-scale real-time monitoring—sets a new standard for probing biomolecular photophysics. It allows scientists to capture fleeting intermediate states that are otherwise experimentally inaccessible, rendering an intricate atomic ballet visible and measurable. Such techniques promise to deepen our understanding of other photoprotective systems and could spur innovation in designing artificial materials with enhanced UV resilience.

Historically, the photostability of DNA was attributed either to single, dominant relaxation pathways or to relatively simple deactivation mechanisms. This study challenges those earlier notions by unveiling a far richer landscape of molecular processes that work in concert. It attests to the notion that biological systems often employ redundancy and complexity as evolutionary safeguards against environmental chaos.

In conclusion, this pioneering research decisively illustrates that the molecular survival of DNA under solar radiation is governed by a multifaceted network of ultrafast relaxation events that involve a nuanced synergy between electron shifts and proton dynamics. This elegant and elaborate natural design secures the integrity of genetic information, maintaining cellular health and viability in a UV-rich environment—a testament to the resilience and adaptability of life at the molecular frontier.

Subject of Research: Molecular mechanisms of DNA photostability focusing on charge and proton transfer in cytosine–guanine base pairs

Article Title: The Hidden Routes of DNA Photostability: Charge and Proton Transfer in Excited Cytosine–Guanine Tetramers

News Publication Date: 7-May-2026

Web References:
https://pubs.acs.org/doi/10.1021/acs.jpclett.6c00376
http://dx.doi.org/10.5281/zenodo.18456089

Keywords

DNA photostability, ultraviolet radiation, molecular dynamics, charge transfer, proton transfer, quantum chemistry simulations, guanine-cytosine base pairs, photoprotection mechanisms, femtosecond reactions, mutation prevention, DNA resilience, biophysics

As human cells continuously divide, they inevitably sustain DNA damage, posing a significant risk for developing cancer. The BRCA2 gene is integral to a crucial DNA repair mechanism known as homology-directed repair. This process is essential for maintaining genomic stability, yet mutations in BRCA2 can diminish its ability to repair DNA, thereby heightening cancer risk. This unfortunate outcome often leads cells to become heavily reliant on alternative DNA repair pathways, particularly the one involving PARP1—a phenomenon exploited by PARP inhibitors designed to disrupt this backup pathway.

The recent findings, published in the prestigious journal Nature, reveal an unexpected and vital role of BRCA2 in modulating the actions of PARP1 at sites of DNA damage. The research demonstrates that the efficacy of PARP inhibitors is closely tied to the functional state of BRCA2 in cancer cells. Cancer cells with intact BRCA2 are more likely to respond favorably to PARP inhibitors, underscoring the need for understanding the intricate dynamics between these molecular players.

Due to the challenge of accurately estimating the proportion of cancer cells with functional BRCA2, understanding its role remains essential. Previous studies suggest that a subset of cancer cases—15-20% of ovarian cancers, 6-8% of breast cancers, 8-10% of prostate cancers, and 8-10% of pancreatic cancers—exhibit either inherited mutations in BRCA2 or new mutations occurring during tumor evolution. This information is critical in framing the therapeutic landscape for patients relying on PARP inhibitors for treatment.

The senior author of the study, Eli Rothenberg, Ph.D., emphasizes the collaborative efforts between molecular discovery and clinical advancements, indicating that their work aims to connect insights from BRCA2 and related pathways to practical applications in diagnostics and treatment. The aim is to facilitate a paradigm shift in cancer therapy through patient-specific strategies tailored to the unique genetic makeup of each tumor.

To explore the complex interactions between BRCA2 and PARP1, the research team employed advanced imaging techniques pioneered at NYU Langone. Dr. Rothenberg noted that these innovative imaging tools provided real-time visualization of how BRCA2 operates to protect DNA repair complexes in living human cells. This understanding can bring scientists closer to the dream of creating individualized therapies that offer enhanced efficacy against cancer.

The study revealed that BRCA2 acts as a molecular shield in cells, preventing PARP1 from lingering at sites of DNA damage where it would typically bind and interfere with the DNA repair process. By allowing RAD51, a critical protein for accurate DNA repair, access to damaged DNA, BRCA2 plays a protective role against treatment-induced DNA breaks that can cause harm to cancer cells. In effect, BRCA2 appears to dictate the fate of cancer cells when exposed to PARP inhibitors.

The contrast was stark in cancer cells with defective BRCA2, where PARP1 could overpower the process, blocking RAD51 from performing its essential repair function. This blockade leads to an accumulation of DNA damage, making BRCA2-deficient cells particularly vulnerable to PARP inhibitors. This relationship elucidates why patients whose tumors exhibit compromised BRCA2 are generally more susceptible to these therapies, presenting opportunities for practitioners to leverage such biomarkers in treatment decisions.

Clinical implications of this discovery are profound. The variability in BRCA2 functionality across different tumors underscores the importance of personalized cancer treatment strategies. Study author Sudipta Lahiri, Ph.D., who composed the experimental design, anticipates this research will initiate a dialogue about patient-specific tumor profiling. Such profiling could guide clinicians in selecting the most effective therapies based on the unique molecular landscape of each patient’s cancer.

The commitment of the team at NYU Langone to advancing our understanding of BRCA pathways is evidenced by their ongoing efforts to dissect the structural components of BRCA2. By identifying the specific domains involved in its protective effect against PARP1, researchers aim to develop innovative therapies capable of overcoming resistance to current treatments, thus expanding the arsenal available to oncologists.

The study involved a multidisciplinary team, including esteemed colleagues from the Department of Biochemistry and Molecular Pharmacology at NYU Grossman School of Medicine and collaborators from Yale University’s Department of Therapeutic Radiology. Their combined expertise underlines the importance of collaborative scientific endeavors in producing meaningful advancements in cancer research.

This research, funded by multiple National Institutes of Health grants and supported by charitable foundations, spotlights the ongoing efforts to translate molecular discoveries into tangible therapeutic strategies. As the understanding of cancer biology evolves, there remains hope that these insights will usher in an era of more effective, personalized treatments tailored to individual patient profiles.

In summary, this pivotal research sheds light on the crucial role played by BRCA2 in regulating PARP1 and subsequently influencing the efficacy of PARP inhibitors in cancer therapy. As researchers continue to explore the nuanced interactions in this molecular landscape, the quest to harness this knowledge for improved patient outcomes represents a significant stride toward more sophisticated cancer treatment modalities.

Subject of Research: Cells
Article Title: BRCA2 prevents PARPi-mediated PARP1 retention to protect RAD51 filaments
News Publication Date: 26-Feb-2025
Web References: https://www.nature.com/articles/s41586-025-08749-x
References: None
Image Credits: None
Keywords: Cancer therapy, Molecular biology, DNA repair, BRCA2, PARP inhibitors, Precision medicine, Oncology, Personalized treatment