UNIST, World's First Real-Time Observation of Phenomena Occurring During DNA Replication

A technology that can visualize DNA replication in real time has been developed. It is expected to contribute to the treatment of various diseases by solving problems related to DNA replication.

The research team led by Professor Ja-il Lee from the Department of Life Sciences at UNIST used the ‘DNA curtain’ technology, which visually images single molecules, to perform real-time imaging of the DNA replication process.

For the first time in the world, they directly observed DNA replication and collisions with R-loops or transcription proteins, revealing the secrets of the long-standing molecular biology challenges of ‘replication-transcription’ and ‘replication-R-loop’ collisions.

DNA replication is a crucial process that transmits genetic information to the next generation. However, the process can be halted due to collisions with R-loops generated by incomplete transcription or the transcription process itself, which reads genetic information contained in DNA and converts it into RNA.

This phenomenon is called ‘DNA replication stress.’ DNA replication stress is a cause of various diseases such as cancer, neurological disorders, and aging. Therefore, understanding replication-transcription and replication-R-loop collisions is necessary to prevent or treat diseases.

The research team utilized the single-molecule imaging technology called ‘DNA curtain.’ They performed real-time imaging of the DNA replication process by Phi29 DNA polymerase, a bacterial virus widely used in advanced biotechnology, and observed collisions with transcription and R-loops.

They experimentally proved that a single R-loop can stop DNA replication and induce DNA replication stress, and also confirmed that removing RNA necessary for protein synthesis from the R-loop allows the halted replication to resume, thereby relieving replication stress.

Image of DNA replication and Alu element collision using a DNA curtain.

The team also observed collisions with R-loops generated at telomeres, the ends of chromosomes. Telomeres are known to shorten with repeated DNA replication and are closely related to the lifespan and aging of organisms.

They confirmed that G-quadruplex structures formed in human telomeres cause DNA replication to stop more frequently at R-loops.

Additionally, the team observed replication-transcription collisions, confirming that DNA replication stops at an even higher frequency when colliding with R-loops in this case.

Professor Ja-il Lee of the Department of Life Sciences explained, “DNA replication is the foundation of life phenomena, and this study is the world’s first to perform real-time fluorescence imaging of collisions between DNA replication, transcription, and R-loops.”

He added, “It seems that our direct answer to the long-standing molecular biology problem of ‘replication-transcription collisions’ has been recognized. We hope to apply this technology to research on human DNA replication and transcription in the future.”

PhD candidate Soobin Kim, the first author, said, “R-loops are currently being actively studied worldwide as causes of various diseases such as leukemia, cancer, and neurological disorders, and this research is expected to contribute to the treatment of diseases caused by R-loops.”

This study, related to nucleic acids such as DNA and RNA, was published online on November 22 in the prestigious international journal Nucleic Acids Research.

The research was supported by the Samsung Future Technology Development Foundation project and the Basic Science Research Laboratory support project promoted by the National Research Foundation of Korea under the Ministry of Science and ICT.

This content was produced with the assistance of AI translation services.