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DNA carries a negative charge, which might suggest that DNA molecules should repel each other due to the like charges. However, within living cells, DNA must occasionally come into close proximity in order to recognize matching sequences. These interactions are crucial for genetic recombination, gene silencing, and potentially have implications in cancer development.
Recent research utilizing a powerful atomic force microscope has provided insights into how DNA molecules align with remarkable precision, matching groove by groove. It has been revealed through computer simulations that this close contact is facilitated by positively charged metal ions acting as molecular bridges between the DNA molecules.
Overcoming DNA Repulsion with Small Ions
Professor Agnes Noy from York University’s School of Physics, Engineering, and Technology, co-leading the research, stated, “This groundbreaking discovery could aid in identifying critical genomic regions involved in DNA pairing, especially when mutations disrupt normal cellular processes leading to cancer.”
The findings provide experimental support for the “DNA zipper” model proposed about two decades ago. The model, conceived by Professor Alexei Kornyshev of Imperial College London and colleagues, suggests that salt ions surrounding DNA could create alternating charge patterns that help align adjacent DNA molecules like interlocking spiral staircases.
Although the proposed mechanism has been difficult to directly observe, researchers are exploring the process using atomic force microscopy to map DNA molecule surfaces at a small scale. Further, computer simulations track atomic and ionic movements through DNA, providing insights into DNA pairing and molecular forces.
The research reveals that certain DNA sequences form stronger contacts than others, with specific hotspots where two helices are more likely to align. Understanding these interactions could help pinpoint genome regions crucial for DNA recognition and pairing, important in cases where mutations lead to cancer.
Additionally, the discovery opens doors for potential applications beyond medicine, as certain DNA sequences can be engineered to interact more strongly, potentially aiding in the development of customized DNA structures for biotechnology purposes.
The study titled “Imaging and mechanism of DNA-DNA recognition by divalent ions” has been published in the journal Nucleic acid research.
Source: www.sciencedaily.com
