This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: Researchers have captured the moment two DNA molecules zip together, overcoming their identical negative charges to pair up and revealing a mechanism that has puzzled scientists for more than 20 years. Using high-powered atomic force microscopy, scientists at the University of Sheffield and the University of York directly imaged two DNA double helices locking together, marking the first time this fundamental biological process has been visualized.
Like charges normally repel one another, yet DNA molecules must pair up inside living cells to carry out essential biological processes. This pairing plays a crucial role in genetic recombination, gene silencing, chromosome packaging and cancer development. The researchers observed short DNA fragments matching up with exact precision, groove for groove.
Advanced computer simulations revealed that positively charged metal ions, including nickel, magnesium and calcium, act as tiny molecular bridges, nestling inside the grooves to lock the two strands together. The work is published in the journal Nucleic Acids Research. Thomas Catley, co-lead author from the School of Chemical Materials and Biological Engineering at the University of Sheffield, said, "To be able to directly visualize this long-hypothesized mechanism for the first time was incredible.
The advanced imaging techniques at our disposal have allowed us to uncover these key DNA interactions, which have implications for many cellular processes. It opens the door to studying other DNA interactions that, until now, have existed only as theory. "Hopefully, these programmable interactions could eventually help engineers design custom DNA structures for future biotechnology, such as DNA origami, and shed light on how DNA is actually packaged inside cells." Professor Agnes Noy, from the School of Physics, Engineering and Technology at the University of York, who co-led the research, said, "This discovery could help researchers identify regions of the genome specifically involved in DNA pairing.
These regions may become particularly important when mutations disrupt normal cellular processes and contribute to cancer." The findings confirm a theory dating back more than two decades known as the "DNA zipper" model, originally proposed by Professor Alexey Kornyshev from Imperial College London and his collaborators. The model suggested that surrounding salt ions create alternating charge patterns, allowing DNA molecules to line up like interlocking spiral staircases. To test this, the team used atomic force microscopy to scan DNA samples and build topographical maps.
At the same time, detailed computer models tracked the movement of individual atoms and ions. They discovered that double-charged metal ions act like two charged arms, holding both DNA strands simultaneously across the gap. Victor Velasco-Berrelleza, first author from the University of Sheffield's School of Mathematical and Physical Sciences, who led the computer simulations and analysis, added, "While microscopy can show us what happens, it's the simulations that allow us to uncover the molecular mechanism behind it.
Extract — continue reading at the source.
