DNA sequences that modify their structure depending on the environment

70 years ago, James Watson and Francis Crick discovered the classic DNA double helix, key to understanding how our genetic information is stored and transmitted. However, much remains to be known about the structure of DNA, especially in relation to the flexible regions, capable of adopting various forms depending on their environment. Now, some scientists have described the curious case of a DNA sequence capable of changing its shape with pH.

The discovery was made by a team from the Institute of Marine Sciences (ICM), the Barcelona Institute for Biomedical Research (IRB), the University of Barcelona and the Rocasolano Institute of Physical Chemistry (IQFR), in Spain.

This study assumes an approximation to the family of structures known as i-DNA, very different from the Watson and Crick double helix. “This family seems to be formed temporarily at certain times of the cell cycle, but its function is still not clear and it is the subject of much interest”, highlights Carlos González, a researcher at the IQFR who has participated in the research.

To date, the main characteristics of i-DNA known are its location near the promoter regions of many human genes and its stability in acidic environments. In fact, “until recently it was not known that it can also be formed under physiological pH conditions,” adds González. However, the researchers have not only shown that it can form under these conditions, but that it can also adapt its structure to do so. This change in shape could act as a control mechanism to modulate gene expression, according to the study authors.

Structure of an i-DNA that can change its shape according to the acidity of the environment. (Image: IQFR)

The work represents an important advance in the compression of DNA, which is not only the molecule responsible for storing and transmitting genetic information, but is also an essential molecule for near-future technologies linked to nanotechnology. “Molecules capable of changing shape in a controlled manner are a treasure trove for designing technological devices, such as sensors, motors, etc., at nanometer scales”, points out the IQFR researcher.

The study is titled “pH-Dependent Capping Interactions Induces Large-Scale Structural Transitions in i‑Motifs”. And it has been published in the academic journal The Journal of the American Chemical Society. (Source: Alejandro Parrilla García / CSIC)