Observing an isolated DNA molecule, while applying stretching or twisting forces on it, can provide valuable information to the scientific community. A study, published in the journal Nanoscale, details an effective technique to manipulate very precisely a DNA chain and, simultaneously, observing with great resolution what is happening along the molecule, for example, when interacting with proteins.
The work, carried out by researchers of the National Center of Biotechnology of the Superior Council of Scientific Research (CNB-CSIC), Spain, in collaboration with the University of Bristol, United Kingdom, combines two last-generation techniques used in molecular biology and biophysics. One of them, called ‘magnetic clamps’ allows stretching in a very controlled way the DNA. The second, a type of fluorescence microscopy called ‘TIRF’ (total interior reflection fluorescence microscope), allows observing the molecules with high resolution.
“We have managed to take technology one step further: until now we applied forces on DNA and we were able to detect changes in the extension of the molecule, but we could not visualize the cause of those changes“, explains Fernando Moreno-Herrero, researcher of the CNB-CSIC and director of this investigation.
“With this work we provide the scientific community with new tools to apply accurate forces to stretch a DNA molecule; and, at the same time, visualize what proteins bind to it or what processes are taking place,” says Julene Madariaga-Marcos, main author of this work and researcher of the CNB-CSIC. “The equipment and technology that we have in our laboratory to do this type of research is unique in Spain.”
Similar methods that combine manipulation and visualization tools have allowed seeing the DNA while disassembling a virus or to seeing in action proteins that repair the genetic material. In this work, the researchers demonstrate the utility of combining the magnetic clamps and TIRF microscopy to visualize how the ParB protein – implied in the segregation and condensation of the bacterial chromosome – joins the bacterium’s DNA.