Submitted by Vanessa Bismuth on Fri, 19/05/2023 - 12:57
Scientists have now been able to demonstrate that we can exert control on lipid membranes and their phase behaviour using rationally designed “DNA line-actants”, which will help improve our understanding of membrane biophysics, and more broadly, the role that lipid phase separation plays in biological functionality.
The line-actants are important tools for the construction of “synthetic cells”, advanced biomimetic devices that imitate the features and functionalities of biological cells. Roger Rubio Sánchez
Previously, these properties of lipid membranes could only be controlled by natural protein machinery that cells have evolved over billions of years.
Recently, researchers have used model cell-like objects, or “synthetic cells”, to study and replicate responses observed in cell membranes that underpin important biological phenomena. To engineer functional synthetic membranes, they have used the tools of DNA nanotechnology to construct devices at the nano-scale (a billionth of a metre). In particular, they used a technique known as DNA origami, which allows to create nano-scaled shapes by “folding” long DNA strands with shorter DNA “staples”. In this study the researchers explore the use of DNA origami nano-devices to control lipid phase separation in synthetic membranes and how it can be exploited to construct synthetic cells with advanced functionalities.
“The DNA devices that we have introduced in our study behave in two dimensions, like soap molecules, which accumulate at a two-dimensional surface between three dimensional immiscible liquids, such as oil and water. These are referred to as surfactants,” said first and co-lead author Roger Rubio Sánchez, who conducted this research during his PhD at the Cavendish Laboratory and is now based at the Department of Chemical Engineering and Biotechnology, University of Cambridge. “In turn, our devices accumulate at the one-dimensional “line interface” between two dimensional co-existing liquids in the membranes and are then called “line-actants”.
“Just like soap helps stabilising small oil droplets in water, we are showing that the DNA-origami line-actants help the formation of small lipid domains on the surface of membranes.”
While some naturally occurring proteins and inorganic nanoparticles have been shown to behave as membrane line-actants, this is the very first time that line-actants have been rationally engineered completely from the “bottom-up”.
Recently published in the Journal of the American Chemical Society, their study in collaboration with Prof. Pietro Cicuta (Cavendish Laboratory) and Dr. Bortolo Mognetti (Université Libre de Bruxelles) demonstrates the ability of the nano-devices to accumulate at the line interface. This emerges from the affinity that various hydrophobic molecules have for different lipid domains. By strategically arranging the molecules as membrane anchors onto a DNA origami plate, the researchers could assemble the line-actants. Their ability for line-accumulation depends on the chemical nature and positioning of the anchors, giving them full freedom in designing the properties of the line-actants, including their de-activation, which is unprecedented. De-activation induces re-organisation of the lipid domains and, under the right conditions, can produce splitting of lipid membranes into two cell-sized objects. This is a particularly exciting result as it replicates in synthetic systems membrane fission, a key biological response involved in cell division, internalisation, and trafficking.
“The origami line-actants represent an elegant demonstration of how nanoscale engineering can be combined with simple biophysical principles”, said lead author Lorenzo Di Michele, formerly from the Cavendish Laboratory and now at the Department of Chemical Engineering and Biotechnology. “This way, we can control a complex emergent response such as membrane phase separation.”
“The DNA line-actants allow us to tackle research challenges that range from better understanding cellular life to engineering sophisticated and applicable synthetic cells”, said Rubio Sánchez “The line-actants are important tools for the construction of “synthetic cells”, advanced biomimetic devices that imitate the features and functionalities of biological cells. Specifically, the line-actants will help in establishing advanced and elusive functionalities such as synthetic cell division, trafficking, and signalling.”.
Continuing to expand on the functionality of the DNA line-actants, the researchers are now applying them in (bio)membrane engineering, which is allowing them to better understand the biological membrane functionality, and to develop more advanced and applicable synthetic cell technologies. In the future, these functionalities may help unlock applications of synthetic cells to therapeutics and diagnostics.
Reference:
Roger Rubio-Sánchez, Bortolo Matteo Mognetti, Pietro Cicuta, and Lorenzo Di Michele. ‘DNA-Origami Line-Actants Control Domain Organization and Fission in Synthetic Membranes.’ Journal of the American Chemical Society (2023) DOI: 10.1021/jacs.3c01493
Image:
Coloured 3D view of the study's DNA origami plate - Credit: Roger Rubio Sánchez