Protein reconstitution in giant vesicles

Most mythologies explain the existence of different species on Earth, but none talk about the exact event that created life or what defines life. According to the French philosopher and mathematician Rene Descartes, the ability to think was the proof of existence or living. Austrian physicist Erwin Schrodinger also delved into a similar question and lectured about the definition of life and consciousness. These lectures were later published as a book called “What is Life?”. This book covered a lot of information about the physics and chemistry of the living. However, what still eludes our understanding is the first 'sign' of life that could sustain itself, propagate, and diversify. At the molecular level, many small molecules would have combined to become polymers like proteins and nucleic acids. This entire process would have occurred in a biological compartment, which might have developed into the modern-day cell membrane as we know it. There are efforts across the scientific community to answer such questions with many hypotheses about the sequence and the mechanism of events that created life. 

Bottom-up synthetic biology aims to create minimal cells by combining different modules, such as compartmentalization, growth, division, and cellular communication. All living cells have a membrane that separates them from the surrounding aqueous medium and helps to protect them. In addition, all eukaryotic cells have organelles that are enclosed by intracellular membranes. Each cellular membrane is primarily made of a lipid bilayer with membrane proteins. Lipids are amphiphilic molecules that assemble into molecular bilayers consisting of two leaflets. The hydrophobic chains of the lipids in the two leaflets face each other, and their hydrophilic headgroups face the aqueous surroundings. Giant unilamellar vesicles (GUVs) are model membrane systems that form large compartments with a size of many micrometers and enclosed by a single lipid bilayer. The size of GUVs is comparable to the size of cells, making them good membrane models which can be studied using an optical microscope. However, after the initial preparation, GUV membranes lack membrane proteins which have to be reconstituted into these membranes by subsequent preparation steps. Depending on the protein, it can be either attached via anchor lipids to one of the membrane leaflets or inserted into the lipid bilayer via its transmembrane domains.

During my PhD, I made these GUVs with synthetic lipids and attached proteins to it. I also developed a microfluidic device to quantify the membrane protein interactions. This device could also be used to image the morphological changes in GUVs caused by introducing molecular asymmetry across the bilayer. 

For more a detailed information about my work, feel free to download the published version from the University of Potsdam (click here).