PhD Student
Associate member of the GRK2516
Group: Prof. Andreas Walther, JGU Chemistry
Contact: E-mail, Web

Research Project: Experiments
Transient Liquid Liquid Phase Separation under Compartmentalization

Living cells have attracted the interest of researchers because of their ability to perform numerous life-determining functions, such as cell growth, adhesion, morphogenesis, division, self-protection, and the establishment of intercellular communication through metabolic reactions that cause the downstream physicochemical change of their internal biomacromolecules (nucleic acid, proteins, etc.) in a trapped state. One of the grand challenges of systems chemistry is to emulate some of the above functions in artificial microcompartments, using synthetic building blocks in a bottom-up approach to understand how biochemical transformations establish the structure–function relationship.
Conventional chemistry deals with reactants that lead to stable molecules following a classical equilibration pathway. This is fundamentally different from the far-from-equilibrium fashion in which living systems work. This can be replicated employing a suitable ‘fuel’ which drives a system to a high energy state and coupling it with a destabilizing environment which can bring the system back to the original state. Keys to non-equilibrium behaviour are the mechanisms through which systems are able to extract energy from the chemical reactants (‘fuel’) that drive such processes. When they are coupled to another dynamic process, they form a chemical engine that powers function by transducing chemical energy into other forms.
Recently our group has developed an ATP-driven enzyme regulated reaction network (ERN) consisting of concurrent ligation and restriction pathways (namely T4 ligase and BsaI enzymes in our case), which gives rise to a non-equilibrium steady-state. The lifetimes of the transient steady states depend on the ATP (fuel) concentration, whereas the steady state dynamics, e.g., exchange frequencies of subunits, are given by the ratio of the enzymes. This system allows us to generate a non-equilibrium state and enables us to study the transient formation of three elementary units of cells: DNA polymers, coacervates as mimics for liquid-liquid phase separated organelles, and DNTs as cytoskeleton mimics. It is our objective now to synthesize these bodies inside liposomes and understand how physical interactions and energetics need to be tuned to regulate the dynamics of the emergent processes. Currently we are focusing on liquid-liquid phase separation (LLPS) that has been established in our group inside a microenvironment. This will allow us to monitor the formation of coacervates subjected to a destabilized atmosphere (away from equilibrium) inside a protocell (liposome).

Fig. 1 a) Schematic representation of the ATP driven reaction network comprising of concurrent ligation and restriction pathways. b) Comparing classical coacervation processes under thermodynamic equilibrium with our strategy to make unstable polymers giving rise to energetically up-hill coacervates. c) The overall plan: making unstable all DNA coacervates (green droplets in the inset) inside liposomes (images acquired using confocal microscopy).