DNA phase-separation as a general mean of regulating gene expression in hybrid cells.

Liquid-liquid phase separation is increasingly recognised as a key mechanism to regulate gene expression in living cells by controlling the accessibility of genetic material and its co-localisation with transcription machinery.

Although mechanisms that trigger phase separation in biological cells are not fully understood, a similar control of transcriptional activation could be recapitulated in hybrid cells, engineered from the bottom-up by combining biological and man-made components. Programming the condensation of genetic material (DNA) and its co-localisation with cellular machinery is a particularly promising approach to regulate transcription. DNA aggregation can be induced by well-understood canonical and non-canonical secondary structures, and its occurrence can thus be controlled by a variety of physical stimuli, including temperature, crowding agents and exposure to certain ions.

Herein, we propose to generate a hybrid cell system that can be transcriptionally activated by triggering nucleic-acid phase separation, offering an orthogonal solution to current methods that fully rely on small-molecule treatment (e.g. IPTG) and cannot be controlled easily by physical means. Besides offering an alternative method to regulate gene-expression in artificial cells, this project will yield insights on the fundamental physical processes that might be responsible of gene-regulation via liquid-liquid phase separation in living cells.