Controlling liquid-liquid phase separation of nucleic acid motifs via programmable biochemical reactions

The toolkit of DNA nanotechnology has recently provided a framework to design and build motifs for liquid-liquid phase separation (LLPS). Using DNA nanotechnology we are exploring the mechanisms and design rules by which condensates can be controlled through chemical reactions. We focus on multivalent, star-shaped DNA motifs whose interactions can be designed by engineering  single stranded domains (sticky ends).  I will describe, by theory and experiment, how modification of the structure of DNA nanostars affects their macroscopic condensation kinetics. By changing the various domains of the DNA monomer we achieve a predictable growth profile of the condensates. Further, we obtain reversible dynamic control of condensate formation and dissolution by utilizing DNA strand displacement reactions that deactivate or reactivate the DNA monomer interaction domains. By changing DNA monomer design and sequence makeup, we explore the tunability of these reactions under different conditions. Our approach may be useful to build synthetic membraneless organelles whose formation can be temporally controlled via chemical reactions.