Liquid Crystal Coacervates Composed of Short Double-Stranded DNA and Cationic Peptides

Abstract

Phase separation of nucleic acids and proteins is a ubiquitous phenomenon regulating sub-cellular compartment structure and function. While complex coacervation of flexible single stranded nucleic acids is broadly investigated, coacervation of double stranded DNA (dsDNA) is less studied because of its propensity to generate solid precipitates. Here, we reverse this perspective by showing that short dsDNA and poly-L-lysine coacervates can escape precipitation while displaying a surprisingly complex phase diagram, including the full set of liquid crystal (LC) mesophases observed to date in bulk dsDNA. LC-coacervate structure was characterized upon variations in temperature and monovalent salt, DNA and peptide concentrations, which allow continuous transitions between all accessible phases. A deeper understanding of LC-coacervates can gain insights to decipher structures and phase transition mechanisms within biomolecular condensates, to design stimuli-responsive multi-phase synthetic compartments with different degrees of order and to exploit self-assembly driven cooperative prebiotic evolution of nucleic acids and peptides. File list (6) download file view on ChemRxiv LC-Coacervates-chemRxive_final.pdf (4.63 MiB) download file view on ChemRxiv Figure 1.png (4.47 MiB) download file view on ChemRxiv SI_chemRxive_final_2.pdf (4.97 MiB) download file view on ChemRxiv Movie_S1.avi (212.88 KiB) download file view on ChemRxiv Movie_S2.avi (1.66 MiB) download file view on ChemRxiv Movie_S3_.avi (6.90 MiB)

Stability Against the Odds: the Case of Chromonic Liquid Crystals

“…which ranges in [0, 1], and making use of ( 19) in (6), we arrive at the following reduced functional, F [β], which is an appropriate dimensionless form of Frank's free-energy functional,…”

“…where κ 1 and κ 2 are the principal curvatures of ∂B, and n i are the components of n along the corresponding principal directions of curvature. 6 It is clear from ( 16) that for K 24 > 0, which is the strong form of ( 7), whenever ( 15) applies the saddle-splay energy would locally tend to orient n on ∂B along the direction of maximum (signed) curvature.…”

“…They are composed of plank-like molecules with a poly-aromatic core and polar peripheral groups, aggregated in columnar stacks resulting from noncovalent attractions between the poly-aromatic cores. CLCs are formed by certain dyes, drugs, and short nucleic-acid oligomers in aqueous solutions [1][2][3][4][5][6]. Their properties are reviewed in the following papers [7][8][9][10][11].…”

Increasing complexity of primitive compartments

“…Such structures and other functions may be affected by physical properties such as molecular crowding within the droplets [22][23][24], and as such, further demonstration of life-like functions within or by primitive membraneless droplets, such as catalytic cascades [25], primitive gene expression [26,27], or speciation [28] could lead to more understanding of the suitability of phase-separation as a relevant prebiotic compartmentalization method. To highlight recent work in the area of membraneless droplet assembly and function in our recent symposium, invited symposium speaker Tony Z. Jia (ELSI, Tokyo Institute of Technology and BMSIS) began with a discussion of a novel DNA liquid crystal coacervate droplets [19,20]. Invited speaker Shunsuke Tomita (National Institute of Advanced Industrial Science and Technology) then followed with a presentation about primitive DNA liquid crystal coacervates and nucleic acid scaffolds that undergo phase separation into liquid droplets [21].…”

“…Recent studies have found that more higher-order structures can assemble within peptide-DNA coacervates, leading to potential emergent functions with greater complexity depending on the environmental conditions and identity of the coacervate-forming polymers. For example, DNA liquid crystals can form within peptide-DNA coacervates upon sufficient concentration increases of the DNA and peptide components [ 19 ], potentially through environmental dehydration [ 20 ]. DNA quadruplex structures have also been found to promote phase separation and droplet formation for protein-DNA coacervates [ 21 ].…”