Illig, M. | bioRxiv Science

bioRxiv2023

Self-assembly and contraction of micron-scale DNA rings

Contractile rings formed from cytoskeletal filaments mediate the division of cells. The reverse-engineering of synthetic contractile rings could shed light on fundamental physical principles of the ring self-assembly and dynamics independent of the natural protein-based compounds. Here, we engineer DNA nanotubes and crosslink them with a synthetic peptide-functionalized star-PEG construct. The star-PEG construct induces the formation of DNA nanotube bundles composed of several tens of individual DNA nanotubes. Importantly, the DNA nanotube bundles curve into closed micron-scale DNA rings in a high-yield one-pot self-assembly process resulting in several thousand rings per microliter. The crosslinked DNA rings can undergo contraction to less than half of their initial diameter by two distinct mechanisms, triggered by increasing molecular crowding or temperature. DNA-based contractile rings expand the toolbox of DNA nanotechnology and could be a future element of an artificial division machinery in synthetic cells.

biophysics↗

bioRxiv2022

Mechanochemical signal transduction in synthetic cells

Mechanotransduction determines the adaptive response of natural cells via transmem-brane proteins1. The incorporation of membrane-spanning structures to guide cellular function and to enable transmembrane signalling is therefore a critical aim for bottom-up synthetic biology2,3,4. Here, we design membrane-spanning DNA origami signalling units (DOSUs) and mechanically couple them to DNA cytoskeletons5 encapsulated within giant unilamellar vesicles (GUVs). We verify the assembly and incorporation of the DOSUs into the GUV membranes and achieve their clustering upon external stimulation. The transmembrane-spanning DOSUs act as a pore to allow for the transport of single-stranded DNA into the GUVs. We employ this to externally trigger the reconfiguration of DNA cytoskeletons within GUVs using strand displacement reactions. In addition to chemical signalling, we achieve the mechanical coupling of the externally added DOSUs and the internal DNA cytoskeletons. We induce clustering of the DOSUs, which triggers a symmetry break in the organization of the DNA cytoskeleton which is mechanically coupled to the DOSU.Our work thus provides a mechanical and chemical transmembrane signaling module towards the assembly of stimuli-responsive and adaptive synthetic cells.

biophysics↗