Cytoplasmic Abundant Heat-Soluble Proteins from Tardigrades Protect Synthetic Cells Under Stress

Cytoplasmic abundant heat-soluble (CAHS) proteins, a stress-responsive intrinsically disordered protein from tardigrades, have been discovered to form gel-like networks providing structural support during dehydration, thus enabling anhydrobiosis. However, the mechanism by which CAHS proteins protect the dehydrating cellular membrane remains enigmatic. Using giant unilamellar vesicles (GUVs) as a model membrane system, we show that encapsulated CAHS12 undergoes a reversible structural transformation that reinforces membrane integrity and preserves encapsulated components, mimicking natural anhydrobiosis. CAHS12-containing GUVs demonstrated stability for weeks and mechanical robustness under dehydration, elevated temperature, and osmotic stresses. Molecular simulations suggest that CAHS12 forms a filamentous network within the vesicle lumen that mitigates membrane collapse and preserves compartmental architecture. Notably, removal of the N-terminal domain of CAHS12 abrogates this protective function. Synthetic cells with cell-free transcription-translation capabilities survive desiccation and recover biochemical activities, akin to the tun state of the tardigrade. This discovery opens up a protein-based strategy to impart synthetic cells with resilience to desiccation and other environmental stresses, expanding their utility in bioengineering, cold-chain-independent biomanufacturing, and adaptive biointerfaces.