Oligolysine Promotes and Inhibits DNA Condensate Formation

The formation of biomolecular condensates via phase separation is crucial for cellular functions. Reconstituting these condensates with designed molecules allows for exploring their mechanisms and potential applications. Sequence-designed DNA nanostructures enable the investigation of the effects of structural design on condensate formation and construction of functional artificial condensates. Although DNA-based condensates have high designability, free nanostructures not assembled into condensates remain dispersed in solution. Herein, we report the effects of cationic oligolysines on DNA condensation. Our aim was to decrease the electrostatic repulsion between DNA nanostructures using oligolysines. Experimental results showed that DNA condensate formation was enhanced at an appropriate negative/positive charge (N/P) ratio. Surprisingly, oligolysines significantly inhibited condensate formation depending on the N/P ratio and residue number. Molecular dynamics simulations revealed that the deformation of the nanostructures induced by oligolysines likely caused this inhibition. We confirmed that the DNA condensates with oligolysines maintained sequence specificity in their interactions to demonstrate the applicability of the peptide/DNA hybrid condensates. These findings provide insights for further development of DNA/peptide hybrid condensates to enhance the functions of artificial condensates for use in artificial cells and molecular robots.