Single molecular investigation of the interactions between cationic short peptides and DNA

Intracellular liquid-liquid phase separation (LLPS) plays several crucial roles in cellular biology, including the regulation of biochemical reactions and gene expression.These processes can involve interactions between proteins (and/or peptides) and specific DNA sequences.In this study, we explored the interaction between DNA and two types of cationic peptides, polyarginine and polylysine, using magnetic tweezers (MT) and atomic force microscopy (AFM).We found that polyarginine is more effective at inducing DNA compaction than polylysine at the same concentration.We attribute this effect to polyarginine's greater efficiency in neutralizing DNA's surface charge, which was confirmed through electrophoretic mobility measurements using dynamic light scattering (DLS).Our study compares the effects of polyarginine and polylysine on DNA, revealing that polyarginine, despite having the same charge, has a superior ability to neutralize DNA's surface charge at equivalent concentrations.