Molecular Crowding Suppresses Mechanical Stress-Driven DNA Strand Separation.

ABSTRACT: Molecular crowding influences DNA mechanics and DNA - protein interactions and is ubiquitous in living cells. Quantifying the effects of molecular crowding on DNA supercoiling is essential to relating in-vitro experiments to in-vivo DNA supercoiling. We use single molecule magnetic tweezers to study DNA supercoiling in the presence of dehydrating or crowding co-solutes. To study DNA supercoiling, we apply a stretching force of 0.8 pN to the DNA and then rotate one end of the DNA to induce supercoiling. In a 200 mM NaCl buffer without co-solutes, negatively supercoiled DNA absorbs some of the torsional stress by forming locally melted DNA regions. The base pairs in these locally melted regions are believed to adopt a configuration where nucleotide base pairing is disrupted. We find that the

SUBMITTER: Desai PR 

PROVIDER: S-EPMC11661227 | biostudies-literature | 2025 Apr

REPOSITORIES: biostudies-literature