Award for Outstanding Doctoral Thesis Research in Biological Physics Talk: Single-stranded nucleic acid elasticity arises from internal electrostatic tension

The strong negative charge of single-stranded nucleic acids (ssNAs) means that an understanding of their biological roles (e.g., RNA folding) must account for electrostatic effects. ssNA flexibility means that, unlike for double-stranded nucleic acids, the characteristic structural and electrostatic length scales are in competition. We used single-molecule force spectroscopy to measure ssNA elasticity in the force range corresponding to these competing length scales. From these data, we developed an elastic model for flexible polyelectrolytes based on the internal electrostatic tension arising from the repulsion between backbone charges. This model better describes the elasticity of ssNAs than does the traditional Odijk-Skolnick-Fixman theory of electrostatics-dependent persistence length.