New Insights into DNA Structure

Single-molecule polarization microscopy of DNAintercalators sheds light on the structure of S-DNA

Researchers from Vrije University in Amsterdam and Sandia National Labs in New Mexico have used single-molecule polarization microscopy to uncover new details about the structure of S-DNA, an elongated DNA conformation. The group used both our 491-nm, 50-mW CW Cobolt Calypso and our 532-nm, 50-mW CW Cobolt Samba lasers for the imaging acquisition.

This study reveals that when DNA is mechanically overstretched, the intercalated dyes within the DNA adopt a tilted orientation relative to the DNA axis, providing the first experimental evidence of inclined base pairs in S-DNA.

The findings, published in the academic journal Science Advances, show that at extensions beyond the overstretching transition, the intercalators tilt at an angle of approximately 54° relative to the DNA axis, contrasting with the nearly perpendicular orientation at lower extensions. This discovery enhances our understanding of DNA’s physical properties and its behavior under mechanical strain, which has implications for genomic processes and the development of DNA-based technologies.