Biophysical Society Thematic Meeting | Tutzing 2026

Single-Molecule FRET: The Next 30 Years

Poster Abstracts

32-POS Board 16 SINGLE-MOLECULE FRET CORRELATIONS REVEAL RAPID LOCAL DIFFUSION OF NEIL1 ON DNA Jan-Philipp Krämer-Günther 1 ; Soundhararajan Gopi 1 ; Andrea Holla 1 ; Lucas Kirchen 1 ; Robert Best 2 ; Daniel Nettels 1 ; Benjamin Schuler 1,3 ; 1 University of Zurich, Department of Biochemistry, Zurich, Switzerland 2 National Institutes of Health, Laboratory of Chemical Physics, Bethesda, MD, USA 3 University of Zurich, Department of Physics, Zurich, Switzerland Efficient target search on DNA is important for a wide range of regulatory processes in the cell. Quantifying this biomolecular diffusion on nanometer length scales and microsecond timescales remains a major experimental challenge. While single-particle tracking resolves long-range motion, local diffusion processes underlying target search on DNA are difficult to access directly. Here, we introduce a framework to extract quantitative diffusion coefficients from single-molecule Förster resonance energy transfer (smFRET) correlation measurements. Using a combination of smFRET and analytical modeling, we show that both the timescales and amplitudes of fluorescence correlations encode information about nanoscale motion. By rigorously correcting correlation amplitudes for photophysical effects and fitting a physical model of diffusion on a cylindrical surface, we directly obtain diffusion coefficients and geometric constraints with minor prior assumptions about the system. We validate this approach using the DNA repair protein NEIL1 as a model system. Coarse-grained molecular dynamics simulations support the smFRET data and provide mechanistic insights into how these processes occur at the molecular level. This smFRET correlation method provides access to a previously inaccessible regime of biomolecular dynamics and establishes smFRET correlation analysis as a general tool for probing nanoscale diffusion processes in DNA–protein interactions.

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