Explaining Nucleoprotein Polymerization Mass Photometry Data with Stochastic Modeling

RAD51 proteins bind to single-stranded DNA and are assembled into cooperative nucleoprotein filaments that are essential in DNA repair. In order to capture the stochastic nature of this process, we developed a Dynamic Monte Carlo simulation that models nucleoprotein polymerization on a DNA lattice.

To connect the simulation with mass photometry data, we applied Expectation-Maximization (EM) and Nonlinear least squares (NLS) fitting to fit Gaussian mixture models to model polymer size distributions.