Decoding Single Molecule Time Traces with Dynamic Disorder

PLoS Comput Biol. 2016 Dec 27;12(12):e1005286. doi: 10.1371/journal.pcbi.1005286. eCollection 2016 Dec.

Abstract

Single molecule time trajectories of biomolecules provide glimpses into complex folding landscapes that are difficult to visualize using conventional ensemble measurements. Recent experiments and theoretical analyses have highlighted dynamic disorder in certain classes of biomolecules, whose dynamic pattern of conformational transitions is affected by slower transition dynamics of internal state hidden in a low dimensional projection. A systematic means to analyze such data is, however, currently not well developed. Here we report a new algorithm-Variational Bayes-double chain Markov model (VB-DCMM)-to analyze single molecule time trajectories that display dynamic disorder. The proposed analysis employing VB-DCMM allows us to detect the presence of dynamic disorder, if any, in each trajectory, identify the number of internal states, and estimate transition rates between the internal states as well as the rates of conformational transition within each internal state. Applying VB-DCMM algorithm to single molecule FRET data of H-DNA in 100 mM-Na+ solution, followed by data clustering, we show that at least 6 kinetic paths linking 4 distinct internal states are required to correctly interpret the duplex-triplex transitions of H-DNA.

MeSH terms

  • Algorithms*
  • Computer Simulation
  • DNA / chemistry*
  • DNA / ultrastructure*
  • Fluorescence Resonance Energy Transfer / methods*
  • Kinetics
  • Models, Chemical*
  • Models, Molecular*

Substances

  • triplex DNA
  • DNA

Grants and funding

This study was partly supported by National Research Foundation of Korea 704 NRF-2015R1D1A1A01060376 ("https://www.nrf.re.kr"). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.