The official start date of my tenure-track position was Jan. 25, 2015 and I will focus on describing the progress after this time. The progress of research with Dr. Eaton prior to this period can be found in Dr. Eatons report. In single molecule Frster resonance energy transfer (FRET) spectroscopy, kinetics and dynamics of molecular processes are typically determined by analyzing energy transfer efficiency calculated using fluorescence intensity from donor and acceptor fluorophores. To understand complex molecular interactions and conformational changes during binding and oligomerization processes, it is important to utilize all available information from single molecule measurements. Since FRET efficiency is related to the lifetimes of fluorophores, additional information of the process can be extracted by analyzing fluorescence intensity and lifetime together. However, for a fast process where individual states are not well separated in a single molecule trajectory, it is not simple to obtain lifetime information. In collaboration with Dr. Irina V. Gopich, we have been developing analysis methods that utilize both fluorescence intensity and lifetime information. 2D FRET efficiency-lifetime histogram method visualizes the correlation between the FRET efficiency and mean fluorescence delay times (fluorescence lifetimes), which reveals the presence of the sub-microsecond dynamics in each state and the microsecond to millisecond kinetics between states. A more quantitative analysis method is the maximum likelihood method that analyzes photon trajectories to determine the FRET efficiencies and the kinetics and lifetime parameters accurately. These approaches will be very useful for complex multi-color single molecule FRET studies of binding and oligomerization processes in the future.
| Chung, Hoi Sung (2018) Transition Path Times Measured by Single-Molecule Spectroscopy. J Mol Biol 430:409-423 |
| Chung, Hoi Sung; Meng, Fanjie; Kim, Jae-Yeol et al. (2017) Oligomerization of the tetramerization domain of p53 probed by two- and three-color single-molecule FRET. Proc Natl Acad Sci U S A 114:E6812-E6821 |
| Chung, Hoi Sung; Louis, John M; Gopich, Irina V (2016) Analysis of Fluorescence Lifetime and Energy Transfer Efficiency in Single-Molecule Photon Trajectories of Fast-Folding Proteins. J Phys Chem B 120:680-99 |
