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Ultrafast Structural Evolution and Chromophore Inhomogeneity inside a Green-Fluorescent-Protein-Based Ca(2+)
Longteng Tang1, Weimin Liu1, Yanli Wang1
1Department of Chemistry, Oregon State University , Corvallis, Oregon 97331, United States.
The Journal of Physical Chemistry Letters
|March 17, 2016
Summary
Researchers used advanced spectroscopy to study a calcium biosensor, revealing how its chromophore
Area of Science:
- Biophysics
- Spectroscopy
- Bioimaging
Background:
- Fluorescent protein biosensors are vital for calcium (Ca2+) imaging in biological systems.
- Understanding their excited-state dynamics is key to improving in vivo Ca2+ indicators.
Purpose of the Study:
- To elucidate the working mechanism and excited-state structural dynamics of the G-GECO1.1 calcium biosensor.
- To investigate the role of chromophore deprotonation and conformational changes in biosensor function.
Main Methods:
- Wavelength-tunable femtosecond stimulated Raman spectroscopy (FSRS) with a 530 nm Raman pump.
- Comparison of FSRS data obtained with 530 nm and 800 nm Raman pumps.
Main Results:
- Identified a chromophore two-ring twisting process (36/60 ps) competing with excited-state proton transfer (ESPT).
- Revealed an additional ESPT component (~5 ps) in a partially deprotonated chromophore subpopulation using the 530 nm pump.
- Confirmed dynamic differences in ESPT between Ca2+-free and Ca2+-bound states.
Conclusions:
- The study provides deep mechanistic insights into biosensor chromophore dynamics and subpopulation heterogeneity.
- Findings guide the rational design of improved fluorescent protein biosensors for metal ion imaging.
