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Examining the Conformational Dynamics of Membrane Proteins in situ with Site-directed Fluorescence Labeling
Published on: May 29, 2011
Minimum set of mutations needed to optimize cyan fluorescent proteins for live cell imaging
Marie Erard1, Asma Fredj, Hélène Pasquier
1CNRS, Univ Paris-Sud, Laboratoire de Chimie Physique, Orsay, France.
Molecular Biosystems
|November 30, 2012
Summary
Two mutations create Aquamarine, a high-performance cyan fluorescent protein (CFP) for live cell imaging. This optimized CFP enhances FRET biosensors, offering improved brightness and stability for cellular research.
Area of Science:
- Biochemistry
- Molecular Biology
- Cell Biology
Background:
- Cyan fluorescent proteins (CFPs) are crucial FRET donors in genetically encoded biosensors for live cell imaging.
- Recent advancements involve developing cyan variants with improved fluorescence quantum yields through large-scale mutagenesis.
Purpose of the Study:
- To investigate the impact of specific mutations on the performance of cyan fluorescent proteins (CFPs).
- To develop an optimized CFP variant for enhanced FRET-based biosensor applications.
Main Methods:
- Introduction of two specific mutations (T65S and H148G) into the ECFP framework.
- Characterization of the resulting variant, named Aquamarine, for its photophysical properties, pH stability, environmental sensitivity, and photoswitching behavior.
- Assessment of Aquamarine's performance as a FRET donor in mammalian cell systems and in a specific biosensor (AKAR).
Main Results:
- The T65S and H148G mutations confer high performance on ECFP, creating Aquamarine with a quantum yield of 0.89 and a fluorescence lifetime of 4.12 ns.
- Aquamarine exhibits excellent pH stability (pK(1/2) = 3.3), low environmental sensitivity, and undetectable photoswitching.
- Efficient and bright expression was observed in mammalian cells, with a stable fluorescence lifetime largely independent of fusion or location.
- Aquamarine successfully replaced CFP in the AKAR FRET biosensor for protein kinase A activity measurements.
Conclusions:
- A simple two-mutation strategy can significantly optimize CFP donor properties for FRET biosensors.
- Aquamarine offers superior performance characteristics, making it a valuable tool for live cell imaging and biosensing applications.
- This approach provides a rapid and effective method for enhancing FRET-based biosensor development.
