Quantitative fluorescence resonance energy transfer measurements using fluorescence microscopy

Area of Science:

• Biophysics
• Cell Biology
• Molecular Imaging

Background:

• Fluorescence resonance energy transfer (FRET) quantifies molecular distances using fluorophores.
• FRET microscopy combined with mutant green fluorescent proteins (mtGFPs) enables in vivo molecular interaction studies.
• Standard FRET measurements can be distorted by acceptor excitation and concentration-dependent effects.

Purpose of the Study:

• To present a simple, corrected method for analyzing FRET data from standard fluorescence microscopes.
• To address distortions including cross-talk and concentration dependence in FRET measurements.
• To validate the method using the interaction between Bcl-2 and Beclin proteins.

Main Methods:

• Utilized standard filter sets in fluorescence microscopy for FRET data acquisition.
• Developed an analysis method to correct for cross-talk between donor and acceptor signals.
• Implemented corrections for the dependence of FRET efficiency on donor and acceptor concentrations.

Main Results:

• The presented method accurately corrects for cross-talk and concentration effects in FRET measurements.
• Demonstrated the method's efficacy by analyzing the interaction of Bcl-2 and Beclin proteins.
• Quantitative spatial and temporal data on molecular interactions can be reliably obtained.

Conclusions:

• This corrected FRET analysis method enhances the accuracy of molecular interaction studies in living cells.
• The approach is applicable to various intracellular molecular species, including proteins, lipids, DNA, and RNA.
• Accurate FRET measurements are crucial for understanding cellular processes and disease mechanisms.