Quantitative Förster Resonance Energy Transfer (FRET)

uantification of Förster resonant energy transfer allows to measure precisely the amount of interacting proteins in a living cell and, for instance, determine the amount of protein - ligand bond formation at the surface of a cell. While typical FRET measurement based on donor and acceptor intensity provides only a qualitative picture of protein interactions in a specimen, the addition of spectral or lifetime information has been shown to improve greatly this situation. Spectral imaging allows to overcome one of the main drawback of dual channel detection scheme, which is the cross-talk between the channels, by providing a complete spectrum of the emitting species, which can be decomposed in contribution from the donor and acceptor dyes. Lifetime imaging provides a concentration independent measurement of the fraction of interacting species that it is not possible to access by simple intensity measurements.

We are working on different aspect of this problem. First of all, we are developing a reference FRET construct based on doubly labeled DNA strands to quantify precisely the efficiency of different imaging modalities to resolve FRET parameter. In the same time, we building a sixteen channel frequency modulated PMT that combines spectral and lifetime imaging in a single detector and will allow for a complete determination of the photo-physics of the FRET process in each pixel of the image.

Finally, as part of a mechanotransduction project, we are collaborating with the group of Prof Roger D. Kamm to quantify the interactions of proteins in focal adhesion complexes. We are studying the interaction of RFP-FAT and GFP-paxillin in epithelial cells.