title: Global analysis of Förster resonance energy transfer in live cells measured by fluorescence lifetime imaging microscopy exploiting the rise time of acceptor fluorescence.
abstract: A methodology is described for the quantitative determination of Förster resonance energy transfer (FRET) in live cells using the rise time of acceptor fluorescence as determined with fluorescence lifetime imaging microscopy (FLIM). An advantage of this method is that only those molecules that are involved in the energy-transfer process are monitored. This contrasts with current methods that measure either steady-state fluorescence of donor and acceptor molecules or time-resolved fluorescence of donor molecules, and thereby probe a mixture of donor molecules that are involved in FRET and those that are fluorescent but not involved in FRET. The absence of FRET can, for instance, be due to unwanted acceptor bleaching or incomplete maturing of visible proteins that should act as acceptor molecules. In addition, parameters describing the rise of acceptor fluorescence and the decay of donor fluorescence can be determined via simultaneous global analysis of multiple FLIM images, thereby increasing the reliability of the analysis. In the present study, plant protoplasts transfected with fusions of visible fluorescent proteins are used to illustrate the new data analysis method. It is demonstrated that the distances estimated with the present method are substantially smaller than those estimated from the average donor lifetimes, due to a fraction of non-transferring donor molecules. Software to reproduce the presented results is provided in an open-source and freely available package called "TIMP" for "The R project for Statistical Computing".
authors.affiliation: Laboratory of Biophysics, Wageningen University, Dreijenlaan 3 6703 HA Wageningen, The Netherlands.
authors.forename: Sergey P
authors.initials: SP
authors.lastname: Laptenok
authors.forename: Jan Willem
authors.initials: JW
authors.lastname: Borst
authors.forename: Katharine M
authors.initials: KM
authors.lastname: Mullen
authors.forename: Ivo H M
authors.initials: IH
authors.lastname: van Stokkum
authors.forename: Antonie J W G
authors.initials: AJ
authors.lastname: Visser
authors.forename: Herbert
authors.initials: H
authors.lastname: van Amerongen
mesh_terms: D000465:Algorithms; D002470:Cell Survival; D002477:Cells / Q000166:cytology* / Q000378:metabolism*; D005453:Fluorescence; D031541:Fluorescence Resonance Energy Transfer / Q000379:methods*; D008164:Luminescent Proteins / Q000032:analysis / Q000737:chemistry; D008856:Microscopy, Fluorescence; D059828:Plant Cells; D010944:Plants / Q000378:metabolism; D011523:Protoplasts / Q000166:cytology / Q000378:metabolism; D013997:Time Factors
chemical_list: D008164:Luminescent Proteins