FRET Analysis of Protein-Lipid Interactions

Abstract

Forster resonance energy transfer (FRET) is an old but constantly developing spectroscopic tool possessing enormous potential for studies on structure and dynamics of biological macromolecules and their assemblies. One of the main advantages of FRET technique is the possibility of measuring the nanometer-scale distances between donor and acceptor fluorophores. This chapter highlights some aspects of FRET-based monitoring of intermolecular interactions in membrane systems. Analytical model of energy transfer between membrane-associated donors and acceptors randomly distributed over parallel planes separated by a fixed distance is presented. The factors determining the efficiency of energy transfer are considered with special attention to orientational behavior of the donor emission and acceptor absorption transition dipoles. It is demonstrated that FRET can provide proof for specific orientation of the protein molecule relative to lipid-water interface. The applications of FRET to quantification of protein-lipid binding parameters and membrane position of protein fluorophores are exemplified. It is illustrated how FRET may help in obtaining evidence for protein aggregation in a membrane environment and domain formation.