The possibility of bacteriochrome-based infrared fluorescent protein iRFP use as an acceptor for the Förster resonance energy transfer (FRET) was investigated. GFP-like far-red fluorescent proteins mKate2, eqFP650, and eqFP670 were used as energy donors. Bacterial expression vectors encoding donor and acceptor proteins joined by a heptadecapeptide linker were constructed with the goal to test FRET. The efficiency of FRET was estimated in vitro for the isolated proteins from the increase of the donor emission following cleavage of the linker. Among the three tested constructs the eqFP650-iRFP pair demonstrated the most efficient energy transfer (approximately 30%).
- fluorescent protein
- genetically encoded sensor