Genetically encoded sensors of protein hydrodynamics and molecular proximity.

The lumazine binding protein (LUMP) emits a cyan-colored fluorescence and has the longest average fluorescence lifetime of any genetically encoded fluorescent protein complex. Coupled with a small mass of 20 kDa, LUMP and its fusion with capture sequences are exploited as unique sensors of protein hydrodynamics and are shown to enable quantitative fluorescence anisotropy imaging of specific target proteins in vitro and in vivo. Moreover, the surface location of the lumazine probe is shown to improve the efficiency of Forster resonance energy transfer (FRET) with the Venus acceptor protein compared with CFP, which is used in the development of a new class of FRET-based sensor.