Biosensor Optimization Using a Förster Resonance Energy Transfer Pair Based on mScarlet Red Fluorescent Protein and an mScarlet-Derived Green Fluorescent Protein.

Genetically encoded biosensors based on Förster resonance energy transfer (FRET) are indispensable tools for monitoring biochemical changes in cells. Green and red fluorescent protein-based FRET pairs offer advantages over the classically employed cyan and yellow fluorescent protein pairs, such as better spectral separation, lower phototoxicity, and less autofluorescence. Here, we describe the development of an mScarlet-derived green fluorescent protein (designated as mWatermelon) and its use as a FRET donor to the red fluorescent protein mScarlet-I as a FRET acceptor. We tested the functionality of this FRET pair by engineering biosensors for the detection of protease activity, Ca2+, and K+. Furthermore, we described a strategy to enhance the FRET efficiency of these biosensors by modulating the intramolecular association between mWatermelon and mScarlet-I.

Structure-activity relationship and bioactivity studies of neurotrophic trans-banglene.

The synthesis and bioactivity of neurotrophic banglenes and derivatives is described, establishing a structure-activity relationship which enables future mechanistic studies. Neuritogenesis assays indicate that (-) trans-banglene is the active enantiomer. Assays performed with and without NGF protein suggest that neurotrophic activity and potentiation of NGF activity by (-) trans-banglene might be distinct unassociated processes. Interestingly, (-) trans-banglene potentiation of NGF-induced neuritogenesis is unaffected by the presence of Erk1/2, Akt and Pkc inhibitors.