Excerpts

To determine whether this improvement [replacing the N terminus with MDSTES and the C terminus with GSSGSS] extends to another FP, we examined mScarlet-I... The N-terminal peptide of mScarlet-I was replaced with MDSTEA because we found that MDSTES diminished the fluorescence (data not shown), and the C-terminal peptide was replaced with GGSGGS, yielding a variant that we termed mScarlet2-I. Although the difference between mScarlet-I and mScarlet-2I was less pronounced than the difference between mCherry and mCherry2C, the DH10B colonies expressing mSclarlet-2I were larger on average than those expressing mScarlet-I. The combined results indicate that the terminal peptides of EGFP can render some FPs cytotoxic.

We previously generated msGFP, a monomeric superfolder derivative of EGFP. Unfortunately, compared to EGFP, msGFP and other superfolder GFP variants show faster photobleaching. We now describe msGFP2, which retains monomeric superfolder properties while being as photostable as EGFP. msGFP2 contains modified N- and C-terminal peptides that are expected to reduce nonspecific interactions. Compared to EGFP and mEGFP, msGFP2 is less prone to disturbing the functions of certain partner proteins.