2YE0: X-ray structure of the cyan fluorescent protein mTurquoise (K206A mutant)

Cyan variants of green fluorescent protein are widely used as donors in Forster resonance energy transfer experiments. The popular, but modestly bright, Enhanced Cyan Fluorescent Protein (ECFP) was sequentially improved into the brighter variants Super Cyan Fluorescent Protein 3A (SCFP3A) and mTurquoise, the latter exhibiting a high-fluorescence quantum yield and a long mono-exponential fluorescence lifetime. Here we combine X-ray crystallography and excited-state calculations to rationalize these stepwise improvements. The enhancement originates from stabilization of the seventh beta-strand and the strengthening of the sole chromophore-stabilizing hydrogen bond. The structural analysis highlighted one suboptimal internal residue, which was subjected to saturation mutagenesis combined with fluorescence lifetime-based screening. This resulted in mTurquoise2, a brighter variant with faster maturation, high photostability, longer mono-exponential lifetime and the highest quantum yield measured for a monomeric fluorescent protein. Together, these properties make mTurquoise2 the preferable cyan variant of green fluorescent protein for long-term imaging and as donor for Forster resonance energy transfer to a yellow fluorescent protein.
PDB ID: 2YE0Download
MMDB ID: 98081
PDB Deposition Date: 2011/3/25
Updated in MMDB: 2017/09
Experimental Method:
x-ray diffraction
Resolution: 1.47  Å
Source Organism:
Similar Structures:
Biological Unit for 2YE0: monomeric; determined by author and by software (PISA)
Molecular Components in 2YE0
Label Count Molecule
Protein (1 molecule)
Green Fluorescent Protein
Molecule annotation
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Citing MMDB