New cyan fluorescent protein yields more sensitive cell imaging

March 22, 2012
Scientists at the Institut de Biologie Structurale/CNRS-CEA-Université Joseph Fourier have developed a molecule that emits turquoise light more efficiently than ever seen before in living cells, improving the sensitivity of cellular imaging.

Scientists at the Institut de Biologie Structurale/CNRS-CEA-Université Joseph Fourier (Grenoble, France) have developed a molecule that emits turquoise light more efficiently than ever seen before in living cells, improving the sensitivity of cellular imaging. The team—led by Antoine Royant—also comprised scientists from the University of Amsterdam in The Netherlands, the University of Oxford in England, and the European Synchrotron Radiation Facility (ESRF) in Grenoble.

An artistically inspired visualization of the 3-D X-ray structure of the cyan fluorescent protein mTurquoise2. (Image courtesy of Nature Communications/von Stetten/Royant/Goedhart)

First, using highly brilliant X-ray beams at the ESRF, the scientists from Grenoble and Oxford uncovered subtle details of how cyan fluorescent proteins (CFPs) store incoming energy and retransmit it as fluorescent light. They produced tiny crystals of many different improved CFPs and resolved their molecular structures. These structures revealed a subtle process near the so-called chromophore, the light-emitting complex inside the CFPs, whose fluorescence efficiency could be modulated by the environment. "We could understand the function of individual atoms within CFPs and pinpoint the part of the molecule that needed to be modified to increase the fluorescence yield," says David von Stetten from the ESRF.

Fluorescence microscopy image showing the actin filaments in a living cell. These filaments play an important role in muscle contraction. Here, mTurquoise2 proteins were fused to a small protein that attaches itself to the actin filaments. Thanks to the fluorescent light, vital process involving actin filament can be made visible in a living cell. (Image courtesy of Nature Communications/Goedhart)

In parallel to this work, the Amsterdam team, led by Theodorus Gadella, used an innovative screening technique to study hundreds of modified CFP molecules, measuring their fluorescence lifetimes under the microscope to identify which had improved properties.

The result of this rational design is a new CFP called mTurquoise2. By combining structural and cellular biology efforts, the researchers showed that mTurquoise2 has a fluorescence efficiency of 93%, enabling study of protein-protein interactions in living cells with unprecedented sensitivity. High sensitivity matters in processes where only a few proteins are involved and signals are weak, and in fast reactions where the time available for accumulating fluorescent light is short.

A tiny crystal of mTurquoise2 viewed with a microscope. mTurquoise2 crystals were used to study the atomic scale interactions that result in its high fluorescence efficiency. (Image courtesy of von Stetten/Royant/CNRS-ESRF)

Thanks to the team's approach, scientists now hope to design improved fluorescent proteins emitting light of different colors for use in other applications, concludes Royant.

The results of the work has been published in Nature Communications; for more information, please visit


Follow us on Twitter, 'like' us on Facebook, and join our group on LinkedIn

Follow OptoIQ on your iPhone; download the free app here.

Subscribe now to BioOptics World magazine; it's free!

Sponsored Recommendations

Next generation tunable infrared lasers

Nov. 28, 2023
Discussion of more powerful and stable quantum cascade tunable infrared lasers, applications, and test results.

What AI demands mean for data centers

Nov. 28, 2023
The 2023 Photonics-Enabled Cloud Computing Summit assembled by Optica took an aggressive approach to calling out the limitations of today’s current technologies.

SLP feature for lighting control available on cameras offering

Nov. 28, 2023
A proprietary structured light projector (SLP) feature is now available on the company’s camera series, including the ace 2, boost R, ace U, and ace L.

Chroma Customer Spotlight - Dr. David Warshaw, About his Lab

Nov. 27, 2023
David Warshaw, Professor and Chair of Molecular Physiology and Biophysics at the University of Vermont (UVM), walks us through his lab. Learn about his lab’s work with the protein...

Voice your opinion!

To join the conversation, and become an exclusive member of Laser Focus World, create an account today!