We combine organic chemistry, molecular biology, protein engineering and directed evolution techniques to create tools that allow biologists to explore life in new ways. These tools are composed of two parts: a protein module and a synthetic small molecule. The advantage of using a protein module is that instructions for its manufacture can be easily and specifically introduced into cells in the form of DNA. In addition, its properties can be adjusted using protein evolution techniques. The interest of using a small synthetic molecule is to be able to use molecular engineering to refine its properties, and thus benefit from the power of modern chemistry to explore biological processes.
This original approach allowed us for instance to create FAST (Fluorescence-Activating and absorption-Shifting Tag), a new fluorescent reporter for biological imaging. FAST is a small genetically encoded protein tag of 14 kDa evolved from the Photoactive Yellow Protein (PYP). Using revolutionary directed evolution techniques, this protein has been redesigned to selectively and reversibly bind synthetic fluorogenic ligands (so-called fluorogens) from the hydroxybenzilidene rhodanine (HBR) family. These fluorogenic ligands strongly fluoresce only when bound to FAST, enabling to selectively image proteins fused to FAST without the need of washing the excess of fluorogenic ligand.
FAST presents various advantages over traditional GFP-like fluorescent proteins (instantaneous fluorescence maturation, small size and monomericity, oxygen-independence), opening new ways to study protein functions. Chromophore binding is non-covalent allowing labeling to be easily reversed by washing. In addition, because investigator can control fluorogen concentrations at will, it is possible to label only a subset of proteins independently of their expression level.
For further information see:
A small fluorescence-activating and absorption-shifting tag for tunable protein imaging in vivo.
Proceedings of the National Academy of Sciences (PNAS) 113 (3), 497-502 (2016)
M.-A. Plamont, E. Billon-Denis, S. Maurin, C. Gauron, F. M. Pimenta, C. G. Specht, J. Shi, J. Querard, B. Pan, J. Rossignol, K. Moncoq, N. Morellet, M. Volovitch, E. Lescop, Y. Chen, A. Triller, S. Vriz, T. Le Saux, L. Jullien & A. Gautier