Efthymia Prifti


Name: Efthymia “Fay” Prifti
Nationality: Greece

Ecole Polyechnique Federale de Lausanne
Laboratory of Protein Engineering
BCH4218 (Bat. BCH)
CH-1015 Lausanne

Contact details: efthymia.prifti@epfl.ch, +41 (0)21 693 9443 


Fay Prifti was born in Athens, Greece and has studied Pharmacy at the University of Athens. She had always intended to pursue a career related to research, which is why during her studies, she made an effort to expose herself to different science related disciplines, in order to decide which field she would be most interested in pursuing her PhD in. She was very fortunate to have the opportunity of doing undergraduate research at the Pharmacy School of Athens, at the Laboratory of Pharmacognosy and Natural Products Chemistry, as well as at three other research labs abroad. In the summer of 2009, she had an excellent opportunity to spend two months in the Dept. of Pathology at the University of Cambridge, UK (Amgen summer Scholarship). She worked on the project “Salmonella tyrosine phosphatase SptP downregulation of the host actin cytoskeleton” with Prof. Vassilis Koronakis.

She was also selected to participate in the John Innes Undergraduate Summer Research Programme, UK, where she worked in the Dept. of Biological Chemistry on the project “Chemical tools to dissect plant cell wall biosynthesis” with Prof. Rob Field. Finally, she decided to do her diploma thesis as part of an Erasmus Scholarship in the Dept. of Pharmacology at Cardiff University, Wales, UK in the laboratory of Dr Emma Kidd. Her thesis was titled “Caveolins and Alzheimer’s disease”.

Having studied Pharmacy, Fay has developed a strong organic chemistry background but has also gained experience in a broad spectrum of other natural and health sciences, including biochemistry, pharmacology and biology. Her technical expertise includes cell culture, immunohistochemistry, fluorescence microscopy, molecular biology, enzymology, protein expression and purification, organic chemistry.

She is now based in EPFL in Prof. Kai Johnsson’s lab where she is working on the development of fluorescent sensors for membrane proteins and lipids.

When not in the lab, she enjoys dancing salsa and travelling around the world.

Project title: Fluorescent sensors for membrane proteins and lipids

Project summary:

My project has 2 parts. First of all, I am interested in developing a sensor for ceramides and secondly in developing fluorescent probes for membrane proteins.

Concerning the first part of the project, I would like to develop a sensor for ceramides based on the Snifit (SNAP-tag based indicator proteins with a fluorescent intramolecular tether) concept. Snifits are fusion proteins consisting of SNAP-tag, CLIP-tag, and a receptor protein. SNAP- and CLIP-tag, two self-labeling protein tags, are labeled with a synthetic fluorophore tethered to a receptor protein ligand and a second synthetic fluorophore, respectively. The ligand binds to the receptor protein and maintains the Snifit in a closed conformation. A free analyte competes for binding to the receptor protein and can shift the equilibrium towards an open conformation. The conformational change results in reduced proximity of the two fluorophores and hence a change in their FRET efficiency. So, the first step, for this part of the project, is to optimize the structure of the sensor (Identify binding protein of interest: CERT, identify the ligand- which has to be a ceramide substitute- like (1R,3R)-HPA-12). Then, the monitoring of ratiometric changes in fluorescence when incubating sensor with ceramide in vitro is essential.

The aim of the second part of my project is the development of a fluorogenic probe for cell membrane proteins, based on the solvatochromic molecule Nile Red. Nile Red is a molecule that is almost non-fluorescent in aqueous solution whereas in an apolar environment, like the membrane, its fluorescence quantum yield reaches values close to unity. It has a high affinity for the membrane and it has been used for the staining of lipid droplets. The idea is to decrease the affinity of Nile Red for the membrane by chemically derivatizing with a ligand, so that it would insert into the membrane only when this ligand binds to a specific target receptor. The result could be a probe that turns fluorescent only upon binding to a specific membrane protein (such as EGFR and GABAB). Also, the fact that it is non-fluorescent in aqueous solution supports one other important aim of this part of the project, which is the generation of highly specific “no wash” probes for the labeling of cell surface SNAP fusion proteins that will have superior labeling rates than other approaches that have been previously described (Komatsu, JACS 2011).

This project is supervised by Prof. Kai Johnsson and performed by Fay Prifti at EPFL, Switzerland.


Kai Johnsson (EPFL, Lausanne, Switzerland)
Howard Riezmann (University of Gevena, Switserland)

Biosketch 1st scientific supervisor:

Kai Johnsson is a faculty member at the Institute of Chemical Sciences and Engineering (ISIC) of the Ecole Polytechnique Fédérale de Lausanne (EPFL), Switzerland. His laboratory is interested in protein engineering, and in particular in the development of tools to study and manipulate the biological function of proteins and small molecules in vivo and in vitro. Kai Johnsson is the co-director of the National Centre of Competence in Research (NCCR) «Chemical Biology – Visualisation and Control of Biological Processes Using Chemistry». He is an Associate Editor of ACS Chemical Biology, member of the editorial board of Chemistry & Biology, member of the advisory board of Chemical Society Reviews and Member of Faculty of 1000. He is co-founder of Covalys Biosciences, a company based on protein labeling technologies developed in his laboratory and now available through New England BioLabs. He received the EPFL Prix APLE for the invention of the year 2003.Two SPHINGONET projects are carried out under his supervision: “Development of a novel drug target-profiling platform in yeast” (link) and “Development and application of semi-synthetic sphingolipid sensors” (link)