​Fluorogenic Protein Labelling

​Special seminar hosted by Professor Guillaume Lessene

The fluorescent labelling of proteins, in vitro and in living cells, is a technique widely used to gain insight into their function, localization and trafficking.  We have developed a fluorescent labelling method based on the use of small synthetic fluorogenic molecules.  These fluorogens contain two maleimide groups that quench the latent fluorescence through an elucidated PeT mechanism, until they both undero thiol addition reactions. In parallel, we have designed short alpha-helical peptide sequences that present two appropriately positioned cysteine residues.  Proteins that are genetically encoded to bear one of these small de novo peptide tags (‘dC10α’) can then be selectively fluorescently labelled with our synthetic fluorogens.

Recently we have increased the reactivity of the peptide sequence by protein engineering, and tuned the reactivity of the dimaleimide fluorogens through substituent effects.  These efforts have allowed us to label specific proteins of interest, in the cytosol and in the nucleus of living cells, without the need for washing before fluorescent imaging.  Furthermore, by employing DFT calculations to predict orbital energies, we have designed highly fluorogenic labelling agents whose emission wavelengths are tuned to each of the channels of the fluorescent microscope – blue, green and red.

Jeffrey W. Keillor obtained his PhD in 1993 at the University of Alberta, studying enzyme model mechanisms under the supervision of Dr. R.S. Brown.  He then carried out postdoctoral studies in enzymology, under the direction of Dr. W.P. Jencks at Brandeis University.  In 1995 he took a position as assistant professor in the Chemistry Department at the Université de Montréal, where he was promoted to associate professor in 2000 and full professor in 2006.  He was also appointed as an adjunct professor in the Biochemistry Department in 2001.  In 2011 he moved to the University of Ottawa, where he currently holds a University Research Chair in Bioorganic Chemistry, in the Department of Chemistry and Biomolecular Sciences.

His research program is situated at the interface of chemistry and biochemistry, in the fields of chemical biology and medicinal chemistry.  His recent contributions have focussed on the development of novel site-specific protein-labelling methods and of targeted covalent inhibitors of tissue transglutaminase, for the treatment of cancer stem cells.  

In 2007 he won the Merck-Frosst Award for his contributions to organic chemistry and biochemistry, and in 2017 he won the Bernard Belleau Award for his work in the field of medicinal chemistry.  He was a member of the Board of the Canadian Society for Chemistry from 2012-2015 and served as Chair of its Biological & Medicinal Division from 2015-2017.