Département de biochimie
Function of the molecular architecture in enzymatic catalysis, macromolecular interactions and design of inhibitors
To understand how proteins and enzymes function at the molecular level and to translate this knowledge to disease states, we have focused our study on selective macromolecules functioning in metabolism and plant defence. The central metabolic pathway of glycolysis which is found in all living organisms converts glucose to metabolic intermediates that generate energy in form of ATP for cellular functions. The glycolytic enzyme we have studied most intensively is fructose 1,6-bisphosphate aldolase which cleaves a very specific C-C bond that is considered generally difficult to perform chemically. Aldolase has proven to be a rich source of fundamental knowledge on how enzymes perform their catalytic function and is casting a new perspective on the role of glycolysis in various cellular mechanisms. We are examining in particular the role of this enzyme in a number of diseases that involve extensive glucose utilization; these include cancer, protozoan infections (malaria, sleeping sickness, Leishmanias) and type II diabetes. Toxic secondary metabolites are generated during glycolysis which modify cellular proteins and these modifications have been implicated in a number of pathologies such as diabetes. Deglycation enzymes exist that can undo these types of modifications at the molecular level and are being investigated. Also of interest are related enzymes that cleave the same C-C bond however recognizing substrates that have subtly different substituent geometries about the cleaved bond. Understanding this differential cleavage activity has important application in controlling bacterial virulence. A more recent interest has been the DNA binding activity of plant transcriptional factors to improve plant resistance to disease. The experimental techniques we routinely use to explore biological structure at the molecular level are protein crystallography, molecular dynamics, and enzymology. A long standing interest has been the application of microgravity to protein crystal growth in order to alleviate this bottleneck in crystallographic studies. Protein purification, gene cloning and expression, site directed mutagenesis, enzyme kinetics, bioinformatics and cell culture are also experimental tools we use in our research.
- St-Jean, M., Sygusch, J. Stereospecific proton transfer by a mobile catalyst in mammalian fructose-1,6-bisphosphate aldolase. (2007) J. Biol. Chem. Oct 19;282(42):31028-37.
- Lafrance-Vanasse J, Sygusch J. Carboxy-Terminus Recruitment Induced by Substrate Binding in Eukaryotic Fructose Bis-phosphate Aldolases. (2007) Biochemistry. 46(33):9533-40.
- St-Jean M, Izard T, Sygusch J. A hydrophobic pocket in the active site of glycolytic aldolase mediates interactions with Wiskott-Aldrich syndrome protein. (2007) J. Biol. Chem. 282, 14309-14315.
- N, Coincon M, Sygusch J, Michels PA, Blonski C. Selective irreversible inhibition of fructose 1,6-bisphosphate aldolase from Trypanosoma brucei. J Med Chem. 2006 Mar 9;49(5):1499-502.
- St-Jean M, Lafrance-Vanasse J, Liotard B, Sygusch J. High resolution reaction intermediates of rabbit muscle fructose-1,6-bisphosphate aldolase: substrate cleavage and induced fit. J Biol Chem. 2005 Jul 22;280(29):27262-70.