We are studying the relationship between structure and function in three different types of proteins: antifreeze proteins (AFPs), which help organisms to resist or tolerate freezing; bacterial adhesins, which play a role in biofilm formation and infection; and calpains, enzymes that selectively cut proteins within the cell in response to calcium signals. (Funded by CIHR and NSERC)
Antifreeze proteins are found in some fishes, insects, plants and microorganisms. They bind to ice crystals and prevent them from growing to a size where they would damage the host. Our research involves the isolation and characterization of antifreeze proteins from different sources, the study of their evolution, and the cloning and expression of their genes to produce recombinant proteins for 3-D structural analysis by NMR and/or X-ray crystallography. AFPs are proving to have remarkably diverse structures. We are trying to identify their ice-binding sites/residues using site-directed mutagenesis in order to learn more about their mechanism(s) of action and what structural features are required for binding to ice. We are also engineering superior AFPs based on this information, and are applying them to the sub-zero storage of organs, tissues and cells.
Bacterial adhesins are long, thin proteins attached to the outer membrane of bacteria, which anchor their hosts to various surfaces where the bacteria can form biofilms. Structural characterization and functional analysis of all the adhesins are revealing methods for blocking biofilm formation that will be useful in preventing infections.
Calpains are complex, multi-domain calcium-dependent proteases involved in calcium signaling. We are studying their mechanism of activation and inhibition, and are using peptide and combinatorial compound libraries to develop calpain-specific inhibitors and substrates. The latter will be used to better define the physiological roles of calpain, and as leads for developing drugs to help prevent the calpain-mediated damage associated with heart attacks, stroke, neurodegeneration, and muscular dystrophy.