Research in my lab is focused on understanding how proteins function, by studying their atomic resolution structures. Using protein X-ray crystallography as a tool for elucidating structures, we combine structural studies with enzymology, site-directed mutagenesis and computer-aided design of inhibitors to understand how proteins function. The determination of the 3-D structures of proteins and their complexes enable us to answer important questions about how these proteins function, and how they interact with their substrates and each other.
At the University of Saskatchewan, we are ideally placed to carry out this research, due to the presence of the Canadian Light Source, Canada's own synchrotron light source, and the Saskatchewan Structural Sciences Center, a facility equipped with instruments for biophysical characterizations of macromolecules.

The major area of research in my lab is to understand enzymes that have important roles in pathogenic microorganisms. We are studying these enzymes to determine their function and design inhibitors that could potentially act as lead compounds for drug development. We are studying novel enzymes found in bacteria and other pathogenic microorganisms.
The development of multi-drug resistant (MDR) bacteria mean that the current lines of antibiotic agents will become less and less effective against common bacterial infections. It will be important to investigate potential new targets to develop novel ways of combatting pathogenic microorganisms. The bacterial cell wall has long been a target for antibacterial compounds, including the β-lactams. The cell wall of most bacterial species consists of combinations of sugar residues, many of them unique to bacteria. Targeting the biosynthetic pathways that produce the novel sugar residues is an attractive drug target as these pathways will not exist in the host organism, limiting the side-effects. Some of these sugars also exist in other pathogenic microorganisms, increasing their potential as drug targets.
Different bacteria also are found that produce their own antibiotic agents. These antibiotics are often very different than other compounds and offer a unique opportunity to study enzyme reactions. These pathways often include unique enzymes involved in their biosynthesis and we are currently studying two biosynthetic pathways.
We also study several enzyme systems to fundamental structure-function questions. While these systems may not have any direct applications in human health, the fundamental underlying principles will be important to many systems.

We are currently studying a number of different systems in my lab:
1. Enzymes responsible for interconversion of sugar rings
2. Enzymes in the biosynthesis of unusual antibiotics
3. Inositol metabolism
4. Protein-protein interactions


1. Interconversion between pyranose and furanose sugar forms
One unusual reaction that is carried out by a number of microorgansism is the interconversion between the pyranose and furanose forms of different sugars. The best characterized enzyme in this family is UDP-Galactopyranose Mutase (UGM). UDP-galactopyranose mutase converts UDP-galactopyranose (UDP-Galp) to UDP- galactofuranose (UDP-Galf). UDP-galactofuranose is the precursor to galatofuranose residues found in the cell wall of many pathogenic microorganisms, including Escherichia coli, Klebsiella pneumonia and Mycobacterium tuberculosis. UGM functions through the use of a flavin adenine dinucleotide (FAD) cofactor, though no net redox occurs with this reaction. We have determined the structures of a number of different UGMs, both with and without substrates and are currently using these structures to understand the mechanism of this enzyme and to begin developing novel inhibitors, using computer-aided drug design.
Recently, enzymes that carry out similar reactions on different sugars have been identified. The first characterized was UDP-N-Acetyl-Galactose Mutase (UNGM) This enzyme can convert both UDP-GalpNAc and UDP-Galp to the corresponding furanose form. UGM on the other hand cannot convert UDP-GalpNAc. We are currently determining the structures of these other mutase enzymes to understand the determinants of substrate specificity.
A related enzyme has been identified in plants. This enzyme, UDP-Arabinofuranose Mutase (UAM) is closely related to UGM (including substrate specificity), but it is not a flavor-dependent enzyme. Instead, this enzyme utilizes a metal cofactor to carry out the ring interconversion. We are studying this enzyme to understand the way this enzyme has evolved to carry out the same reaction using a different structure.

2.Unusual Antibiotics
Microorganisms often produce compounds that act as antimicrobial agents. Many of the antibiotics used today originated from bacteria of fungi (for example, penicillin). There are many other compounds that are less well-known or understood. One area of research is to understand how these compounds are produced in these microorganisms. We are currently studying the biosynthesis of two of these compounds, neotrehalosadiamine (NTD) and jadomycin (Jad). NTD is produced by the bacteria Bacillus subtilis by the genes of the NTD operon. We are determining the structures of the enzymes of this operon, to aid in understanding how NTD is synthesized. Jad is produced by Streptomyces venzuelae. One of the proteins involved in Jad biosynthesis is JadX, which is believed to be a transcription factor. We are determining the structure of this protein to understand its role and ways that it is regulated.

3.Inositol metabolism
Inositols are important natural products that perform a variety of roles in human and animal physiology. There has been considerable focus on inositol phosphates, which are important second messengers, although inositol isomers myo-inositol and D-chiro-inositol play a role in nutrition, insulin sensitivity and ovarian health. There has been relatively little attention paid to inositol-manipulating enzymes other than the phosphatases. We are currently investigating the structure-function relationships of enzymes that catalyze reactions involving inositol and inositol-related substrates. The initial enzyme that we have studied is myo-inositol dehydrogenase (IDH) from Bacillus subtilis, which catalyzes the NAD+-dependent oxidation of myo-inositol to scyllo-inosose.

4.Protein-protein Interactions
The study of protein-protein interactions is a tremendously large field, but the presence of both the Canadian Light Source and the Saskatchewan Structural Sciences Centre places us in a wonderful position to be able to carry out numerous studies on the molecular basis of how macromolecular assemblies are formed, and the forces that are required to allow molecules to specifically recognize each other and form complexes. Thioredoxins (Trx) are part of the other ubiquitous redox-regulating system and act through Thioredoxin Reductase (TrxR) to reduce protein disulfide bonds. Despite highly similar structures, these systems show species specificity in their recognition, as the proteins from the same organism show better recognition than those from different organisms. We are currently determining the structures of the main components of this system (Trx and TrxR) from different extremophiles (bacteria that grow in hot or cold environments). Our goal is understand how these proteins recognize each other and what contributes towards the recognition specificity.




If you are interested in research in one of the most exciting fields of chemistry and biochemistry, I am always interested in talking to both graduate and undergraduate students. Opportunities for graduate students and summer research positions are always available !