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Dr. Peter Pawelek

Assistant Professor

Dr. Peter Pawelek Dr. Peter Pawelek

Although iron is one of the most abundant elements on the planet, bacteria that require iron as an essential nutrient face an enormous challenge in obtaining enough of it in a bioavailable form. In soil, for example, the amount of free ferric iron is vanishingly small, and in a mammalian host most iron is already bound to proteins such as transferrin, hemoglobin, and ferritin.

In order to get at these precious iron sources, bacteria secrete molecules known as siderophores (the word comes from the Greek: sideros = “iron", phoros = "-bearing”).

Siderophores bind ferric iron with incredibly high affinity – high enough to soak up scarce ferric iron from the soil, or to strip an iron atom that’s already bound to a mammalian host protein. Once a siderophore has bound iron, bacteria employ a network of proteins to take up the iron-siderophore complex such that the iron can be eventually used in metabolic processes.

Dr. Peter Pawelek, an Assistant Professor in the Department of Chemistry and Biochemistry, studies how bacteria synthesize, secrete, and take up these highly effective iron-scavenging siderophore molecules. Because iron is such a limiting factor for most bacteria, it serves as a promising choke-point to target in the design of new antimicrobial compounds. A pathogenic bacterium that needs iron to proliferate inside a host during an infection can be effectively ‘disarmed’ by cutting off its iron supply. By understanding the proteins involved in siderophore synthesis, secretion, and uptake, Dr. Pawelek’s lab hopes to identify promising new targets for antibiotic development.

In addition to studying the siderophore systems of bacteria, Dr. Pawelek is also focusing on how bacteria can exploit favourable conditions in patients with iron overload disease resulting in opportunistic infections. Iron overload diseases such as thalassemia, a genetic disease in which a hemoglobin deficiency results in too much iron in the blood and tissues, are often treated with iron-chelating drugs such as Desferal. It’s now known that some pathogenic bacteria can ‘hijack’ iron-bound Desferal, being able to take up the iron-drug complex as a highly bioavailable iron source. Dr. Pawelek’s group is studying the cell-surface receptors that allow these bacteria to recognize and import iron-bound Desferal. By characterizing the three-dimensional shape of these receptors, it may be possible to design new compounds that can prevent this bacterial ‘iron hijacking’ in iron overload patients being administered this drug.

Dr. Pawelek’s research is funded by the Natural Sciences and Engineering Research Council of Canada (NSERC), and by the Thalassemia Foundation of Canada. In the past five years he has published in a number of high-impact journals including Science and The Journal of Molecular Biology. He is co-author of a book chapter in ‘Iron Deficiency and Overload: From Basic Biology to Clinical Medicine’ (Humana Press, 2009). Dr. Pawelek is also actively involved in the regional research community. He is currently leading the organization of the 10th Annual Symposium of PROTEO, which will be held at Concordia University on May 14, 2010. PROTEO is a Quebec network of over 40 protein scientists from universities across the province, including: Concordia University, Université Laval, Université de Montréal, McGill University, and Université de Sherbrooke.

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