Chemical Biology of Transglutaminases

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Enzymes are proteins that catalyse almost all of the chemical reactions necessary to support life. Enzymes are known to show a high degree of specificity with respect to the molecules that they recognize and transform, known as substrates. In order to understand the biological role of an enzyme, it is essential to first understand its specificity, and the nature of the transformation it catalyses.******The transglutaminases (TGases) are a family of eight enzymes that have been implicated in a wide variety of important physiological processes. However, we still have a limited understanding of which of these different TGases catalyse which reactions, and with which substrates. For example, they all catalyse either the cross-linking of different proteins, or the reversible attachment of biological amines to those proteins, but we don't know which TGases modify which proteins, in what way, and in which tissues.******The Keillor group is uniquely qualified to answer these questions. We have many years' experience studying tissue TGase (TG2), and have recently discovered how to make small molecules that will react specifically with TG2, and not with other TGases. This has led to a breakthrough in understanding how TG2 plays a role in cancer metastasis. Over the next granting period, we will apply the same approach, to make molecules that will react specifically with three additional members of the TGase family: Factor XIII, TG1 and TG3. ******TG1 and TG3 are both thought to play roles in the stabilization of skin; however, the excess activity of one and the deficiency of the other have both been implicated in skin disorders. Factor XIII circulates in the blood and assists in the coagulation process, but it is also involved in bone development and in clotting disorders. For each of these four TGases, we will 1) determine their specificity, 2) develop novel methods for measuring their specific activity, 3) develop inhibitors for blocking their specific activity, and 4) develop molecular probes that will reveal where the enzymes and their substrates are located, in living cells. Achieving these objectives will allow us to dissect the related activities of these important enzymes, to discover their unique biological roles and to guide the future treatment of physiological disorders related to their unregulated activity.******The detailed methods required to achieve these multidisciplinary objectives are numerous, but they are all inherent in our current research program. We routinely employ organic synthesis, molecular biology, protein biochemistry, bioanalytical techniques, kinetic studies, mammalian cell culture and fluorescence microscopy. Trainees in the Keillor group will therefore have the opportunity to be trained across a broad array of highly relevant techniques, rather than specializing in just one. This will prepare them very well for impactful positions in the modern biotech or pharmaceutical industries, or in academia.