Protein Translocation Using Chimeric Toxins

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With this award, the Chemistry of Life Processes Program in the Chemistry Division is funding Dr. Andrew Feig from Wayne State University to study a new approach to using chimeric proteins that can spontaneously transport themselves across the cellular membrane of eukaryotic cells. The chimeric proteins will be built using a scaffold based on toxins from Clostridium difficile. These toxins kill host cells by transporting a glucosyltransferase that initiates apoptosis by modifying cellular G-proteins. The Feig team works to remove the natural catalytic domain and replace it with designed cargos. This is expected to allow for the delivery of metabolically active proteins in lieu of the natural cargo domain. Chimeras are to be optimized to improve their delivery properties and test the limits to which this technology can be pushed to regulate cellular functions by direct protein delivery to cells. In addition, the possibility to replace the domain of the toxin that normally binds the cell surface with fragments that recognize specific receptors is being explored. The goal is to effectively target cargo delivery to only those cells expressing the designated partner. This would achieve a holy grail of protein delivery since it would provide tunable cell selectivity and deliver tagless proteins directly to the cytosolic compartment. Scientists have, for many years, manipulated cells to study the way in which individual proteins contribute to cellular functions. However, a major limitation of this approach is that one is limited to those building blocks available in the cell since the proteins are still translated by the ribosome. This work will further develop technology that was recently put forth by the Feig Lab that allows properly designed proteins to transport themselves across the cell membrane releasing an active protein in the cytosol without any residual tags. There are many potential uses for such technology including the targeted delivery of protein therapeutics, the delivery of modified proteins that can be easily tracked within the cell to study their fate and the manipulation of cellular pathways. The project will be integrated with faculty development work that the principal investigator is involved with that trains new faculty in the fields of Chemistry and Biochemistry to use evidence-based teaching methods in the classroom and to better assess the quality of student learning in real-time.