Bacteria utilize sophisticated protein complexes to assemble structures that provide motility, adhere to multiple surfaces, and transfer DNA or effector molecules across membranes. Our research aims to understand, at a structural level, how these protein systems assemble and interact to affect infection and virulence, increase genetic diversity, and propagate resistance strategies.
One main area of focus of our research program is the type II secretion system (T2SS) that assembles the type IV pilus (T4P) in several organisms, including Pseudomonas aeruginosa. We have shown that truncated type IV pilins from P. aeruginosa are able to assemble into protein nanotubes (PNTs). We are focusing on: (a) a structural characterization the PNT assembly process in solution and at surfaces; (b) exploring the integration of the PNT architecture into functional biosensors and nanodevices; and (c) characterizing the sensing and signal transduction properties of the PNTs within the context of a functional biosensor targeting specific biochemical signals/triggers. We are also examining the T4P and T2SS assembly machinery used by other the bacteria such as Francisella tularensis and Coxiella burnetii. Both organisms have recently been shown to assemble T4P through associated T2SSs and that the pilus mediates adherence to cells during infection. In addition, methods for testing for Coxiella and Francisella infections are limited. Our research focuses on the structural characterization of the type IV pilins and T2SS component proteins of both F. tularensis and C. burnetii, primarily through X-ray crystallography, thereby providing structural and functional insights into the roles that these T4P play in surface adherence, their mechanisms of assembly, and the adaptability of these proteins for biosensor applications.
We are also exploring the type IV secretion system (T4SS) of the F plasmid from E. coli. This system is a main route for the transfer of DNA among a bacterial population, a process known as conjugation, which leads to greater diversity, adaptability and resistance to challenging environments. We are interested in understanding how the proteins of the F-T4SS interact structurally to assemble the conjugative pilus. These studies will provide a clearer picture into how these systems are assembled, leading to the design of new strategies to combat the spread of DNA through T4SS-mediated conjugation.
We are a member of York University’s Centre for Research on Biomolecular Interactions (CRBI).
Raj Bawa, Gerald F. Audette & Israel Rubinstein (eds.) Clinical Nanomedicine: Nanoparticles, Imaging, Therapy and Clinical Applications, Pan Sanford Series in Nanomedicine (R. Bawa, Series Editor), Pan Sanford Publishing, Singapore (2016)
Raj Bawa, Gerald F. Audette & Brian E. Reese (eds.) Handbook of Clinical Nanomedicine: Law, Business, Regulation, Safety and Risk, Pan Sanford Series in Nanomedicine (R. Bawa, Series Editor), Pan Sanford Publishing, Singapore (2016)
Lento, C., Wilson, D. & Audette, G.F. Dimerization of the type IV pilin from Pseudomonas aeruginosa strain K122-4 results in increased helix stability as measured by Time-Resolved Hydrogen-Deuterium Exchange. Structural Dynamics 3(1): 012001 (2016)
Shala, A., Patel, K. Golemi-Kotra, D. & Audette, G.F. Expression, Purification, Crystallization and Preliminary X-ray Analysis of the Receiver Domain of the Staphylococcus aureus LytR Protein. Acta Crystallog. F69, 1418-21 (2013)
Dudzik, J., Chang, W.-C., Kannan, A.M., Filipek, A., Viswanathan, S., Li, P., Renugopalakrishnan & Audette, G.F. Cross-Linked Glucose Oxidase Clusters for Biofuel Cell Anode Catalysts. Biofabrication 5: 035009 (2013)
Petrov, A., Lombardo, S. & Audette, G.F. Fibril-Mediated Oligomerization of Pilin-derived Protein Nanotubes. J. Nanobiotechnol. 11:24 (2013)
Petrov. A. & Audette, G.F. Peptide & Protein Nanotubes for Bionanotechnology. WIREs Nanomed Nanobiotechnol 4, 575-585 (2012)
Audette, G.F., Lombardo, S., Dudzik, J., Arruda, T.M., Kolinski, M., Filipek, S., Mukerjee, S., Kannan, A.M., Thavasi, V., Ramakrishna, S., Chin, M., Somasundaran, P., Viswanathan, S., Keles, R.S, & Renugopalakrishnan, V. Protein hotspots at bio-nano interfaces. Materials Today 14(7-8), 360-365 (2011)
Lombardo, S., Zahedijasbi, S., Jeung, S.-K., Morin, S. & Audette, G.F. Initial Studies of Protein Nanotube Oligomerization from a Modified Gold Surface. J. Bionanosci. 3(1), 61-65 (2009).
Kannan, A.M., Renugopalakrishnan, V., Filipek, S., Li, P., Audette, G.F. & Munukutla, L. Bio-Batteries and Bio-Fuel Cells: Leveraging on Electronic Charge Transfer Proteins. J. Nanosci. Nanotechnol. 9(3), 1665-1678 (2009).