Areas of Interest
Extracellular secretion of proteins is one of the primary virulence mechanisms in bacterial infection. Gram-negative bacteria pathogenic for humans, animals and plants secrete a number of proteins that are responsible for causing disease. Several different secretion pathways have evolved for this purpose. The type II secretion system (T2SS) has been identified in pathogens such as Vibrio cholerae, Escherichia coli O157, Pseudomonas aeruginosa, Legionella pneumophila, Yersinia enterocolitica and more recently, Acinetobacter baumannii, where it is responsible for secretion of toxins and hydrolytic enzymes including proteases and lipases.
The main goals of our studies are to determine the mechanism of secretion and to characterize the T2S machinery and its secreted substrates so that we may identify novel ways to manipulate the secretion process for preventative, therapeutic and biotechnological use. For our studies we use two different model systems: Vibrio cholerae, the causative agent of cholera, which is a life-threatening diarrheal disease endemic to many developing countries, and Acinetobacter baumannii, an opportunistic pathogen known for its persistence in hospital settings and multidrug resistance. We focus on three main areas of research. We perform structure-function analysis of the T2SS, which is comprised of 13-15 different proteins. We run proteomic screens to identify proteins that are specifically secreted via the T2SS during virulence-inducing conditions as well as during environmental growth conditions and determine their functions. In addition, we perform high throughput screening of chemical libraries to identify small molecule inhibitors of the T2SS. This basic-translational research will generate new tools to be used to study the mechanism of secretion. They will also be exploited for development of alternatives to antibiotics to combat multi-drug resistant gram-negative pathogens.
Sandkvist, M. and Korotkov, K.V. Architecture, function, and substrates of the type II secretion system. EcoSal Plus, doi: 10.1128/ecosalplus.ESP-0034-2018, 2019.
Waack, U., Warnock, M., Yee, A., Huttinger, Z., Smith, S., Kumar, A., Deroux, A., Ginsburg, D., Mobley, H.L.T., Lawrence, D.A., and Sandkvist, M. CpaA is a Glycan-Specific Adamalysin-like Protease Secreted by Acinetobacter baumannii that Inactivates Coagulation Factor XII. mBio 9:e01606-18, 2018.
Gadwal, S., Johnson, T.L., Remmer, H., and Sandkvist, M. C-terminal processing of GlyGly-CTERM containing proteins by rhombosortase in Vibrio cholerae. PLoS Pathogens 14: e1007341, 2018.
Waack, U., Johnson, T.L., Chedid, K., Xi, C., Simmons, L.A., Mobley, H.L.T., and Sandkvist, M. Targeting the Type II Secretion System: Development, Optimization, and Validation of a High-Throughput Screen for the Identification of Small Molecule Inhibitors. Frontiers in Cellular and Infection Microbiology 7:380, 2017.
Johnson, T.L., Waack, U., Smith, S., Mobley, H., and Sandkvist, M. 2016. Acinetobacter baumannii is dependent on the Type II Secretion System and its substrate LipA for lipid utilization and in vivo fitness. J. Bacteriol. 198:711-719.
Korotkov, K.V., Sandkvist, M., and Hol, W.G.J. 2012. The type II secretion system: biogenesis, molecular architecture and mechanism. Nature Review Microbiology, 10:336-351.
Sikora A.E., Zielke, R., Lawrence, D.A., Andrews, P., and Sandkvist, M. 2011. Proteomic analysis of the Vibrio cholerae type II secretome reveals new proteins including three related serine proteases. J. Biol. Chem., 286:16555-16566.
Lybarger, S.R., Johnson, T.L., Gray, M., Sikora, A.E., and Sandkvist, M. 2009. Docking and assembly of the Type II secretion complex of Vibrio cholerae. J. Bacteriol., 191:3149-3161.
Camberg, J., Johnson, T.L., Patrick, M., Abendroth, J., Hol, W.G.J., and Sandkvist, M. 2007. Synergistic stimulation of EpsE ATP hydrolysis by EpsL and acidic phospholipids. EMBO J., 26:19-27.