associate professor of biology
Field of Interest
Genetic approaches towards the cell biology of Toxoplasma gondii.
The protozoan parasite Toxoplasma gondii is a member of the phylum Apicomplexa and can cause severe disease in humans. This parasite is easily grown and manipulated in vitro and has in recent years developed as a safe and versatile model for other apicomplexan parasites (e.g. malaria). We are using and developing forward, reverse and functional genetic tools using enzymatic as well as fluorescent protein reporter assays in combination with cell sorting and fluorescence microscopy to learn more about the parasite’s cell biology.
Parasite replication is conserved, yet are variations on a theme in different apicomplexan parasites. Toxoplasma divides by an internal budding process called endodyogeny where two daughters are being assembled inside the mother, which is significantly different from mammalian cell division. The parasite’s cytoskeleton, consisting of microtubules as well as a membrane skeleton in combination with intermediate protein filaments (the inner membrane complex or IMC) serves as a scaffold for daughter assembly. Recently, we identified several components that act in the cytoskeleton assembly as well as daughter formation which are currently being characterized in detail.
Host cell invasion is an essential step in the life cycle of Apicomplexa and identifying essential steps and/or molecules in the process would provide attractive potential therapeutic targets. To identify key molecules in invasion, a set of conditional parasite invasion mutants has been generated through chemical as well as insertional (conditional) mutagenesis. Mutants are being analyzed through a set of cell biological assays while at the same time the mutated genes are being identified using cosmid library complementations as well as plasmid rescues.
Brown, K.M. E. Suvorova, A. Farrell, A. McLain, A. Dittmar, G.B. Wiley, G.T. Marth, P.M. Gaffney, M.-J. Gubbels, M. White, and I. Blader. 2014. Forward genetic screening identifies a small molecule that blocks Toxoplasma growth by inhibiting both host- and parasite-encoded kinases. PLoS Path. 10(6):e1004180.
Farrell, A., B.I. Coleman, B. Benenati, K.M. Brown, I. Blader, G.T. Marth, and M.-J. Gubbels. 2014. Whole genome profiling of spontaneous and chemical mutagenesis induced mutations in Toxoplasma gondii. BMC Genomics. 15: 354.
Gubbels, M.-J., and Morrissette, N. 2013. The Cytoskeleton: structures and motility (chapter 13). In: Toxoplasma gondii: The Model Apicomplexan, 2nd edition. Eds.: L.M. Weiss and K. Kim. Elsevier Academic Press. ISBN: 9780123964816.
Farrell, M., and M.-J. Gubbels. 2014. The Toxoplasma gondii kinetochore is required for centrosome association with the centrocone (spindle pole). Cell. Microbiol. 16: 78-94.
Morlon-Guyot, J., L. Berry, C.-T. Chen, M.-J. Gubbels, M. Lebrun, and W. Daher. 2014. The Toxoplasma gondii Calcium Dependent Protein Kinase 7 is involved in early steps of parasite division and is crucial for parasite survival. Cell. Microbiol. 16: 95-114.
Yang, N., A. Farrell, W. Niedelman, M. Melo, D. Lu, L. Julien, G.T. Marth, M.-J. Gubbels, J.P.J. Saeij. 2013 Genetic basis for phenotypic differences between different Toxoplasma gondii type I strains. BMC Genomics. 14:467.
Chen, C.-T. and M.-J. Gubbels. 2013. The Toxoplasma gondii centrosome is the platform for internal daughter budding as revealed by a Nek1 kinase mutant. Journal of Cell Science. 126:3344-3355.
Lorestani, A., F.D. Ivey, S. Thirugnanam, M.A. Busby, G.T. Marth, I. Cheeseman, and M.-J. Gubbels. 2012. Targeted proteomic dissection of Toxoplasma cytoskeleton sub-compartments using MORN1. Cytoskeleton. 69:1069-1085.
Gubbels, M.-J. and M.T. Durasingh. 2012. Evolution of apicomplexan secretory organelles. Int. J. Parasitol. 42:1071-1081 (invited review). Highlighted as a Feature Article on the Malaria Nexus website.
Bushkin, G.G., P. Magnelli, E. Motari, M.-J. Gubbels, J.P. Dubey, K. Miska, E. Bullitt, C.E. Costello, P.W. Robbins, and J. Samuelson. 2012. β-1,3-glucan, a druggable target, is part of a trabecular scaffold in inner layer of the oocyst wall of Toxoplasma and Eimeria. mBio. 3(5). pii: e00258-12.
Anderson-White, B.R., J.R. Beck, C.-T. Chen, M. Meissner, P.J. Bradley, and M.-J. Gubbels. 2012. Cytoskeleton assembly in Toxoplasma gondii cell division. Int. Rev. Cell Mol. Biol. 298:1-31.
Fung, C., J.R. Beck, S.D. Robertson, M.-J. Gubbels, and P.J. Bradley. Toxoplasma ISP4 is a central IMC sub-compartment protein whose localization depends on palmitoylation but not myristoylation. Mol. Biochem Parasitol. 184:99-108.
Szatanek, T., B.R. Anderson-White, M. White, J. Saeij, and M.-J. Gubbels. 2012. Cactin is essential for G1 progression in Toxoplasma gondii. Mol. Micro. 84:566-577.
Coleman, B.I., and M.-J. Gubbels. 2012. A genetic screen to isolate Toxoplasma gondii host cell egress mutants. J. Vis. Exp. 60:e3807.
Farrell, A. S. Thirugnanam, A. Lorestani, J.D. Dvorin, K.P. Eidell, B.R. Anderson-White, D.J.P. Ferguson, M.T. Duraisingh, G.T. Marth, and M.-J. Gubbels. 2012. A DOC2 protein identified by mutational profiling is essential for apicomplexan parasite exocytosis. Science. 335:218-221.
Jammallo*, L., K. Eidell*, P.H. Davis, F.J. Dufort, C. Cronin, S. Thirugnanam, T.C. Chiles, D.S. Roos, and M.-J. Gubbels. 2011. An insertional trap for conditional gene expression in Toxoplasma gondii: identification of TAF250 as an essential gene. Mol. Biochem. Parasitol. 175:133-143. (*equal contribution).
Anderson-White, B.R., Ivey, F.D., Cheng, K. K., Szatanek, T., Lorestani, A., Beckers, C.J., Ferguson, D.J.P., Sahoo, N., and Gubbels, M.-J. 2010. A family of intermediate filament-like proteins is sequentially assembled into the cytoskeletal scaffold of Toxoplasma gondii. Cellular Microbiology 13:18-31.
Lorestani, A., L. Sheiner, K. Yang, S.D. Robertson, N. Sahoo, C.F. Brooks, D.P.J. Ferguson, B. Striepen, and M.-J. Gubbels. 2010. A Toxoplasma MORN1 null mutant is defective in basal complex assembly and apicoplast division. PLoS ONE. 5:e12302.
Eidell, K., Burke, T., and Gubbels, M.-J. 2010. Development of a screen to dissect Toxoplasma gondii egress. Molecular and Biochemical Parasitology 171(2): 97–10.
Wilson, D.C., Grotenbreg, G.M., Liu, K.N., Zhao, Y., Frickel, E.-M., Gubbels, M.-J., Ploegh, H.L., and Yap, G.S. 2010. Differential regulation of effector- and central-memory responses to Toxoplasma gondii infection by IL-12 revealed by tracking of Tgd057-specific CD8+ T cells. PLoS Pathogens 6(3): e1000815.
Bushkin, G.G., Ratner, D.M., Cui, J., Banerjee, S., Duraisingh, M.T., Jennings, C.V., Dvorin, J.D., Gubbels, M.-J., Robertson, S.D., Steffen, M., O’Keefe, B.R., Robbins, P.W., and Samuelson, J. 2010. Evidence for Darwinian selection against asparagine-linked glycans of Plasmodium and Toxoplasma. Eukaryotic Cell 9: 228–241.
Frickel, E.M., Sahoo, N., Hopp, J., Gubbels, M.-J., Craver, M.P., Knoll, L.J., Ploegh, H., and Grotebreg, G. 2008. Parasite stage-specific recognition of endogenous Toxoplasma gondii epitopes by CD8+T cells. The Journal of Infectious Diseases 198: 1625–1633.
Gubbels, M.-J., White, M., and Szatanek, T. 2008. The cell cycle and Toxoplasma gondii cell division: tightly knit or loosely stitched? International Journal for Parasitology 38: 1343–1358 (Invited Review).
Muskavitch, M., Barteneva, N., and Gubbels, M.-J. 2008. Chemogenomics and parasitology: small molecules and cell-based assays to study infectious processes. Combinatorial Chemistry & High Throughput Screening 11: 629–649 (Invited Review).
Ferguson, D.J.P., Sahoo, N., Pinches, R.A., Bumstead, J.M., Tomley, F.M., and Gubbels, M.-J. 2008. MORN1 has a conserved role in asexual and sexual development across the Apicomplexa. Eukaryotic Cell 7: 698–711. Featured in ASM Microbe, June 2008.
Gubbels, M.-J., Brooks, C.F., Muthalagi, M., Szatanek, T., Flynn, J., Parrot, B., Striepen, B., and White, M.W. 2008. Forward genetic analysis of the apicomplexan cell and division cycle in Toxoplasma gondii. PLoS Pathogens 4(2): e36 (0001–0015) (Editor’s Pick).
Frickel, E.-M., Quesada, V., Muething, L., Gubbels, M.-J., Spooner, E., Ploegh, H., and Artavanis-Tsakonas, K. 2007. UCHL3 retains dual specificity for ubiquitin and Nedd8 throughout evolution. Cellular Microbiology 6: 1601–1610.
Gubbels, M.J., Mazumdar, J., van Dooren, G., and Striepen, B. 2006. Manipulating the Toxoplasma genome. In "The biology of Toxoplasma gondii." Soldati, D., and Ajioka, J. (Eds.). Horizon Scientific Pres, Norwich, UK.
Gubbels, M.-J., Vaishnava, S., Boot, N., Dubremetz, J.-F., and Striepen, B. 2006. A MORN-repeat protein is a dynamic component of the cell division apparatus of the parasite Toxoplasma gondii. Journal of Cell Science 119: 2236–2245.