Toxoplasma: Meißner
AG Meißner (from left): Manuela Breinich (PhD student), Carolina Agop-Nersesian (PhD student), Henning Keßler (PhD student), Katrin Klaus (PhD student), Markus Meißner (Group leader), Manuel Rauch (BTA)
Research Interests
Like all organisms of the phylum Apicomplexa, Toxoplasma gondii is an obligate intracellular parasite with a complicated life cycle that includes transmission and differentiation within and between hosts. Whereas the final host are Felidae (cats), where the sexual life cycle takes place, the asexual life cycle occurs in every warm blooded animal (including humans). Although in general a mild infection, T.gondii, develops into persistent stages, which remain life-long within the host (mainly in the brain). The main medical importance of this parasite is infection of pregnant women, which can lead to miscarriage and developmental defects of the embryo as well as the reactivation of persistent stages in immunocompromised patients (AIDS).
Although a fascinating pathogen by its own, T.gondii shares many features with other Apicomplexa such as Plasmodium spec., the causative agent of malaria. Since this parasite can be easily genetically manipulated and propagated easily in vitro it recommends itself as a model organism to study conserved mechanisms of apicomplexan parasites.
In the absence of host cell phagocytosis apicomplexan parasites actively invade the host cell by their ability to move by gliding motility a unique form of movement only found in Apicomplexa. Since invasion of the host cell is a critical step during the asexual life cycle we are interested in essential factors involved in this process. Using a recently developed tetracycline inducible system it is now possible to characterise essential genes in this parasite using forward and reverse genetic strategies.
Another interest of our group is to understand how T.gondii regulates its genes. Although many stage specific genes have been identified our knowledge on the mechanisms of gene regulation in apicomplexa is still embryonic. In order to learn more about trans-acting and cis-acting elements we employ a genetic screen based on random insertion mutagenesis to identify gene regulatory proteins and subsequently their target genes.
Contact:
AG Meißner
Im Neuenheimer Feld 326
2nd floor, rooms 202 and 203
69120 Heidelberg
Germany
E-Mail: Markus.Meissner@med.uni-heidelberg.de
Publications
van Dooren GG, Reiff SB, Tomova C, Meissner M, Humbel BM, Striepen B. (2009), A Novel Dynamin-Related Protein Has Been Recruited for Apicoplast Fission in Toxoplasma gondii. Current Biology
Breinich MS, Ferguson DJ, Foth BJ, van Dooren GG, Lebrun M, Quon DV, Striepen B, Bradley PJ, Frischknecht F, Carruthers VB, Meissner M. (2009), A Dynamin Is Required for the Biogenesis of Secretory Organelles in Toxoplasma gondii. Current Biology
Agop-Nersesian C, Naissant B, Ben Rached F, Rauch M, Kretzschmar A, Thiberge S, Menard R, Ferguson DJ, Meissner M, Langsley G. (2009), Rab11A-controlled assembly of the inner membrane complex is required for completion of apicomplexan cytokinesis.PLoS Pathogen, 5(1)
Agop-Nersesian C, Pfahler, J., Lanzer, M. and Meissner, M. (2008), Functional expression of Ribozymes in Apicomplexa: Towards exogenous control of gene expression by inducible RNA-cleavage. International Journal for Parasitology 38(6):673-81 (pubmed),
Kessler, H., Herm-Götz, A., Hegge, S., Rauch, M., Soldati, D., Frischknecht, F. and Meissner, M. (2008). Microneme protein 8: A new essential invasion factor in Toxoplasma gondii. Journal of Cell Science, 121, 947-56 (pubmed)
Herm-Götz,A.*, Agop-Nersesian*, C., Münter*, S., Grimley,J.S., Wandless, T.J., Frischknecht, F. and Meissner, M. (2007). Rapid control of protein levels in the apicomplexan parasite Toxoplasma gondii. Nature Methods 4,1003-5 (pubmed)
Cyrklaff, M., Kudryashev, M., Leis, A., Leonard, K., Baumeister, W., Menard, R., Meissner, M. and Frischknecht, F. (2007). Cryoelectron tomography reveals periodic material at the inner side of subpellicular microtubules in apicomplexan parasites. J Exp Med 204, 1281-7. (pubmed)
Mital, J., Meissner, M., Soldati, D. and Ward, G. E. (2005). Conditional expression of Toxoplasma gondii apical membrane antigen-1 (TgAMA1) demonstrates that TgAMA1 plays a critical role in host cell invasion. Mol Biol Cell 16, 4341-9. (pubmed)
Meissner, M.*, Krejany, E.*, Gilson, P. R., de Koning-Ward, T. F., Soldati, D. and Crabb, B. S. (2005). Tetracycline analogue-regulated transgene expression in Plasmodium falciparum blood stages using Toxoplasma gondii transactivators. Proc Natl Acad Sci U S A 102, 2980-5. (pubmed)
Reviewed Articles
Langsley, G., van Noort, V., Carret, C., Meissner, M., de Villiers, E.P., Bishop, R., Pain A. (2008). Comparative genomics of the Rab protein family in Apicomplexan parasites. Microbes Infect. 10(5), 462-70. (pubmed)
Meissner, M., Agop-Nersesian, C. and Sullivan, W. J., Jr. (2007). Molecular tools for analysis of gene function in parasitic microorganisms. Appl Microbiol Biotechnol 75, 963-75. (pubmed)
Meissner, M., Breinich, M. S., Gilson, P. R. and Crabb, B. S. (2007). Molecular genetic tools in Toxoplasma and Plasmodium: achievements and future needs. Curr Opin Microbiol 10, 349-56. (pubmed)
Meissner, M. and Soldati, D. (2005). The transcription machinery and the molecular toolbox to control gene expression in Toxoplasma gondii and other protozoan parasites. Microbes Infect 7, 1376-84. (pubmed)
Soldati, D. and Meissner, M. (2004). Toxoplasma as a novel system for motility. Current Opinion in Cell Biology 16, 32-40. (pubmed)
Book Chapters
Dominique Soldati and Markus Meissner. (2004). Toxoplasma gondii a Model Organism for the Apicomplexans?. In: Malaria Parasites: Genomes and Molecular Biology. Edited by: A.P. Waters and C.J. Janse, Caister Academic Press, Wymondham, Norfolk, UK. ( ISBN: 0-9542464-6-2). pp. 135-165.
