Inverted topology of the Toxoplasma gondii ROP5 rhoptry protein provides new insights into the association of the ROP2 protein family with the parasitophorous vacuole membrane
Article first published online: 31 JUL 2006
Volume 9, Issue 1, pages 54–64, January 2007
How to Cite
El Hajj, H., Lebrun, M., Fourmaux, M. N., Vial, H. and Dubremetz, J. F. (2007), Inverted topology of the Toxoplasma gondii ROP5 rhoptry protein provides new insights into the association of the ROP2 protein family with the parasitophorous vacuole membrane. Cellular Microbiology, 9: 54–64. doi: 10.1111/j.1462-5822.2006.00767.x
- Issue published online: 31 JUL 2006
- Article first published online: 31 JUL 2006
- Received 18 January, 2006; revised 2 May, 2006; accepted 24 May, 2006.
Toxoplasma gondii, as many intracellular parasites, is separated from the cytosol of its host cell by a parasitophorous vacuole membrane (PVM). This vacuole forms during host cell invasion and parasite apical organelles named rhoptries discharge proteins that associate with its membrane during this process. We report here the characterization of the rhoptry protein ROP5, which is a new member of the ROP2 family. Contrasting with what is known for other ROP2 family proteins, ROP5 is not processed during trafficking to rhoptries. We show here that ROP5 is secreted during invasion and associates with the PVM. Using differential permeabilization of infected cells, we have shown that ROP5 exposes its C-terminus towards the host cell cytoplasm, which corresponds to a reverse topology compared with ROP2 and ROP4. Taken together with recent modelling data suggesting that the C-terminal hydrophobic domain hitherto described as transmembrane may correspond to a hydrophobic helix buried in the catalytic domain of kinase-related proteins, these findings call for a reappraisal of the current view of ROP2 family proteins association with the PVM.