An endocytic-secretory cycle participates in < i > Toxoplasma gondii < /i > in motility

by Simon Gras, Elena Jimenez-Ruiz, Christen M. Klinger, Katja Schneider, Andreas Klingl, Leandro Lemgruber, Markus Meissner Apicomplexan parasites invade host cells in an active process involving their ability to move by gliding motility. While the acto-myosin system of the parasite plays a crucial role in the formation and release of attachment sites during this process, there are still open questions regarding the in volvement of other mechanisms in parasite motility. In many eukaryotes, a secretory-endocytic cycle leads to the recycling of receptors (integrins), necessary to form attachment sites, regulation of surface area during motility, and generation of retrograde membrane flow. Here, we demonstrate that e ndocytosis operates during gliding motility inToxoplasma gondii and appears to be crucial for the establishment of retrograde membrane flow, because inhibition of endocytosis blocks retrograde flow and motility. We demonstrate that extracellular parasites can efficiently incorporate exogenous material, such as labelled phospholipids, nanogold particles (NGPs), antibodies, and Concanavalin A (ConA). Using labelled phospholipids, we observed that the endocytic and secretory pathways of the parasite converge, and endocytosed lipids are subsequently secreted, demonstrating the operation of an endocytic-secretory cycle. Together our data consolidate previous findings, and we propose an additional model, working in parallel to the acto-myosin motor, that reconciles paras...
Source: PLoS Biology: Archived Table of Contents - Category: Biology Authors: Source Type: research