Professor Markus Meisner, Institute of Infection, Immunity and Inflammation, University of Glasgow
Tuesday 25th October, 1.00 p.m., Stacey Lecture Theatre 1
Apicomplexans, such as Toxoplasma gondii or Plasmodium falciparum, are obligate intracellular parasites with a complex life cycle. In order to invade the host cell these unicellular organisms evolved specialised organelles, an elaborate cytoskeleton and a unique form of movement, called gliding motility. The secretory organelles (micronemes and rhoptries) are secreted in a highly regulated, stepwise process and contain multiple virulence factors required for invasion. The current model for gliding motility predicts that micronemal proteins transfer the force produced by the actin-myosin-system of the parasite to the surface, resulting in forward movement. However, this linear motor model cannot be easily reconciled with recent data that indicate alternative motility mechanisms. Biophysical and reverse genetic studies now implicate a novel role of the acto-myosin-system in surface attachment, rather than force generation. Here I will discuss our attempts to dissect the invasion machinery, focusing on the formation of the secretory organelles and their role during invasion. Furthermore the current alternative motility mechanisms will be discussed in light of novel data for the acto-myosin-system and other critical components of this fascinating system.