Systematic analysis of essential parasite genes linked to invasion of the host cell in Toxoplasma gondii.

Apicomplexan parasites evolved unique organelles (micronemes, rhoptries and IMC) that enable invasion of the host cell. Interestingly, these organelles are linked to the secretory system. Therefore, systematic functional characterisation of factors believed to play a role in vesicular traffic, like Rab-GTPases, motor proteins, dynamins or SNAREs, will lead to novel insights as to how apicomplexans regulate biogenesis, maintenance and regulated secretion of these organelles. We previously demo nstrated that parasites deficient in these processes are unable to invade and we established image based approaches to automatically identify and characterise these mutants. We now want to expand our systematic, functional characterisation of genes of interest (GOIs) linked to these processes, using two complementary approaches: targeted mutagenesis and a random mutagenesis screen to identify novel factors that cannot be identified bioinformatically. The key goals are: I) Functional characte risation of GOIs 1) Determination of mechanisms of vesicular traffic and regulated secretion involving known GOIs 2) By screening of a new library of random parasite mutants, identification of novel mutants affected in host cell invasion 3) Functional, mechanistic characterisation of confirmed novel GOIs II) Long term goals 1) Establishment of an open access database for characterised mutants 2) Screening for chemical inhibitors for validated GOIs