The small heat shock protein 20 is palmitoylated in Toxoplasma gondii

DE NAPOLI M.G, DE MIGUEL N, ANGEL S.O. AND CORVI M.M

Rosario, Argentina

Congreso; XXIII Reunión Cientifica Anual. Sociedad Argentina de Protozoología. Rosario. Argentina; 2008

The protozoan Toxoplasma gondii is an obligate intracellular parasite that is able to infect most nucleated cells of warm-blooded animals. An important structure of this parasite is the pellicle, which consists of the plasma membrane and of the inner membrane complex (IMC). The IMC plays a key role as an anchor for the gliding apparatus of the parasite, and as such in its motility. TgHSP20 is a stripe-arranged chaperone localized to the outer leaflet of the IMC. TgHSP20 association to this specialized structure is quite striking since the protein does not contain any hydrophobic region or transmembrane domains. Compared alignment of HSP20 aminoacidic sequences from different apicomplexa parasites revealed a set of cisteines that are conserved among them. Interestingly, these conserved cisteine residues are predicted to be palmitoylated by “in silico” analysis. Metabolic labeling of extracellular T. gondii tachyzoites with 3H-palmitic acid confirmed that HSP20 can be palmitoylated “in vivo”. In order to reveal the identity of the acceptor(s) residue(s) on the protein and the importance of TgHSP20 palmitoylation for T. gondii physiology, several studies are being carried out and will be discussed.