INVESTIGADORES
COCERES Veronica Mabel
congresos y reuniones científicas
Título:
Toxoplasma gondii HSP20 depends on palmitoylation for proper pellicle localization and plays a role in invasion and gliding?
Autor/es:
DE NAPOLI MG; COCERES VM; ARRIZABALAGA G; MORENO S; ANGEL SO ; CORVI M
Lugar:
Woods Hole
Reunión:
Congreso; International Congress; 2012
Resumen:
Toxoplasma gondii is a protozoan parasite, which belongs to the phylum Apicomplexa. The parasite suffers different types of stresses in order to successfully complete its lytic cycle. It is known that synthesis of small heat sock proteins (sHSP) can be triggered under conditions of stress. This group of sHSP is characterized by having a molecular mass ranging between 15 and 42 kDa. These proteins are able to partially interact with unfolded proteins in order to prevent aggregation in response of cellular stress, but also modulate cytoskeleton filaments and membrane fluidity, among other functions. Our laboratory has studied the T. gondii TgHSP20 and found that it is a functional chaperone localized to the inner membrane complex (IMC). Here we demonstrate that TgHSP20 is palmitoylated at 3 cysteine residues. Experiments with the palmitoylation inhibitor 2-bromopalmitate showed that HSP20 changes its localization from the parasite?s pellicle to the cytosol, indicating that palmitoylation plays a role in its localization. Using site directed mutagenesis, we generated over-expressing non-palmitoylated HSP20 versions. TgHSP20-C3,4,160S, showed cytosolic localization, however, the localization at IMC daughter cells showed not to be altered. These results suggest that a mechanism different than palmitoylation targets the protein to the nascent IMC. We generated an HSP20 gene deletion strain. These parasites show a growth defect in growth competition assays and also a mild invasion phenotype. Further characterization of the phenotype of this mutant under a variety of environmental stress conditions is ongoing.