Functional study of Toxoplasma gondii small heat shock protein 20

DE NAPOLI, MG; COCERES, VM; ARRIZABALAGA, G; MORENO,SN; ANGEL, SO; CORVI, MM

Puerto Varas

Congreso; XII PABMB Congress; 2013

Sociedad Bioquíimica y Biología Molecular de Chile

Toxoplasma gondii is a protozoan parasite which belongs to the phylum Apicomplexa. It is known that synthesis of small heat sock proteins (sHSP) can be triggered under conditions of stress. Our laboratory has studied T. gondii HSP20 which localizes to the inner membrane complex (IMC). This localization is achieved by N-terminal palmitoylation. Experiments with the palmitoylation inhibitor 2-bromopalmitate show changes in TgHSP20 localization from the parasite?s pellicle to the cytosol. Similar results can be obtained with a non-palmitoylable TgHSP20 version. In addition, we generated a Tghsp20 gene deletion (TgHSP20-KO) strain to address TgHSP20 function. TgHSP20 showed to be dispensable for parasite survival and these parasites showed no growth defect. However, the TgHSP20-KO strain showed a mild invasion phenotype at low temperature. Additionally, the TgHSP20-KO strain displayed a lower invasion rate than the parental strain after treatment with agents that affect membrane fluidity. This suggests that TgHSP20 might be involved in maintenance of membrane fluidity and that this condition is necessary for invasion. Further characterization of the phenotype of this mutant under a variety of environmental stress conditions is ongoing.