Keep Up the Good (Bench) Work!

Professor Silvia Moreno studies toxoplasmosis, one of the most common parasitic infections in the world, caused by Toxoplasma gondii. About one-third of the human population is chronically infected with T. gondii cysts, the dormant form of the parasite. Although most immunocompetent infected individuals remain asymptomatic throughout life, serious complications such as loss of vision, mother-to-fetus transmission, and fatal cases can occur. The drugs currently available to treat toxoplasmosis are unable to clear the cyst form of the parasite and have severe side effects like bone marrow suppression and liver toxicity. Silvia has studied parasite metabolism for more than 20 years and has been at the University of Georgia since 2005. Her goal is to uncover unique aspects of parasite metabolism that can be targeted for designing more effective, less toxic drugs against T. gondii. In this short interview, Silvia highlights the importance of staying true to one's identity and of learning to say 'no', and advises young researchers to not stay away from the bench.

N-terminal palmitoylation is required for Toxoplasma gondii HSP20 inner membrane complex localization.

Toxoplasma gondii is an obligate intracellular parasite and the causative agent of toxoplasmosis. Protein palmitoylation is known to play roles in signal transduction and in enhancing the hydrophobicity of proteins thus contributing to their membrane association. Global inhibition of protein palmitoylation has been shown to affect T. gondii physiology and invasion of the host cell. However, the proteins affected by this modification have been understudied. This paper shows that the small heat shock protein 20 from T. gondii (TgHSP20) is synthesized as a mature protein in the cytosol and is palmitoylated in three cysteine residues. However, its localization at the inner membrane complex (IMC) is dependent only on N-terminal palmitoylation. Absence or incomplete N-terminal palmitoylation causes TgHSP20 to partially accumulate in a membranous structure. Interestingly, TgHSP20 palmitoylation is not responsible for its interaction with the daughter cells IMCs. Together, our data describe the importance of palmitoylation in protein targeting to the IMC in T. gondii.