Mass spectrometry identification of partners of the Toxoplasma gondii HCF101 protein

Toxoplasma gondii is a parasitic protist that is the agent of toxoplasmosis. It is capable of infecting a wide variety of vertebrates, including humans. The infection is mainly asymptomatic in immunocompetent patients, but in case of immunosuppression or for the congenital form of toxoplasmosis it can lead to severe pathologies with a possible fatal outcome. Like for other eukaryotes, many key cellular functions in T. gondii involve proteins containing an iron-sulfur cluster as a cofactor. Cytosolic and nuclear iron-sulfur proteins depend on a specific pathway for assembling their iron-sulfur cofactor. We have investigated the T. gondii homolog of the HCF101 protein, initially characterized in plants as a chloroplast-based iron-sulfur transfer protein, by co-immunoprecipitating associated protein partners and identifying them by mass spectrometry. It confirmed that T. gondii HCF101 is not involved in plastid-based iron-sulfur metabolism, but in the biogenesis of cytosolic and nuclear iron-sulfur proteins instead.