The co-chaperone SGT of Leishmania donovani is essential for the parasite's viability
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Molecular chaperone proteins play a pivotal role in the protozoan parasite Leishmania donovani, controlling cell fate and ensuring intracellular survival. In higher eukaryotes, the so-called co-chaperone proteins are required for client protein recognition and proper function of chaperones, among them the small glutamine-rich tetratricopeptide repeat proteins (SGT) which interact with both HSP70 and HSP90 chaperones. An atypical SGT homolog is found in the L. donovani genome, encoding a protein lacking the C-terminal glutamine-rich region, normally typical for SGT family members. The gene is expressed constitutively during the life cycle and is essential for survival and/or growth of the parasites. LdSGT forms large, stable complexes that also include another putative co-chaperone, HSC70 interacting protein (HIP). The gene product forms cytoplasmic clusters, matching the subcellular distribution of HIP and partly that of the major cytoplasmic chaperones, HSP70 and HSP90, reflecting a direct molecular interaction with both chaperones.
KeywordsLeishmania Tetratricopeptide repeat SGT Foldosome complex Co-chaperone
The authors acknowledge the technical assistance of Dorothea Zander, Manfred Krömer (died 2009), and Stefanie Pflichtbeil. Doreen Gutzke created the pTL.v3-eGFP plasmid. M.C. was a fellow of the Vereinigung der Freunde des Tropeninstituts e.V., Hamburg. We also thank Wai-Lok Yau for the helpful suggestions.
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