Phosphoproteome dynamics reveal heat-shock protein complexes specific to the Leishmania donovani infectious stage

Abstract

Leishmania is exposed to a sudden increase in environmental temperature during the infectious cycle that triggers stage differentiation and adapts the parasite phenotype to intracellular survival in the mammalian host. The absence of classical promoter-dependent mechanisms of gene regulation and constitutive expression of most of the heat-shock proteins (HSPs) in these human pathogens raise important unresolved questions as to regulation of the heat-shock response and stage-specific functions of Leishmania HSPs. Here we used a gel-based quantitative approach to assess the Leishmania donovani phosphoproteome and revealed that 38% of the proteins showed significant stage-specific differences, with a strong focus of amastigote-specific phosphoproteins on chaperone function. We identified STI1/HOP-containing chaperone complexes that interact with ribosomal client proteins in an amastigote-specific manner. Genetic analysis of STI1/HOP phosphorylation sites in conditional sti1

Pharmacological Assessment Defines Leishmania donovani Casein Kinase 1 as a Drug Target and Reveals Important Functions in Parasite Viability and Intracellular Infection

“…However, many aspects of this protein remain unknown, such as its implication in intracellular amastigote survival, as the only available data on the impact of CK1 inhibition on parasite survival were obtained on cultured promastigotes. Yet, proteomics and phosphoproteomics studies revealed important differences in stage-specific protein expression and protein phosphorylation between promastigotes and amastigotes (21)(22)(23). As a consequence, pharmacological data obtained for CK1.2 in promastigotes cannot be directly extrapolated to axenic amastigotes or intracellular parasites.…”

Contribution of proteomics of Leishmania spp. to the understanding of differentiation, drug resistance mechanisms, vaccine and drug development

“…This idea is currently pursued by the Leishdrug consortium. Overall, the data suggest that PTMs are involved in the stress response in Leishmania 37,38 .…”

“…Further differences in the phosphorylation were revealed by comparison of L. donovani promastioges and axenic amastigotes of IMAC enriched phospoproteome by 2D-differential gel electrophoresis 37 . In total 813 protein spots were detected with more than 700 present in three biological repeats.…”

“…Amastigote proteins increasing in abundance/phosphorylation were almost exclusively protein chaperones e.g. HSP90/HSP83, HSP70 family members and stress induced protein STI1 37 . Phosphorylation of HSPs might be involved in the regulation of HSP function in the parasite.…”

“…The complex might be involved in the control of protein translation 37 or simply provide a platform of translation and formation of correctly folded proteins. Three phosphorylation sites of STI were identified (residues S15, T217 and S481) with residues S15 and S481 required for L. donovani viability in culture highlighting the significance of chaperone phosphorylation in the parasite 37 .…”