Conformational Plasticity of Centrin 1 from Toxoplasma gondii in Binding to the Centrosomal Protein SFI1

Bombardi, Luca; Favretto, Filippo; Pedretti, Marco; Conter, Carolina; Dominici, Paola; Astegno, Alessandra

doi:10.3390/biom12081115

Cited by 4 publications

(2 citation statements)

References 55 publications

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“…Centrins are a group of calcium binding proteins that are associated with virtually all eukaryotic centrosomes and have been implicated in their duplication [29,39,40]. A key interaction partner of centrin in most organisms, including the apicomplexan Toxoplasma gondii, is Sfi1 and the presence of an orthologue has been hypothesized for P. falciparum [30,[41][42][43][44]. Shortly after centrin recruitment the hemispindle collapses, the centrin signal duplicates and the mitotic spindle assembles [35].…”

Section: Introductionmentioning

confidence: 99%

An Sfi1-like centrin-interacting centriolar plaque protein affects nuclear microtubule homeostasis

et al. 2023

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Malaria-causing parasites achieve rapid proliferation in human blood through multiple rounds of asynchronous nuclear division followed by daughter cell formation. Nuclear divisions critically depend on the centriolar plaque, which organizes intranuclear spindle microtubules. The centriolar plaque consists of an extranuclear compartment, which is connected via a nuclear pore-like structure to a chromatin-free intranuclear compartment. Composition and function of this non-canonical centrosome remain largely elusive. Centrins, which reside in the extranuclear part, are among the very few centrosomal proteins conserved in Plasmodium falciparum. Here we identify a novel centrin-interacting centriolar plaque protein. Conditional knock down of this Sfi1-like protein (PfSlp) caused a growth delay in blood stages, which correlated with a reduced number of daughter cells. Surprisingly, intranuclear tubulin abundance was significantly increased, which raises the hypothesis that the centriolar plaque might be implicated in regulating tubulin levels. Disruption of tubulin homeostasis caused excess microtubules and aberrant mitotic spindles. Time-lapse microscopy revealed that this prevented or delayed mitotic spindle extension but did not significantly interfere with DNA replication. Our study thereby identifies a novel extranuclear centriolar plaque factor and establishes a functional link to the intranuclear compartment of this divergent eukaryotic centrosome.

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Section: Introductionmentioning

confidence: 99%

An Sfi1-like centrin-interacting centriolar plaque protein affects nuclear microtubule homeostasis

et al. 2023

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“…ITC experiments were performed on a VP-ITC instrument from MicroCal (Northampton, MA) as described elsewhere. , CsA at 8–20 μM was titrated with 2–3 μL of 66–400 μM Cyp solution at 20 °C (13–19 total injections) in the ITC measuring buffer (50 mM Hepes, pH 8.0; 100 mM NaCl) supplemented with 0.4% ethanol (v/v) keeping a time gap of 150 s between injections. All buffers were filtered (0.22 μm) and degassed immediately before use.…”

Section: Methodsmentioning

confidence: 99%

Structural Basis for Cyclosporin Isoform-Specific Inhibition of Cyclophilins from Toxoplasma gondii

et al. 2023

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Cyclosporin (CsA) has antiparasite activity against the human pathogen Toxoplasma gondii. A possible mechanism of action involves CsA binding to T. gondii cyclophilins, although much remains to be understood. Herein, we characterize the functional and structural properties of a conserved (TgCyp23) and a more divergent (TgCyp18.4) cyclophilin isoform from T. gondii. While TgCyp23 is a highly active cis–trans-prolyl isomerase (PPIase) and binds CsA with nanomolar affinity, TgCyp18.4 shows low PPIase activity and is significantly less sensitive to CsA inhibition. The crystal structure of the TgCyp23:CsA complex was solved at the atomic resolution showing the molecular details of CsA recognition by the protein. Computational and structural studies revealed relevant differences at the CsA-binding site between TgCyp18.4 and TgCyp23, suggesting that the two cyclophilins might have distinct functions in the parasite. These studies highlight the extensive diversification of TgCyps and pave the way for antiparasite interventions based on selective targeting of cyclophilins.

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Evaluating the potential of non‐immunosuppressive cyclosporin analogs for targeting Toxoplasma gondii cyclophilin: Insights from structural studies

Favretto,

Jiménez‐Faraco,

Catucci

et al. 2024

Protein Science

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Toxoplasmosis persists as a prevalent disease, facing challenges from parasite resistance and treatment side effects. Consequently, identifying new drugs by exploring novel protein targets is essential for effective intervention. Cyclosporin A (CsA) possesses antiparasitic activity against Toxoplasma gondii, with cyclophilins identified as possible targets. However, CsA immunosuppressive nature hinders its use as an antitoxoplasmosis agent. Here, we evaluate the potential of three CsA derivatives devoid of immunosuppressive activity, namely, NIM811, Alisporivir, and dihydrocyclosporin A to target a previously characterized cyclophilin from Toxoplasma gondii (TgCyp23). We determined the X‐ray crystal structures of TgCyp23 in complex with the three analogs and elucidated their binding and inhibitory properties. The high resolution of the structures revealed the precise positioning of ligands within the TgCyp23 binding site and the details of protein–ligand interactions. A comparison with the established ternary structure involving calcineurin indicates that substitutions at position 4 in CsA derivatives prevent calcineurin binding. This finding provides a molecular explanation for why CsA analogs can target Toxoplasma cyclophilins without compromising the human immune response.

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Conformational Plasticity of Centrin 1 from Toxoplasma gondii in Binding to the Centrosomal Protein SFI1

Cited by 4 publications

References 55 publications

An Sfi1-like centrin-interacting centriolar plaque protein affects nuclear microtubule homeostasis

An Sfi1-like centrin-interacting centriolar plaque protein affects nuclear microtubule homeostasis

Structural Basis for Cyclosporin Isoform-Specific Inhibition of Cyclophilins from Toxoplasma gondii

Evaluating the potential of non‐immunosuppressive cyclosporin analogs for targeting Toxoplasma gondii cyclophilin: Insights from structural studies

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