Selenoproteins of African trypanosomes are dispensable for parasite survival in a mammalian host

Bonilla, Mariana; Krull, Erika; Irigoı́n, Florencia; Salinas, Gustavo; Comini, Marcelo A.

doi:10.1016/j.molbiopara.2016.03.002

Cited by 15 publications

(6 citation statements)

References 43 publications

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“…As observed in previous in vivo studies [13, 29, 30], the parasitemia dropped to almost undetectable levels about one week post infection (S4 Fig, day 6), a phenomenon associated with the acute host immune response aimed to control infection [31]. The survival of +Tet mice infected with Trx2 RNAi parasites was significantly extended when compared to the animals where Trx2 expression was not silenced (Fig 2D; p = 0.044).…”

Section: Resultssupporting

confidence: 78%

An essential thioredoxin-type protein of Trypanosoma brucei acts as redox-regulated mitochondrial chaperone

et al. 2019

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Most known thioredoxin-type proteins (Trx) participate in redox pathways, using two highly conserved cysteine residues to catalyze thiol-disulfide exchange reactions. Here we demonstrate that the so far unexplored Trx2 from African trypanosomes (Trypanosoma brucei) lacks protein disulfide reductase activity but functions as an effective temperature-activated and redox-regulated chaperone. Immunofluorescence microscopy and fractionated cell lysis revealed that Trx2 is located in the mitochondrion of the parasite. RNA-interference and gene knock-out approaches showed that depletion of Trx2 impairs growth of both mammalian bloodstream and insect stage procyclic parasites. Procyclic cells lacking Trx2 stop proliferation under standard culture conditions at 27°C and are unable to survive prolonged exposure to 37°C, indicating that Trx2 plays a vital role that becomes augmented under heat stress. Moreover, we found that Trx2 contributes to the in vivo infectivity of T. brucei. Remarkably, a Trx2 version, in which all five cysteines were replaced by serine residues, complements for the wildtype protein in conditional knock-out cells and confers parasite infectivity in the mouse model. Characterization of the recombinant protein revealed that Trx2 can coordinate an iron sulfur cluster and is highly sensitive towards spontaneous oxidation. Moreover, we discovered that both wildtype and mutant Trx2 protect other proteins against thermal aggregation and preserve their ability to refold upon return to non-stress conditions. Activation of the chaperone function of Trx2 appears to be triggered by temperature-mediated structural changes and inhibited by oxidative disulfide bond formation. Our studies indicate that Trx2 acts as a novel chaperone in the unique single mitochondrion of T. brucei and reveal a new perspective regarding the physiological function of thioredoxin-type proteins in trypanosomes.

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Section: Resultssupporting

confidence: 78%

An essential thioredoxin-type protein of Trypanosoma brucei acts as redox-regulated mitochondrial chaperone

et al. 2019

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“…Studies have reported that the selenocysteine pathway is not essential for parasite survival under nonstress conditions as knockout cells for O-phosphoseryl-tRNA(Sec) selenium transferase (SepSecS), SPS or PSTK do not show impaired growth or infectivity (Bonilla et al 2016). Aeby et al (2009b) showed that T. brucei is highly sensitive to auranofin, a complex that targets selenoproteins, but so are SepSecS knockout cells, indicating that the trypanocidal effect may not be related to selenoproteins.…”

Section: Discussionmentioning

confidence: 99%

Selenocysteine in Trypanosoma evansi: Identification of the Genes selb, selc, seld, pstk, seltryp and the Selenophosphate Synthetase Protein

et al. 2021

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Selenoproteins have been described in all three domains of life and their function has been mainly associated with oxidative stress defense. Canonical elements required for selenoprotein production have been identified in members of the kinetoplastid group supporting the existence of a complete selenocysteine synthesis pathway in these organisms. Currently, nothing is known regarding the selenocysteine pathway in Trypanosoma evansi. In this study, we identified the expression of the elements selB, selC, selD, PSTK and selTRYP at the mRNA level in T. evansi. All translated proteins (selD, PSTK, selTRYP and selB) have the domains predicted and higher identity with Trypanosoma brucei. gambiense. The selenophosphate synthetase protein was localized in the cytoplasm. Our results support the existence of an active selenocysteine pathway in T. evansi.

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“…brucei viability [ 11 ]. SEPSECS knockout experiments further established that there is no significant contribution of selenoproteins to redox homeostasis in trypanosomatids [ 11 , 13 , 27 , 28 ]. Indeed, we further show that Tb SELENOT knockdown does not significantly impact PCF and BSF T .…”

Section: Discussionmentioning

confidence: 99%

“…This result was extended with the observation that Tb SEPSECS is not essential for normal growth of the bloodstream form (BSF) T . brucei [ 27 ] and its survival in the mammalian host [ 28 ]. In addition, a Tb SEPSECS knockout cell line did not show any growth disruption upon hydrogen peroxide-induced oxidative stress in PCF [ 27 ].…”

Section: Introductionmentioning

confidence: 99%

Trypanosomatid selenophosphate synthetase structure, function and interaction with selenocysteine lyase

Silva

Faim

et al. 2020

PLoS Negl Trop Dis

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Eukaryotes from the Excavata superphylum have been used as models to study the evolution of cellular molecular processes. Strikingly, human parasites of the Trypanosomatidae family ( T . brucei , T . cruzi and L . major ) conserve the complex machinery responsible for selenocysteine biosynthesis and incorporation in selenoproteins (SELENOK/SelK, SELENOT/SelT and SELENOTryp/SelTryp), although these proteins do not seem to be essential for parasite viability under laboratory controlled conditions. Selenophosphate synthetase (SEPHS/SPS) plays an indispensable role in selenium metabolism, being responsible for catalyzing the formation of selenophosphate, the biological selenium donor for selenocysteine synthesis. We solved the crystal structure of the L . major selenophosphate synthetase and confirmed that its dimeric organization is functionally important throughout the domains of life. We also demonstrated its interaction with selenocysteine lyase (SCLY) and showed that it is not present in other stable assemblies involved in the selenocysteine pathway, namely the phosphoseryl-tRNA Sec kinase (PSTK)-Sec-tRNA Sec synthase (SEPSECS) complex and the tRNA Sec -specific elongation factor (eEFSec) complex. Endoplasmic reticulum stress with dithiothreitol (DTT) or tunicamycin upon selenophosphate synthetase ablation in procyclic T . brucei cells led to a growth defect. On the other hand, only DTT presented a negative effect in bloodstream T . brucei expressing selenophosphate synthetase-RNAi. Furthermore, selenoprotein T (SELENOT) was dispensable for both forms of the parasite. Together, our data suggest a role for the T . brucei selenophosphate synthetase in the regulation of the parasite’s ER stress response.

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Selenoproteins of African trypanosomes are dispensable for parasite survival in a mammalian host

Cited by 15 publications

References 43 publications

An essential thioredoxin-type protein of Trypanosoma brucei acts as redox-regulated mitochondrial chaperone

An essential thioredoxin-type protein of Trypanosoma brucei acts as redox-regulated mitochondrial chaperone

Selenocysteine in Trypanosoma evansi: Identification of the Genes selb, selc, seld, pstk, seltryp and the Selenophosphate Synthetase Protein

Trypanosomatid selenophosphate synthetase structure, function and interaction with selenocysteine lyase

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