An unusual mode of iron–sulfur-cluster coordination in a teleost glutaredoxin

Bräutigam, Lars; Johansson, C.; Kubsch, Bastian; McDonough, Michael A.; Bill, Eckhard; Holmgren, Arne; Berndt, Carsten

doi:10.1016/j.bbrc.2013.05.132

Cited by 15 publications

(10 citation statements)

References 37 publications

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“…In its holo-form, namely with the FeS-cluster bound, almost all class II Grx were reported to dimerize using the active site cysteine from each monomer and two molecules of glutathione (GSH) as iron ligands. To our knowledge, the only Grx reported to bind the cluster as a monomer without employing GSH in the coordination is zebrafish Grx2 13 . In most organisms, the GSH/glutathione reductase (GR) pair act concertedly to maintain reduced redox-active Grx at the expenses of NADPH 11 .…”

Section: Introductionmentioning

confidence: 99%

The lineage-specific, intrinsically disordered N-terminal extension of monothiol glutaredoxin 1 from trypanosomes contains a regulatory region

Sturlese

Manta

Bertarello

et al. 2018

Sci Rep

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Glutaredoxins (Grx) are small proteins conserved throughout all the kingdoms of life that are engaged in a wide variety of biological processes and share a common thioredoxin-fold. Among them, class II Grx are redox-inactive proteins involved in iron-sulfur (FeS) metabolism. They contain a single thiol group in their active site and use low molecular mass thiols such as glutathione as ligand for binding FeS-clusters. In this study, we investigated molecular aspects of 1CGrx1 from the pathogenic parasite Trypanosoma brucei brucei, a mitochondrial class II Grx that fulfills an indispensable role in vivo. Mitochondrial 1CGrx1 from trypanosomes differs from orthologues in several features including the presence of a parasite-specific N-terminal extension (NTE) whose role has yet to be elucidated. Previously we have solved the structure of a truncated form of 1CGrx1 containing only the conserved glutaredoxin domain but lacking the NTE. Our aim here is to investigate the effect of the NTE on the conformation of the protein. We therefore solved the NMR structure of the full-length protein, which reveals subtle but significant differences with the structure of the NTE-less form. By means of different experimental approaches, the NTE proved to be intrinsically disordered and not involved in the non-redox dependent protein dimerization, as previously suggested. Interestingly, the portion comprising residues 65–76 of the NTE modulates the conformational dynamics of the glutathione-binding pocket, which may play a role in iron-sulfur cluster assembly and delivery. Furthermore, we disclosed that the class II-strictly conserved loop that precedes the active site is critical for stabilizing the protein structure. So far, this represents the first communication of a Grx containing an intrinsically disordered region that defines a new protein subgroup within class II Grx.

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Section: Introductionmentioning

confidence: 99%

The lineage-specific, intrinsically disordered N-terminal extension of monothiol glutaredoxin 1 from trypanosomes contains a regulatory region

Sturlese

Manta

Bertarello

et al. 2018

Sci Rep

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“…The absorption spectra of dimeric and oligomeric forms of recombinant Trx2 suggested that the protein can coordinate iron sulfur clusters. Only a small subset of Trx-fold proteins, most of them representing mono- or dithiol glutaredoxins [13, 26, 43, 56, 57], have been shown to bind iron sulfur clusters. The first natural Trx found to bind an iron sulfur cluster is IsTRP, a protein from the tapeworm Echinococcus granulosus [44].…”

Section: Discussionmentioning

confidence: 99%

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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“…Different types of Fe/S have been shown to be bound to Grxs (54). In addition to this canonical binding through GSH, an unusual mode of Fe/S coordination was reported in Grx2 from the teleost fish (8). The monomeric form of this protein can bind Fe/S using four Cys residues different from the CxxC active site.…”

Section: Bisiomentioning

confidence: 99%