The Dithiol Glutaredoxins of African Trypanosomes Have Distinct Roles and Are Closely Linked to the Unique Trypanothione Metabolism

Ceylan, Sevgi; Seidel, V; Ziebart, Nicole; Berndt, Carsten; Dirdjaja, Natalie; Krauth‐Siegel, R. Luise

doi:10.1074/jbc.m110.165860

Cited by 68 publications

(99 citation statements)

References 64 publications

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“…TDR1 is able to catalyze the deglutathionylation of both small molecule mixed-disulfides and glutathionylated bovine serum albumin as efficiently as LiGRX1 (Table 1, Table S2). When a glutathionylated peptide (peptide-SG) was used as a substrate, the k cat obtained with TDR1 was comparable to published values for different glutaredoxins (16) (Table S2). The K m for a peptide-S-SG was 40-fold higher for TDR1 than for LiGRX1, but the turnover of the glutathionylated peptide by TDR1 was also higher.…”

Section: Resultssupporting

confidence: 58%

“…A lysine is highly conserved in the active site of glutaredoxins (9), e.g., Lys34 in human glutaredoxin, and the side chain interacts directly with the C-terminal carboxylate of the GSH glycine moiety. This basic residue is not, however, conserved in trypanosomatid GRXs (16) nor in either TDR1 G-site where it is replaced by Glu40 or Gln267. This difference may represent an adaptation for binding TðSHÞ 2 that, because the GSH glycine is conjugated to spermidine, lacks a carboxylate group.…”

Section: Resultsmentioning

confidence: 99%

“…TDR1 can use TðSHÞ 2 as a substrate. The homolog of LiGRX1 in Trypanosoma brucei (TbGRX1) is reduced preferentially by TðSHÞ 2 with the rate constant k 2 several orders of magnitude higher than for reduction by GSH (16). A lysine is highly conserved in the active site of glutaredoxins (9), e.g., Lys34 in human glutaredoxin, and the side chain interacts directly with the C-terminal carboxylate of the GSH glycine moiety.…”

Section: Resultsmentioning

confidence: 99%

“…A series of enzyme assays, using published methods, were carried out to assess TDR1 for thioltransferase, disulfide reductase, peroxidase, and peptide deglutathionylation activities (15,16,19,20).…”

Section: Methodsmentioning

confidence: 99%

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LeishmaniaTDR1 structure, a unique trimeric glutathione transferase capable of deglutathionylation and antimonial prodrug activation

Fyfe

Westrop

Silva

et al. 2012

Proc. Natl. Acad. Sci. U.S.A.

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Thiol-dependent reductase I (TDR1), an enzyme found in parasitic Leishmania species and Trypanosoma cruzi, is implicated in deglutathionylation and activation of antimonial prodrugs used to treat leishmaniasis. The 2.3 Å resolution structure of TDR1 reveals a unique trimer of subunits each containing two glutathione-S-transferase (GST) domains. The similarities of individual domains and comparisons with GST classes suggest that TDR1 evolved by gene duplication, diversification, and gene fusion; a combination of events previously unknown in the GST protein superfamily and potentially explaining the distinctive enzyme properties of TDR1. The deglutathionylation activity of TDR1 implies that glutathione itself has regulatory intracellular roles in addition to being a precursor for trypanothione, the major low mass thiol present in trypanosomatids. We propose that activation of antiparasite Sb (V)-drugs is a legacy of the deglutathionylation activity of TDR1 and involves processing glutathione adducts with concomitant reduction of the metalloid to active Sb(III) species.thioltransferase | crystal structure | protozoan biology | redox metabolism T he kinetoplastid parasites Leishmania species and Trypanosoma cruzi infect humans, proliferate intracellularly, and cause the leishmaniases and Chagas disease, respectively. These parasites possess a thiol-dependent reductase known as thiol-dependent reductase I (TDR1) (1) or, specifically in T. cruzi, Tc52 (2). In Leishmania, TDR1 is implicated in redox regulation and in mediating susceptibility to the antimonial prodrugs Pentostam and Glucantime that represent frontline treatments (3). The therapeutic activity of these drugs follows reduction of the relatively inert pentavalent metalloid to more toxic trivalent species. This process occurs slowly in vitro in the presence of low molecular mass thiols such as glutathione (GSH) or the trypanosomatid-specific polyamine-GSH conjugate called trypanothione [TðSHÞ 2 ], especially at low pH as found in the parasitophorous vacuole in which Leishmania resides intracellularly in macrophages (4, 5). However, TDR1, in the presence of glutathione, catalyzes the reduction of Sb(V) in vitro and hence can mediate activation of the antimonial prodrugs (1). This finding correlates with the observation that in Leishmania major the enzyme is significantly more abundant in the form of the parasite (the amastigote) that infects the mammalian host than in the promastigote or insect form and that the amastigotes are strikingly more sensitive to Sb(V) than promastigotes (1, 6).TDR1 belongs to the glutathione-S-transferase (GST) superfamily (1), members of which contribute to varied, important biological events, including xenobiotic detoxification, stress response, and signaling processes. GSTs are classified into distinct subgroups on the basis of sequence, structure, immunological properties, and type of substrate (7-10). However, TDR1 has distinctive and unique properties (1). For example, the enzyme consists of fused GST-type domains for which t...

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Section: Resultssupporting

confidence: 58%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

See 2 more Smart Citations

LeishmaniaTDR1 structure, a unique trimeric glutathione transferase capable of deglutathionylation and antimonial prodrug activation

Fyfe

Westrop

Silva

et al. 2012

Proc. Natl. Acad. Sci. U.S.A.

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“…The dithiol T(SH) 2 constitutes the main low molecular mass thiol of trypanosomatids and acts as redox cofactor in a plethora of cellular functions (39,44,45). The transfer of reducing equivalents from T(SH) 2 to protein targets can be mediated by thioredoxin-(Trx), tryparedoxin-(TXN) and glutaredoxin-type oxidoreductases (12,20,63,77; Fig. 1B).…”

mentioning

confidence: 99%

Mono- and Dithiol Glutaredoxins in the Trypanothione-Based Redox Metabolism of Pathogenic Trypanosomes

Comini

Krauth‐Siegel²,

Bellanda³

2013

Antioxidants & Redox Signaling

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Significance: Glutaredoxins are ubiquitous small thiol proteins of the thioredoxin-fold superfamily. Two major groups are distinguished based on their active sites: the dithiol (2-C-Grxs) and the monothiol (1-C-Grxs) glutaredoxins with a CXXC and a CXXS active site motif, respectively. Glutaredoxins are involved in cellular redox and/or iron sulfur metabolism. Usually their functions are closely linked to the glutathione system. Trypanosomatids, the causative agents of several tropical diseases, rely on trypanothione as principal low molecular mass thiol, and their glutaredoxins readily react with the unique bis(glutathionyl) spermidine conjugate.

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Trypanothione‐Based Redox Metabolism of Trypanosomatids

Comini

Flohé

2013

Trypanosomatid Diseases

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The Dithiol Glutaredoxins of African Trypanosomes Have Distinct Roles and Are Closely Linked to the Unique Trypanothione Metabolism

Cited by 68 publications

References 64 publications

LeishmaniaTDR1 structure, a unique trimeric glutathione transferase capable of deglutathionylation and antimonial prodrug activation

LeishmaniaTDR1 structure, a unique trimeric glutathione transferase capable of deglutathionylation and antimonial prodrug activation

Mono- and Dithiol Glutaredoxins in the Trypanothione-Based Redox Metabolism of Pathogenic Trypanosomes

Trypanothione‐Based Redox Metabolism of Trypanosomatids

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