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Selenoprotein: Potential Player in Redox Regulation in Chlamydomonas reinhardtii. Antioxidants (Basel) 2022; 11:antiox11081630. [PMID: 36009349 PMCID: PMC9404770 DOI: 10.3390/antiox11081630] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2022] [Revised: 08/16/2022] [Accepted: 08/18/2022] [Indexed: 11/22/2022] Open
Abstract
Selenium (Se) is an essential micro-element for many organisms, including Chlamydomonas reinhardtii, and is required in trace amounts. It is obtained from the 21st amino acid selenocysteine (Sec, U), genetically encoded by the UGA codon. Proteins containing Sec are known as selenoproteins. In eukaryotes, selenoproteins are present in animals and algae, whereas fungi and higher plants lack them. The human genome contains 25 selenoproteins, most of which are involved in antioxidant defense activity, redox regulation, and redox signaling. In algae, 42 selenoprotein families were identified using various bioinformatics approaches, out of which C. reinhardtii is known to have 10 selenoprotein genes. However, the role of selenoproteins in Chlamydomonas is yet to be reported. Chlamydomonas selenoproteins contain conserved domains such as CVNVGC and GCUG, in the case of thioredoxin reductase, and CXXU in other selenoproteins. Interestingly, Sec amino acid residue is present in a catalytically active domain in Chlamydomonas selenoproteins, similar to human selenoproteins. Based on catalytical active sites and conserved domains present in Chlamydomonas selenoproteins, we suggest that Chlamydomonas selenoproteins could have a role in redox regulation and defense by acting as antioxidants in various physiological conditions.
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Lu J, Wei N, Cao J, Zhou Y, Gong H, Zhang H, Zhou J. Evaluation of enzymatic activity of Babesia microti thioredoxin reductase (Bmi TrxR)-mutants and screening of its potential inhibitors. Ticks Tick Borne Dis 2020; 12:101623. [PMID: 33418338 DOI: 10.1016/j.ttbdis.2020.101623] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2020] [Revised: 12/07/2020] [Accepted: 12/08/2020] [Indexed: 01/25/2023]
Abstract
Babesia microti is a zoonotic pathogen that mainly parasitizes mammalian erythrocytes. Oxidative stress can induce gene mutation, protein denaturation and lipid peroxidation, such as reactive oxygen species (ROS) induced by hypoxic environment and the host immune system. An antioxidase, B. microti thioredoxin reductase (Bmi TrxR), has been identified in B. microti. We used a combination of homology modeling and domain prediction to explore the functional sites of Bmi TrxR and found that TrxR has three domains. Constructed a mutant pool which His-tag were at the N-terminus (TrxR-Nhis, C105-Nhis, C110-Nhis, C105110-Nhis, C547-Nhis, C552-Nhis, C547552-Nhis) and the His tag were at the N- and C-terminus (TrxR-NChis, C547-NChis, C552-NChis, C547552-NChis). The proteins were expressed as His-tagged fusion proteins in Escherichia coli. The His-tag of TrxR C-terminus were affected the reaction with Trx. The inhibitory efficiency of DNCB was decreased for mutant C547, compared with recombinant TrxR, indicating that the action site of DNCB might be cysteine at position 547. These results indicate that the N-terminal active site of Bmi TrxR plays an important role in accepting electrons and promotes electron transfer. The C-terminus His tag of Bmi TrxR affected the electron transfer and the reducing activity of Bmi TrxR. Reduce reactive oxygen produced in oxidative stress was reduced by Bmi TrxR, which is beneficial to Babesia survival. Therefore, reduction site of TrxR may become a potential target for Babesia microti treatment.
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Affiliation(s)
- Jinmiao Lu
- Key Laboratory of Animal Parasitology of Ministry of Agriculture, Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Shanghai 200241, China
| | - Nana Wei
- Key Laboratory of Animal Parasitology of Ministry of Agriculture, Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Shanghai 200241, China
| | - Jie Cao
- Key Laboratory of Animal Parasitology of Ministry of Agriculture, Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Shanghai 200241, China
| | - Yongzhi Zhou
- Key Laboratory of Animal Parasitology of Ministry of Agriculture, Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Shanghai 200241, China
| | - Haiyan Gong
- Key Laboratory of Animal Parasitology of Ministry of Agriculture, Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Shanghai 200241, China
| | - Houshuang Zhang
- Key Laboratory of Animal Parasitology of Ministry of Agriculture, Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Shanghai 200241, China.
| | - Jinlin Zhou
- Key Laboratory of Animal Parasitology of Ministry of Agriculture, Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Shanghai 200241, China.
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Abstract
Protein semisynthesis-defined herein as the assembly of a protein from a combination of synthetic and recombinant fragments-is a burgeoning field of chemical biology that has impacted many areas in the life sciences. In this review, we provide a comprehensive survey of this area. We begin by discussing the various chemical and enzymatic methods now available for the manufacture of custom proteins containing noncoded elements. This section begins with a discussion of methods that are more chemical in origin and ends with those that employ biocatalysts. We also illustrate the commonalities that exist between these seemingly disparate methods and show how this is allowing for the development of integrated chemoenzymatic methods. This methodology discussion provides the technical foundation for the second part of the review where we cover the great many biological problems that have now been addressed using these tools. Finally, we end the piece with a short discussion on the frontiers of the field and the opportunities available for the future.
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Affiliation(s)
| | - Tom W. Muir
- Department of Chemistry, Princeton University, Frick Laboratory, Princeton, New Jersey 08544, United States
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Tuladhar A, Hondal RJ, Colon R, Hernandez EL, Rein KS. Effectors of thioredoxin reductase: Brevetoxins and manumycin-A. Comp Biochem Physiol C Toxicol Pharmacol 2019; 217:76-86. [PMID: 30476593 PMCID: PMC7485175 DOI: 10.1016/j.cbpc.2018.11.015] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/20/2018] [Accepted: 11/21/2018] [Indexed: 02/03/2023]
Abstract
The activities of two effectors, brevetoxin (PbTx) and manumycin-A (Man-A), of thioredoxin reductase (TrxR) have been evaluated against a series of fourteen TrxR orthologs originating from mammals, insects and protists and several mutants. Man-A, a molecule with numerous electrophilic sites, forms a covalent adduct with most selenocystine (Sec)-containing TrxR enzymes. The evidence also demonstrates that Man-A can form covalent adducts with some non-Sec-containing enzymes. The activities of TrxR enzymes towards various substrates are moderated by Man-A either positively or negatively depending on the enzyme. In general, the reduction of substrates by Sec-containing TrxR is inhibited and NADPH oxidase activity is activated. For non-Sec-containing TrxR the effect of Man-A on the reduction of substrates is variable, but NADPH oxidase activity can be activated even in the absence of covalent modification of TrxR. The effect of PbTx is less pronounced. A smaller subset of enzymes is affected by PbTx. With a single exception, the activities of most of this subset are activated. Although both PbTx variants can react with selenocysteine, a stable covalent adduct is not formed with any of the TrxR enzymes. The key findings from this work are (i) the identification of an alternate mechanism of toxicity for the algal toxin brevetoxin (ii) the demonstration that covalent modification of TrxR is not a prerequisite for the activation of NADPH oxidase activity of TrxR and (iii) the identification of an inhibitor which can discriminate between cytosolic and mitochondrial TrxR.
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Affiliation(s)
- Anupama Tuladhar
- Department of Chemistry and Biochemistry, Florida International University, 11200 SW 8th Street, Miami, FL 33199, United States
| | - Robert J Hondal
- Department of Biochemistry, 89 Beaumont Ave, Given Building Room 413B, Burlington, VT 05405, United States
| | - Ricardo Colon
- Department of Chemistry and Biochemistry, Florida International University, 11200 SW 8th Street, Miami, FL 33199, United States
| | - Elyssa L Hernandez
- Department of Chemistry and Biochemistry, Florida International University, 11200 SW 8th Street, Miami, FL 33199, United States
| | - Kathleen S Rein
- Department of Chemistry and Biochemistry, Florida International University, 11200 SW 8th Street, Miami, FL 33199, United States.
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Barber DR, Hondal RJ. Gain of function conferred by selenocysteine: catalytic enhancement of one-electron transfer reactions by thioredoxin reductase. Protein Sci 2018; 28:79-89. [PMID: 30052295 DOI: 10.1002/pro.3480] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2018] [Revised: 07/03/2018] [Accepted: 07/05/2018] [Indexed: 11/07/2022]
Abstract
Selenocysteine (Sec) is the 21st amino acid in the genetic code and it is present in a small number of proteins where it replaces the much more commonly used amino acid cysteine (Cys). It is both more complicated and bioenergetically costly to insert Sec into a protein in comparison to Cys, and this cost is most likely compensated by a gain of function to the enzyme/protein in which it is incorporated. Here we investigate one such gain of function, the enhancement of one-electron transfer catalysis. We compared the ability of Sec-containing mouse mitochondrial thioredoxin reductase (mTrxR2) to catalyze the reduction of bovine cytochrome c, ascorbyl radical, and dehydroascorbate in comparison to Cys-containing thioredoxin reductases from D. melanogaster (DmTrxR) and P. falciparum (PfTrxR). The Sec-containing mTrxR2 was able to reduce all three substrates, while the Cys-containing enzymes had little or no activity. In addition, we constructed Cys➔Sec mutants of DmTrxR and PfTrxR and found that this substitution resulted in a gain of function, as these mutant enzymes were now able to catalyze the reduction of these substrates. We also found that in the case of PfTrxR, reduction of cytochrome c was enhanced five-fold in a truncated PfTrxR in which the C-terminal redox center was removed. This shows that some of the ability of thioredoxin reductase to reduce this substrate comes from the flavin coenzyme. We also discuss a possible mechanism by which Sec-containing thioredoxin reductase reduces dehydroascorbate to ascorbate by two sequential, one-electron reductions, in part catalyzed by Sec.
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Affiliation(s)
- Drew R Barber
- Department of Biochemistry, 89 Beaumont Ave, Given Building Room B413, Burlington, Vermont, 05405
| | - Robert J Hondal
- Department of Biochemistry, 89 Beaumont Ave, Given Building Room B413, Burlington, Vermont, 05405
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6
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O'Keefe JP, Dustin CM, Barber D, Snider GW, Hondal RJ. A "Seleno Effect" Differentiates the Roles of Redox Active Cysteine Residues in Plasmodium falciparum Thioredoxin Reductase. Biochemistry 2018; 57:1767-1778. [PMID: 29485860 DOI: 10.1021/acs.biochem.8b00004] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Here, we introduce the concept of the "seleno effect" in the study of oxidoreductases that catalyze thiol/disulfide exchange reactions. In these reactions, selenium can replace sulfur as a nucleophile, electrophile, or leaving group, and the resulting change in rate (the seleno effect) is defined as kS/ kSe. In solution, selenium accelerates the rate of thiol/disulfide exchange regardless of its chemical role (e.g., nucleophile or electrophile). Here we show that this is not the case for enzyme catalyzed reactions and that the magnitude of the seleno effect can differentiate the role of each sulfur atom of a disulfide bond between that of an electrophile or leaving group. We used selenium for sulfur substitution to study the thiol/disulfide exchange step that occurs between the N-terminal redox center and the C-terminal disulfide-containing β-hairpin motif of Plasmodium falciparum thioredoxin reductase (PfTrxR), which has the sequence Gly-Cys535-Gly-Gly-Gly-Lys-Cys540-Gly. We assayed a truncated PfTrxR enzyme missing this C-terminal tail for disulfide-reductase activity using synthetic peptide substrates in which either Cys535 or Cys540 was replaced with selenocysteine (Sec). The results show that substitution of Cys535 with Sec resulted in a nearly 9-fold decrease in the rate of reduction, while substitution of Cys540 resulted in a 1.5-fold increase in the rate of reduction. We also produced full-length, semisynthetic enzymes in which Sec replaced either of these two Cys residues and observed similar results using E. coli thioredoxin as the substrate. In this assay, the observed seleno effect ( kS/ kSe) for the C535U mutant was 7.4, and that for the C540U mutant was 0.2.
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Affiliation(s)
- John P O'Keefe
- Department of Biochemistry , University of Vermont , 89 Beaumont Ave, Given Building Room B413 , Burlington , Vermont 05405 , United States
| | - Christopher M Dustin
- Department of Biochemistry , University of Vermont , 89 Beaumont Ave, Given Building Room B413 , Burlington , Vermont 05405 , United States
| | - Drew Barber
- Department of Biochemistry , University of Vermont , 89 Beaumont Ave, Given Building Room B413 , Burlington , Vermont 05405 , United States
| | - Gregg W Snider
- Department of Biochemistry , University of Vermont , 89 Beaumont Ave, Given Building Room B413 , Burlington , Vermont 05405 , United States
| | - Robert J Hondal
- Department of Biochemistry , University of Vermont , 89 Beaumont Ave, Given Building Room B413 , Burlington , Vermont 05405 , United States
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Chen W, Tuladhar A, Rolle S, Lai Y, Rodriguez Del Rey F, Zavala CE, Liu Y, Rein KS. Brevetoxin-2, is a unique inhibitor of the C-terminal redox center of mammalian thioredoxin reductase-1. Toxicol Appl Pharmacol 2017; 329:58-66. [PMID: 28551108 DOI: 10.1016/j.taap.2017.05.027] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2017] [Revised: 05/15/2017] [Accepted: 05/22/2017] [Indexed: 11/15/2022]
Abstract
Karenia brevis, the Florida red tide dinoflagellate produces a suite of neurotoxins known as the brevetoxins. The most abundant of the brevetoxins PbTx-2, was found to inhibit the thioredoxin-thioredoxin reductase system, whereas the PbTx-3 has no effect on this system. On the other hand, PbTx-2 activates the reduction of small disulfides such as 5,5'-dithio-bis-(2-nitrobenzoic acid) by thioredoxin reductase. PbTx-2 has an α, β-unsaturated aldehyde moiety which functions as an efficient electrophile and selenocysteine conjugates are readily formed. PbTx-2 blocks the inhibition of TrxR by the inhibitor curcumin, whereas curcumin blocks PbTx-2 activation of TrxR. It is proposed that the mechanism of inhibition of thioredoxin reduction is via the formation of a Michael adduct between selenocysteine and the α, β-unsaturated aldehyde moiety of PbTx-2. PbTx-2 had no effect on the rates of reactions catalyzed by related enzymes such as glutathione reductase, glutathione peroxidase or glutaredoxin.
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Affiliation(s)
- Wei Chen
- Department of Chemistry and Biochemistry, Florida International University, 11200 SW 8th Street, Miami, FL 33199, United States
| | - Anupama Tuladhar
- Department of Chemistry and Biochemistry, Florida International University, 11200 SW 8th Street, Miami, FL 33199, United States
| | - Shantelle Rolle
- Department of Chemistry and Biochemistry, Florida International University, 11200 SW 8th Street, Miami, FL 33199, United States
| | - Yanhao Lai
- Department of Chemistry and Biochemistry, Florida International University, 11200 SW 8th Street, Miami, FL 33199, United States
| | - Freddy Rodriguez Del Rey
- Department of Chemistry and Biochemistry, Florida International University, 11200 SW 8th Street, Miami, FL 33199, United States
| | - Cristian E Zavala
- Department of Chemistry and Biochemistry, Florida International University, 11200 SW 8th Street, Miami, FL 33199, United States
| | - Yuan Liu
- Department of Chemistry and Biochemistry, Florida International University, 11200 SW 8th Street, Miami, FL 33199, United States; Biomolecular Sciences Institute, School of Integrated Sciences and Humanity, Florida International University, 11200 SW 8th Street, Miami, FL 33199, United States
| | - Kathleen S Rein
- Department of Chemistry and Biochemistry, Florida International University, 11200 SW 8th Street, Miami, FL 33199, United States.
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8
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The Architecture of Thiol Antioxidant Systems among Invertebrate Parasites. Molecules 2017; 22:molecules22020259. [PMID: 28208651 PMCID: PMC6155587 DOI: 10.3390/molecules22020259] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2016] [Accepted: 02/03/2017] [Indexed: 01/14/2023] Open
Abstract
The use of oxygen as the final electron acceptor in aerobic organisms results in an improvement in the energy metabolism. However, as a byproduct of the aerobic metabolism, reactive oxygen species are produced, leaving to the potential risk of an oxidative stress. To contend with such harmful compounds, living organisms have evolved antioxidant strategies. In this sense, the thiol-dependent antioxidant defense systems play a central role. In all cases, cysteine constitutes the major building block on which such systems are constructed, being present in redox substrates such as glutathione, thioredoxin, and trypanothione, as well as at the catalytic site of a variety of reductases and peroxidases. In some cases, the related selenocysteine was incorporated at selected proteins. In invertebrate parasites, antioxidant systems have evolved in a diversity of both substrates and enzymes, representing a potential area in the design of anti-parasite strategies. The present review focus on the organization of the thiol-based antioxidant systems in invertebrate parasites. Differences between these taxa and its final mammal host is stressed. An understanding of the antioxidant defense mechanisms in this kind of parasites, as well as their interactions with the specific host is crucial in the design of drugs targeting these organisms.
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Identification of a thioredoxin reductase from Babesia microti during mammalian infection. Parasitol Res 2016; 115:3219-27. [PMID: 27164832 DOI: 10.1007/s00436-016-5084-4] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2016] [Accepted: 04/20/2016] [Indexed: 10/21/2022]
Abstract
Babesia microti is the primary causative agent of human babesiosis worldwide and associated with increased human health risks and the safety of blood supply. The parasite replicates in the host's red blood cells, thus, in order to counteract the oxidative stress and toxic effects, parasites employ a thioredoxin (Trx) system to maintain a redox balance. Since thioredoxin reductase (TrxR) plays a critical role in the system, in this study, we report the cloning, expression, and functional characterization of a novel TrxR from B. microti (BmiTrxR). The complete gene BmiTrxR was obtained by amplifying the 5' and 3' regions of messenger RNA (mRNA) by RACE. The full-length complementary DNA (cDNA) of BmiTrxR was 1766 bp and contained an intact open reading frame with 1662 bp that encoded a polypeptide with 553 amino acids. Molecular weight of the predicted protein was 58.4 kDa with an isoelectric point of 6.95, similar to high molecular weight TrxR. The recombinant protein of BmiTrxR was expressed in a His-fused soluble form in Escherichia coli. The native protein BmiTrxR was identified with the mouse anti-BmiTrxR polyclonal serum by western blotting and IFAT. Moreover, the enzyme showed a disulfide reductase activity using DTNB as substrate and catalyzed the NADPH-dependent reduction of Trx. Auranofin, a known inhibitor of TrxR, completely abrogated the activity of the recombinant enzyme in vitro. These results not only contribute to the understanding of redox pathway in this parasite but also suggest that BmiTrxR could be a potential target for the development of novel strategies to control B. microti thus reducing the incidence of babesiosis.
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Xu J, Cheng Q, Arnér ESJ. Details in the catalytic mechanism of mammalian thioredoxin reductase 1 revealed using point mutations and juglone-coupled enzyme activities. Free Radic Biol Med 2016; 94:110-20. [PMID: 26898501 DOI: 10.1016/j.freeradbiomed.2016.02.013] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/22/2015] [Revised: 02/08/2016] [Accepted: 02/15/2016] [Indexed: 01/04/2023]
Abstract
The mammalian selenoprotein thioredoxin reductase 1 (TrxR1) is a key enzyme in redox regulation, antioxidant defense, and cellular growth. TrxR1 can catalyze efficient reduction of juglone (5-hydroxy-1,4-naphthoquinone; walnut toxin) in a reaction which, in contrast to reduction of most other substrates of TrxR1, is not dependent upon an intact selenocysteine (Sec, U) residue of the enzyme. Using a number of TrxR1 mutant variants, we here found that a sole Cys residue at the C-terminal tail of TrxR1 is required for high-efficiency juglone-coupled NADPH oxidase activity of Sec-deficient enzyme, occurring with mixed one- and two-electron reactions producing superoxide. The activity also utilizes the FAD and the N-terminal redox active disulfide/dithiol motif of TrxR1. If a sole Cys residue at the C-terminal tail of TrxR1, in the absence of Sec, was moved further towards the C-terminal end of the protein compared to its natural position at residue 497, juglone reduction was, surprisingly, further increased. Ala substitutions of Trp407, Asn418 and Asn419 in a previously described "guiding bar", thought to mediate interactions of the C-terminal tail of TrxR1 with the FAD/dithiol site at the N-terminal domain of the other subunit in the dimeric enzyme, lowered turnover with juglone about 4.5-fold. Four residues of Sec-deficient TrxR1 were found to be easily arylated by juglone, including the Cys residue at position 497. Based upon our observations we suggest a model for involvement of the juglone-arylated C-terminal motif of TrxR1 to explain its high activity with juglone. This study thus provides novel insights into the catalytic mechanisms of TrxR1. One-electron juglone reduction by TrxR1 producing superoxide should furthermore contribute to the well-known prooxidant cytotoxicity of juglone.
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Affiliation(s)
- Jianqiang Xu
- School of Life Science and Medicine, Dalian University of Technology, Panjin 124221, China; Division of Biochemistry, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, SE-17177 Stockholm, Sweden
| | - Qing Cheng
- Division of Biochemistry, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, SE-17177 Stockholm, Sweden
| | - Elias S J Arnér
- Division of Biochemistry, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, SE-17177 Stockholm, Sweden.
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Tamaki S, Maruta T, Sawa Y, Shigeoka S, Ishikawa T. Biochemical and physiological analyses of NADPH-dependent thioredoxin reductase isozymes in Euglena gracilis. PLANT SCIENCE : AN INTERNATIONAL JOURNAL OF EXPERIMENTAL PLANT BIOLOGY 2015; 236:29-36. [PMID: 26025518 DOI: 10.1016/j.plantsci.2015.03.016] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/02/2015] [Revised: 03/14/2015] [Accepted: 03/23/2015] [Indexed: 06/04/2023]
Abstract
At least four peroxiredoxins that are coupled with the thioredoxin (Trx) system have been shown to play a key role in redox metabolism in the unicellular phytoflagellate Euglena gracilis. In order to clarify Trx-mediated redox regulation in this alga, we herein identified three NADPH-dependent thioredoxin reductases (NTRs) using a homologous search and characterized their enzymatic properties and physiological roles. Each Euglena NTR protein belonged to the small, large, and NTRC types, and were named EgNTR1, EgNTR2, and EgNTRC, respectively. EgNTR2 was phylogenetically different from the known NTRs in eukaryotic algae. EgNTR1 was predicted to be localized in mitochondria, EgNTR2 in the cytosol, and EgNTRC in plastids. The catalytic efficiency of EgNTR2 for NADPH was 30-46-fold higher than those of EgNTR1 and truncated form of EgNTRC, suggested that large type EgNTR2 reduced Trx more efficiently. The silencing of EgNTR2 gene expression resulted in significant growth inhibition and cell hypertrophy in Euglena cells. These results suggest that EgNTRs function in each cellular compartment and are physiologically important, particularly in the cytosol.
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Affiliation(s)
- Shun Tamaki
- Department of Life Science and Biotechnology, Faculty of Life and Environmental Science, Shimane University, 1060 Nishikawatsu, Matsue, Shimane 690-8504, Japan
| | - Takanori Maruta
- Department of Life Science and Biotechnology, Faculty of Life and Environmental Science, Shimane University, 1060 Nishikawatsu, Matsue, Shimane 690-8504, Japan; Core Research for Evolutional Science and Technology (CREST), Japan Science and Technology Agency (JST), Chiyoda-ku, Tokyo 102-0076, Japan
| | - Yoshihiro Sawa
- Department of Life Science and Biotechnology, Faculty of Life and Environmental Science, Shimane University, 1060 Nishikawatsu, Matsue, Shimane 690-8504, Japan
| | - Shigeru Shigeoka
- Department of Advanced Bioscience, Faculty of Agriculture, Kinki University, 3327-204 Nakamachi, Nara 631-8505, Japan; Core Research for Evolutional Science and Technology (CREST), Japan Science and Technology Agency (JST), Chiyoda-ku, Tokyo 102-0076, Japan
| | - Takahiro Ishikawa
- Department of Life Science and Biotechnology, Faculty of Life and Environmental Science, Shimane University, 1060 Nishikawatsu, Matsue, Shimane 690-8504, Japan; Core Research for Evolutional Science and Technology (CREST), Japan Science and Technology Agency (JST), Chiyoda-ku, Tokyo 102-0076, Japan.
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12
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McCarty SE, Schellenberger A, Goodwin DC, Fuanta NR, Tekwani BL, Calderón AI. Plasmodium falciparum Thioredoxin Reductase (PfTrxR) and Its Role as a Target for New Antimalarial Discovery. Molecules 2015; 20:11459-73. [PMID: 26111176 PMCID: PMC6272602 DOI: 10.3390/molecules200611459] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2015] [Revised: 06/12/2015] [Accepted: 06/17/2015] [Indexed: 11/17/2022] Open
Abstract
The growing resistance to current antimalarial drugs is a major concern for global public health. The pressing need for new antimalarials has led to an increase in research focused on the Plasmodium parasites that cause human malaria. Thioredoxin reductase (TrxR), an enzyme needed to maintain redox equilibrium in Plasmodium species, is a promising target for new antimalarials. This review paper provides an overview of the structure and function of TrxR, discusses similarities and differences between the thioredoxin reductases (TrxRs) of different Plasmodium species and the human forms of the enzyme, gives an overview of modeling Plasmodium infections in animals, and suggests the role of Trx functions in antimalarial drug resistance. TrxR of Plasmodium falciparum is a central focus of this paper since it is the only Plasmodium TrxR that has been crystallized and P. falciparum is the species that causes most malaria cases. It is anticipated that the information summarized here will give insight and stimulate new directions in which research might be most beneficial.
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Affiliation(s)
- Sara E McCarty
- College of Sciences and Mathematics, Auburn University, Auburn, AL 36849, USA.
- Department of Drug Discovery and Development, Harrison School of Pharmacy, Auburn University, Auburn, AL 36849, USA.
| | - Amanda Schellenberger
- Department of Drug Discovery and Development, Harrison School of Pharmacy, Auburn University, Auburn, AL 36849, USA.
- College of Agriculture, Auburn University, Auburn, AL 36849, USA.
| | - Douglas C Goodwin
- Department of Chemistry and Biochemistry, Auburn University, Auburn, AL 36849, USA.
| | - Ngolui Rene Fuanta
- Department of Chemistry and Biochemistry, Auburn University, Auburn, AL 36849, USA.
| | - Babu L Tekwani
- National Center for Natural Products Research and Department of BioMolecular Sciences, School of Pharmacy, University of Mississippi, Oxford, MS 38677, USA.
| | - Angela I Calderón
- Department of Drug Discovery and Development, Harrison School of Pharmacy, Auburn University, Auburn, AL 36849, USA.
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13
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Xu J, Eriksson SE, Cebula M, Sandalova T, Hedström E, Pader I, Cheng Q, Myers CR, Antholine WE, Nagy P, Hellman U, Selivanova G, Lindqvist Y, Arnér ESJ. The conserved Trp114 residue of thioredoxin reductase 1 has a redox sensor-like function triggering oligomerization and crosslinking upon oxidative stress related to cell death. Cell Death Dis 2015; 6:e1616. [PMID: 25611390 PMCID: PMC4669772 DOI: 10.1038/cddis.2014.574] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2014] [Revised: 11/19/2014] [Accepted: 12/03/2014] [Indexed: 12/19/2022]
Abstract
The selenoprotein thioredoxin reductase 1 (TrxR1) has several key roles in cellular redox systems and reductive pathways. Here we discovered that an evolutionarily conserved and surface-exposed tryptophan residue of the enzyme (Trp114) is excessively reactive to oxidation and exerts regulatory functions. The results indicate that it serves as an electron relay communicating with the FAD moiety of the enzyme, and, when oxidized, it facilitates oligomerization of TrxR1 into tetramers and higher multimers of dimers. A covalent link can also be formed between two oxidized Trp114 residues of two subunits from two separate TrxR1 dimers, as found both in cell extracts and in a crystal structure of tetrameric TrxR1. Formation of covalently linked TrxR1 subunits became exaggerated in cells on treatment with the pro-oxidant p53-reactivating anticancer compound RITA, in direct correlation with triggering of a cell death that could be prevented by antioxidant treatment. These results collectively suggest that Trp114 of TrxR1 serves a function reminiscent of an irreversible sensor for excessive oxidation, thereby presenting a previously unrecognized level of regulation of TrxR1 function in relation to cellular redox state and cell death induction.
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Affiliation(s)
- J Xu
- Division of Biochemistry, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, SE-17177 Stockholm, Sweden
| | - S E Eriksson
- Division of Biochemistry, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, SE-17177 Stockholm, Sweden
| | - M Cebula
- Division of Biochemistry, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, SE-17177 Stockholm, Sweden
| | - T Sandalova
- Division of Molecular Structural Biology, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, SE-17177 Stockholm, Sweden
| | - E Hedström
- Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, SE-17177 Stockholm, Sweden
| | - I Pader
- Division of Biochemistry, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, SE-17177 Stockholm, Sweden
| | - Q Cheng
- Division of Biochemistry, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, SE-17177 Stockholm, Sweden
| | - C R Myers
- Department of Pharmacology and Toxicology, Medical College of Wisconsin, 8701 Watertown Plank Road, Milwaukee, WI 53226, USA
| | - W E Antholine
- Department of Biophysics, Medical College of Wisconsin, 8701 Watertown Plank Road, Milwaukee, WI 53226, USA
| | - P Nagy
- Department of Molecular Immunology and Toxicology, National Institute of Oncology, Rath György ut 7-91, 1122, Budapest, Hungary
| | - U Hellman
- Ludwig Institutet for Cancer Research Ltd., Uppsala University BMC, SE-75 124 Uppsala, Sweden
| | - G Selivanova
- Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, SE-17177 Stockholm, Sweden
| | - Y Lindqvist
- Division of Molecular Structural Biology, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, SE-17177 Stockholm, Sweden
| | - E S J Arnér
- Division of Biochemistry, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, SE-17177 Stockholm, Sweden
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14
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Afanador GA, Matthews KA, Bartee D, Gisselberg JE, Walters MS, Freel Meyers CL, Prigge ST. Redox-dependent lipoylation of mitochondrial proteins in Plasmodium falciparum. Mol Microbiol 2014; 94:156-71. [PMID: 25116855 PMCID: PMC4177315 DOI: 10.1111/mmi.12753] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/08/2014] [Indexed: 11/26/2022]
Abstract
Lipoate scavenging from the human host is essential for malaria parasite survival. Scavenged lipoate is covalently attached to three parasite proteins: the H-protein and the E2 subunits of branched chain amino acid dehydrogenase (BCDH) and α-ketoglutarate dehydrogenase (KDH). We show mitochondrial localization for the E2 subunits of BCDH and KDH, similar to previously localized H-protein, demonstrating that all three lipoylated proteins reside in the parasite mitochondrion. The lipoate ligase 1, LipL1, has been shown to reside in the mitochondrion and it catalyses the lipoylation of the H-protein; however, we show that LipL1 alone cannot lipoylate BCDH or KDH. A second mitochondrial protein with homology to lipoate ligases, LipL2, does not show ligase activity and is not capable of lipoylating any of the mitochondrial substrates. Instead, BCDH and KDH are lipoylated through a novel mechanism requiring both LipL1 and LipL2. This mechanism is sensitive to redox conditions where BCDH and KDH are exclusively lipoylated under strong reducing conditions in contrast to the H-protein which is preferentially lipoylated under less reducing conditions. Thus, malaria parasites contain two different routes of mitochondrial lipoylation, an arrangement that has not been described for any other organism.
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Affiliation(s)
- Gustavo A Afanador
- Department of Molecular Microbiology and Immunology, Johns Hopkins School of Public Health, Baltimore, MD, USA
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