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Title: The Enzymatic and Structural Basis for Inhibition of Echinococcus granulosus Thioredoxin Glutathione Reductase by Gold(I)

Abstract

Aims: New drugs are needed to treat flatworm infections that cause severe human diseases such as schistosomiasis. The unique flatworm enzyme thioredoxin glutathione reductase (TGR), structurally different from the human enzyme, is a key drug target. Structural studies of the flatworm Echinococcus granulosus TGR, free and complexed with AuI-MPO, a novel gold inhibitor, together with inhibition assays were performed. Results: AuI-MPO is a potent TGR inhibitor that achieves 75% inhibition at a 1:1 TGR:Au ratio and efficiently kills E. granulosus in vitro. The structures revealed salient insights: (i) unique monomer–monomer interactions, (ii) distinct binding sites for thioredoxin and the glutaredoxin (Grx) domain, (iii) a single glutathione disulfide reduction site in the Grx domain, (iv) rotation of the Grx domain toward the Sec-containing redox active site, and (v) a single gold atom bound to Cys519 and Cys573 in the AuI-TGR complex. Structural modeling suggests that these residues are involved in the stabilization of the Sec-containing C-terminus. Consistently, Cys→Ser mutations in these residues decreased TGR activities. Mass spectroscopy confirmed these cysteines are the primary binding site. Innovation: The identification of a primary site for gold binding and the structural model provide a basis for gold compound optimization through scaffold adjustments. Conclusions: Themore » structural study revealed that TGR functions are achieved not only through a mobile Sec-containing redox center but also by rotation of the Grx domain and distinct binding sites for Grx domain and thioredoxin. The conserved Cys519 and Cys573 residues targeted by gold assist catalysis through stabilization of the Sec-containing redox center. Antioxid. Redox Signal. 27, 1491–1504.« less

Authors:
 [1];  [2];  [3];  [4];  [3];  [3];  [5];  [5];  [6];  [7];  [6];  [3]
  1. Worm Biology Lab, Institut Pasteur de Montevideo, Montevideo, Uruguay.; Cátedra de Inmunología, Facultad de Química, Instituto de Higiene, Universidad de la República, Montevideo, Uruguay.
  2. Department of Biomedical Research, National Jewish Health, Denver, Colorado.; Department of Immunology and Microbiology, University of Colorado Denver, School of Medicine, Aurora, Colorado.; School of Science, Beijing Forestry University, Beijing, China.
  3. Department of Biomedical Research, National Jewish Health, Denver, Colorado.; Department of Immunology and Microbiology, University of Colorado Denver, School of Medicine, Aurora, Colorado.
  4. Cátedra de Inmunología, Facultad de Química, Instituto de Higiene, Universidad de la República, Montevideo, Uruguay.; Redox Biology of Trypanosomes, Institut Pasteur de Montevideo, Uruguay.
  5. Laboratório de Genômica Estrutural e Funcional, Centro de Biotecnologia, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brazil.
  6. Cátedra de Química Inorgánica, Facultad de Química, Universidad de la República, Montevideo, Uruguay.
  7. Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts.
Publication Date:
Research Org.:
Argonne National Lab. (ANL), Argonne, IL (United States). Advanced Photon Source (APS)
Sponsoring Org.:
USDOE Office of Science (SC)
OSTI Identifier:
1418056
Resource Type:
Journal Article
Resource Relation:
Journal Name: Antioxidants and Redox Signaling; Journal Volume: 27; Journal Issue: 18
Country of Publication:
United States
Language:
ENGLISH
Subject:
59 BASIC BIOLOGICAL SCIENCES

Citation Formats

Salinas, Gustavo, Gao, Wei, Wang, Yang, Bonilla, Mariana, Yu, Long, Novikov, Andrey, Virginio, Veridiana G., Ferreira, Henrique B., Vieites, Marisol, Gladyshev, Vadim N., Gambino, Dinorah, and Dai, Shaodong. The Enzymatic and Structural Basis for Inhibition of Echinococcus granulosus Thioredoxin Glutathione Reductase by Gold(I). United States: N. p., 2017. Web. doi:10.1089/ars.2016.6816.
Salinas, Gustavo, Gao, Wei, Wang, Yang, Bonilla, Mariana, Yu, Long, Novikov, Andrey, Virginio, Veridiana G., Ferreira, Henrique B., Vieites, Marisol, Gladyshev, Vadim N., Gambino, Dinorah, & Dai, Shaodong. The Enzymatic and Structural Basis for Inhibition of Echinococcus granulosus Thioredoxin Glutathione Reductase by Gold(I). United States. doi:10.1089/ars.2016.6816.
Salinas, Gustavo, Gao, Wei, Wang, Yang, Bonilla, Mariana, Yu, Long, Novikov, Andrey, Virginio, Veridiana G., Ferreira, Henrique B., Vieites, Marisol, Gladyshev, Vadim N., Gambino, Dinorah, and Dai, Shaodong. Wed . "The Enzymatic and Structural Basis for Inhibition of Echinococcus granulosus Thioredoxin Glutathione Reductase by Gold(I)". United States. doi:10.1089/ars.2016.6816.
@article{osti_1418056,
title = {The Enzymatic and Structural Basis for Inhibition of Echinococcus granulosus Thioredoxin Glutathione Reductase by Gold(I)},
author = {Salinas, Gustavo and Gao, Wei and Wang, Yang and Bonilla, Mariana and Yu, Long and Novikov, Andrey and Virginio, Veridiana G. and Ferreira, Henrique B. and Vieites, Marisol and Gladyshev, Vadim N. and Gambino, Dinorah and Dai, Shaodong},
abstractNote = {Aims: New drugs are needed to treat flatworm infections that cause severe human diseases such as schistosomiasis. The unique flatworm enzyme thioredoxin glutathione reductase (TGR), structurally different from the human enzyme, is a key drug target. Structural studies of the flatworm Echinococcus granulosus TGR, free and complexed with AuI-MPO, a novel gold inhibitor, together with inhibition assays were performed. Results: AuI-MPO is a potent TGR inhibitor that achieves 75% inhibition at a 1:1 TGR:Au ratio and efficiently kills E. granulosus in vitro. The structures revealed salient insights: (i) unique monomer–monomer interactions, (ii) distinct binding sites for thioredoxin and the glutaredoxin (Grx) domain, (iii) a single glutathione disulfide reduction site in the Grx domain, (iv) rotation of the Grx domain toward the Sec-containing redox active site, and (v) a single gold atom bound to Cys519 and Cys573 in the AuI-TGR complex. Structural modeling suggests that these residues are involved in the stabilization of the Sec-containing C-terminus. Consistently, Cys→Ser mutations in these residues decreased TGR activities. Mass spectroscopy confirmed these cysteines are the primary binding site. Innovation: The identification of a primary site for gold binding and the structural model provide a basis for gold compound optimization through scaffold adjustments. Conclusions: The structural study revealed that TGR functions are achieved not only through a mobile Sec-containing redox center but also by rotation of the Grx domain and distinct binding sites for Grx domain and thioredoxin. The conserved Cys519 and Cys573 residues targeted by gold assist catalysis through stabilization of the Sec-containing redox center. Antioxid. Redox Signal. 27, 1491–1504.},
doi = {10.1089/ars.2016.6816},
journal = {Antioxidants and Redox Signaling},
number = 18,
volume = 27,
place = {United States},
year = {Wed Dec 20 00:00:00 EST 2017},
month = {Wed Dec 20 00:00:00 EST 2017}
}