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Biological Chemistry

Editor-in-Chief: Brüne, Bernhard

Editorial Board Member: Buchner, Johannes / Ludwig, Stephan / Sies, Helmut / Turk, Boris / Wittinghofer, Alfred

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Cloning, functional analysis, and mitochondrial localization of Trypanosoma brucei monothiol glutaredoxin-1

Michael Filser1 / Marcelo A. Comini2 / Maria M. Molina-Navarro3 / Natalie Dirdjaja4 / Enrique Herrero5 / R. Luise Krauth-Siegel6

1Biochemie-Zentrum der Universität Heidelberg, Im Neuenheimer Feld 504, D-69120 Heidelberg, Germany

2Biochemie-Zentrum der Universität Heidelberg, Im Neuenheimer Feld 504, D-69120 Heidelberg, Germany

3Departament de Ciències Mèdiques Bàsiques, IRBLLEIDA, Universitat de Lleida, Monserrat Roig 2, E-25008 Lleida, Spain

4Biochemie-Zentrum der Universität Heidelberg, Im Neuenheimer Feld 504, D-69120 Heidelberg, Germany

5Departament de Ciències Mèdiques Bàsiques, IRBLLEIDA, Universitat de Lleida, Monserrat Roig 2, E-25008 Lleida, Spain

6Biochemie-Zentrum der Universität Heidelberg, Im Neuenheimer Feld 504, D-69120 Heidelberg, Germany

Corresponding author

Citation Information: Biological Chemistry. Volume 389, Issue 1, Pages 21–32, ISSN (Online) 14374315, ISSN (Print) 14316730, DOI: 10.1515/BC.2007.147, December 2007

Publication History:
Received:
2007-06-18
Accepted:
2007-07-22
Published Online:
2007-12-20

Abstract

African trypanosomes encode three monothiol glutaredoxins (1-C-Grx1 to 3). 1-C-Grx1 has a putative CAYS active site and Cys181 as single additional cysteine. The recombinant protein forms non-covalent homodimers. As observed for other monothiol glutaredoxins, Trypanosoma brucei 1-C-Grx1 was not active in the glutaredoxin assay with hydroxyethyl disulfide and glutathione nor catalyzed the reduction of insulin disulfide. In addition, it lacked peroxidase activity and did not catalyze protein (de)glutathionylation. Upon oxidation, 1-C-Grx1 forms an intramolecular disulfide bridge and, to a minor degree, covalent dimers. Both disulfide forms are reduced by the parasite trypanothione/tryparedoxin system. 1-C-Grx1 shows mitochondrial localization. The total cellular concentration is at least 5 μm. Thus, 1-C-Grx1 is an abundant protein especially in the rudimentary organelle of the mammalian form of the parasite. Expression of 1-C-Grx1 in Grx5-deficient yeast cells with its authentic presequence targeted the protein to the mitochondria and partially restored the growth phenotype and aconitase activity of the mutant, and conferred resistance against hydroperoxides and diamide. The parasite Grx2 and 3 failed to substitute for Grx5. This is surprising because even bacterial and plant 1-Cys-glutaredoxins efficiently revert the defects, and may be due to the lack of two basic residues conserved in all but the trypanosomatid proteins.

Keywords: monothiol glutaredoxin; thiol metabolism; Trypanosoma; trypanothione; tryparedoxin; yeast

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