Versatility of Selenium Catalysis in PHGPx Unraveled by LC/ESI-MS/MS
-
P. Mauri
Abstract
Phospholipid hydroperoxide glutathione peroxidase (PHGPx; EC 1.11.1.12), a broad-spectrum thiol-dependent peroxidase, deserves renewed interest as a regulatory factor in various signaling cascades and as a structural protein in sperm cells. We present a first attempt to identify catalytic intermediates and derivatives of the selenoprotein by liquid chromatography coupled to electrospray tandem mass spectrometry (LC/ESI-MS/MS) and to explain observed specificities by molecular modeling. The ground state enzyme E proved to correspond to position 3-170 of the deduced porcine sequence with selenium being present as selenocysteine at position 46. The selenenic acid form, which is considered to be the first catalytic intermediate F formed by reaction with hydroperoxide, could not be identified. The second catalytic intermediate G was detected as Se-glutathionylated enzyme. This intermediate is generated in the reverse reaction where the active site selenol interacts with glutathione disulfide (GSSG). According to molecular models, specific binding of reduced glutathione (GSH) and of GSSG is inter alia facilitated by electrostatic attraction of Lys-48 and Lys-125. Polymerization of PHGPx is obtained under oxidizing conditions in the absence of low molecular weight thiols. Analysis of MS spectra revealed that the process is due to a selective reaction of Sec-46 with Cys-148' resulting in linear polymers representing deadend intermediates (G'). FT Docking of PHGPx molecules allowed reactions of Sec-46 with either Cys-66', Cys-107', Cys-168' or Cys-148', the latter option being most likely as judged by the number of proposed intermediates with reasonable hydrogen bonds, interaction energies and interface areas. We conclude that the same catalytic principles, depending on the conditions, can drive the diverse actions of PHGPx, i.e. hydroperoxide reduction, GSSG reduction, S-derivatization and self-incorporation into biological structures.
Copyright © 2003 by Walter de Gruyter GmbH & Co. KG
Articles in the same Issue
- Glutathione, Related Enzymology, and Leopold Flohé
- 'Lest I Forget Thee, Glutathione...'
- Glutathione Pathways in the Brain
- The Role of Glutathione Peroxidases in Trypanosomatids
- Cytoprotection against Oxidative Stress and the Regulation of Glutathione Synthesis
- The Parasite-Specific Trypanothione Metabolism of Trypanosoma and Leishmania
- Glutathione – Functions and Metabolism in the Malarial Parasite Plasmodium falciparum
- Oxidative Stress Caused by Inactivation of Glutathione Peroxidase and Adaptive Responses
- Versatility of Selenium Catalysis in PHGPx Unraveled by LC/ESI-MS/MS
- Modulation of the Chymotrypsin-Like Activity of the 20S Proteasome by Intracellular Redox Status: Effects of Glutathione Peroxidase-1 Overexpression and Antioxidant Drugs
- Microflora Trigger Colitis in Mice Deficient in Selenium-Dependent Glutathione Peroxidase and Induce Gpx2 Gene Expression
- Recruitment of the Interleukin-1 Receptor (IL-1RI)-Associated Kinase IRAK to the IL-1RI Is Redox Regulated
- Kinetics and Redox-Sensitive Oligomerisation Reveal Negative Subunit Cooperativity in Tryparedoxin Peroxidase of Trypanosoma brucei brucei
- Testis-Specific Expression of the Nuclear Form of Phospholipid Hydroperoxide Glutathione Peroxidase (PHGPx)
- Selective Recognition of Peptide Sequences by Glutathione Transferases: A Possible Mechanism for Modulation of Cellular Stress-Induced Signaling Pathways
- Biosynthesis of Trypanothione in Trypanosoma brucei brucei
- Transcriptional Regulation of Cytosol and Membrane Alanyl-Aminopeptidase in Human T Cell Subsets
- Regulation of Gene Transcription by a Constitutively Active Mutant of Activating Transcription Factor 2 (ATF2)
- Solvent Isotope Effect on the Reaction Catalysed by the Pyruvate Dehydrogenase Complex from Escherichia coli
- Selective Induction of Liver Parenchymal Cell Heme Oxygenase-1 in Selenium-Deficient Rats
Articles in the same Issue
- Glutathione, Related Enzymology, and Leopold Flohé
- 'Lest I Forget Thee, Glutathione...'
- Glutathione Pathways in the Brain
- The Role of Glutathione Peroxidases in Trypanosomatids
- Cytoprotection against Oxidative Stress and the Regulation of Glutathione Synthesis
- The Parasite-Specific Trypanothione Metabolism of Trypanosoma and Leishmania
- Glutathione – Functions and Metabolism in the Malarial Parasite Plasmodium falciparum
- Oxidative Stress Caused by Inactivation of Glutathione Peroxidase and Adaptive Responses
- Versatility of Selenium Catalysis in PHGPx Unraveled by LC/ESI-MS/MS
- Modulation of the Chymotrypsin-Like Activity of the 20S Proteasome by Intracellular Redox Status: Effects of Glutathione Peroxidase-1 Overexpression and Antioxidant Drugs
- Microflora Trigger Colitis in Mice Deficient in Selenium-Dependent Glutathione Peroxidase and Induce Gpx2 Gene Expression
- Recruitment of the Interleukin-1 Receptor (IL-1RI)-Associated Kinase IRAK to the IL-1RI Is Redox Regulated
- Kinetics and Redox-Sensitive Oligomerisation Reveal Negative Subunit Cooperativity in Tryparedoxin Peroxidase of Trypanosoma brucei brucei
- Testis-Specific Expression of the Nuclear Form of Phospholipid Hydroperoxide Glutathione Peroxidase (PHGPx)
- Selective Recognition of Peptide Sequences by Glutathione Transferases: A Possible Mechanism for Modulation of Cellular Stress-Induced Signaling Pathways
- Biosynthesis of Trypanothione in Trypanosoma brucei brucei
- Transcriptional Regulation of Cytosol and Membrane Alanyl-Aminopeptidase in Human T Cell Subsets
- Regulation of Gene Transcription by a Constitutively Active Mutant of Activating Transcription Factor 2 (ATF2)
- Solvent Isotope Effect on the Reaction Catalysed by the Pyruvate Dehydrogenase Complex from Escherichia coli
- Selective Induction of Liver Parenchymal Cell Heme Oxygenase-1 in Selenium-Deficient Rats
