1
|
Bolduc J, Koruza K, Luo T, Malo Pueyo J, Vo TN, Ezeriņa D, Messens J. Peroxiredoxins wear many hats: Factors that fashion their peroxide sensing personalities. Redox Biol 2021; 42:101959. [PMID: 33895094 PMCID: PMC8113037 DOI: 10.1016/j.redox.2021.101959] [Citation(s) in RCA: 39] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2020] [Revised: 03/07/2021] [Accepted: 03/25/2021] [Indexed: 02/07/2023] Open
Abstract
Peroxiredoxins (Prdxs) sense and assess peroxide levels, and signal through protein interactions. Understanding the role of the multiple structural and post-translational modification (PTM) layers that tunes the peroxiredoxin specificities is still a challenge. In this review, we give a tabulated overview on what is known about human and bacterial peroxiredoxins with a focus on structure, PTMs, and protein-protein interactions. Armed with numerous cellular and atomic level experimental techniques, we look at the future and ask ourselves what is still needed to give us a clearer view on the cellular operating power of Prdxs in both stress and non-stress conditions.
Collapse
Affiliation(s)
- Jesalyn Bolduc
- VIB-VUB Center for Structural Biology, Vlaams Instituut voor Biotechnologie, B-1050, Brussels, Belgium; Brussels Center for Redox Biology, Vrije Universiteit Brussel, B-1050, Brussels, Belgium; Structural Biology Brussels, Vrije Universiteit Brussel, B-1050, Brussels, Belgium
| | - Katarina Koruza
- VIB-VUB Center for Structural Biology, Vlaams Instituut voor Biotechnologie, B-1050, Brussels, Belgium; Brussels Center for Redox Biology, Vrije Universiteit Brussel, B-1050, Brussels, Belgium; Structural Biology Brussels, Vrije Universiteit Brussel, B-1050, Brussels, Belgium
| | - Ting Luo
- VIB-VUB Center for Structural Biology, Vlaams Instituut voor Biotechnologie, B-1050, Brussels, Belgium; Brussels Center for Redox Biology, Vrije Universiteit Brussel, B-1050, Brussels, Belgium; Structural Biology Brussels, Vrije Universiteit Brussel, B-1050, Brussels, Belgium
| | - Julia Malo Pueyo
- VIB-VUB Center for Structural Biology, Vlaams Instituut voor Biotechnologie, B-1050, Brussels, Belgium; Brussels Center for Redox Biology, Vrije Universiteit Brussel, B-1050, Brussels, Belgium; Structural Biology Brussels, Vrije Universiteit Brussel, B-1050, Brussels, Belgium
| | - Trung Nghia Vo
- VIB-VUB Center for Structural Biology, Vlaams Instituut voor Biotechnologie, B-1050, Brussels, Belgium; Brussels Center for Redox Biology, Vrije Universiteit Brussel, B-1050, Brussels, Belgium; Structural Biology Brussels, Vrije Universiteit Brussel, B-1050, Brussels, Belgium
| | - Daria Ezeriņa
- VIB-VUB Center for Structural Biology, Vlaams Instituut voor Biotechnologie, B-1050, Brussels, Belgium; Brussels Center for Redox Biology, Vrije Universiteit Brussel, B-1050, Brussels, Belgium; Structural Biology Brussels, Vrije Universiteit Brussel, B-1050, Brussels, Belgium
| | - Joris Messens
- VIB-VUB Center for Structural Biology, Vlaams Instituut voor Biotechnologie, B-1050, Brussels, Belgium; Brussels Center for Redox Biology, Vrije Universiteit Brussel, B-1050, Brussels, Belgium; Structural Biology Brussels, Vrije Universiteit Brussel, B-1050, Brussels, Belgium.
| |
Collapse
|
2
|
Structural modeling and role of HAX-1 as a positive allosteric modulator of human serine protease HtrA2. Biochem J 2019; 476:2965-2980. [PMID: 31548268 DOI: 10.1042/bcj20190569] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2019] [Revised: 09/18/2019] [Accepted: 09/23/2019] [Indexed: 11/17/2022]
Abstract
HAX-1, a multifunctional protein involved in cell proliferation, calcium homeostasis, and regulation of apoptosis, is a promising therapeutic target. It regulates apoptosis through multiple pathways, understanding of which is limited by the obscurity of its structural details and its intricate interaction with its cellular partners. Therefore, using computational modeling, biochemical, functional enzymology and spectroscopic tools, we predicted the structure of HAX-1 as well as delineated its interaction with one of it pro-apoptotic partner, HtrA2. In this study, three-dimensional structure of HAX-1 was predicted by threading and ab initio tools that were validated using limited proteolysis and fluorescence quenching studies. Our pull-down studies distinctly demonstrate that the interaction of HtrA2 with HAX-1 is directly through its protease domain and not via the conventional PDZ domain. Enzymology studies further depicted that HAX-1 acts as an allosteric activator of HtrA2. This 'allosteric regulation' offers promising opportunities for the specific control and functional modulation of a wide range of biological processes associated with HtrA2. Hence, this study for the first time dissects the structural architecture of HAX-1 and elucidates its role in PDZ-independent activation of HtrA2.
Collapse
|
3
|
Abstract
SIGNIFICANCE Peroxiredoxins (Prxs) are thiol peroxidases with multiple functions in the antioxidant defense and redox signaling network of the cell. Our progressing understanding assigns both local and global significance to plant Prxs, which are grouped in four Prx types. In plants they are localized to the cytosol, mitochondrion, plastid, and nucleus. Antioxidant defense is fundamentally connected to redox signaling, cellular communication, and acclimation. The thiol-disulfide network is central part of the stress sensing and processing response and integrates information input with redox regulation. Recent Advances: Prxs function both as redox sensory system within the network and redox-dependent interactors. The processes directly or indirectly targeted by Prxs include gene expression, post-transcriptional reactions, including translation, post-translational regulation, and switching or tuning of metabolic pathways, and other cell activities. The most advanced knowledge is available for the chloroplast 2-CysPrx wherein recently a solid interactome has been defined. An in silico analysis of protein structure and coexpression reinforces new insights into the 2-CysPrx functionality. CRITICAL ISSUES Up to now, Prxs often have been investigated for local properties of enzyme activity. In vitro and ex vivo work with mutants will reveal the ability of Prxs to interfere with multiple cellular components, including crosstalk with Ca2+-linked signaling pathways, hormone signaling, and protein homeostasis. FUTURE DIRECTIONS Complementation of the Prxs knockout lines with variants that mimic specific states, namely devoid of peroxidase activity, lacking the oligomerization ability, resembling the hyperoxidized decamer, or with truncated C-terminus, should allow dissecting the roles as thiol peroxidase, oxidant, interaction partner, and chaperone. Antioxid. Redox Signal. 28, 609-624.
Collapse
Affiliation(s)
- Michael Liebthal
- Department of Biochemistry and Physiology of Plants, Faculty of Biology, University of Bielefeld , Bielefeld, Germany
| | - Daniel Maynard
- Department of Biochemistry and Physiology of Plants, Faculty of Biology, University of Bielefeld , Bielefeld, Germany
| | - Karl-Josef Dietz
- Department of Biochemistry and Physiology of Plants, Faculty of Biology, University of Bielefeld , Bielefeld, Germany
| |
Collapse
|
4
|
Zurawa-Janicka D, Wenta T, Jarzab M, Skorko-Glonek J, Glaza P, Gieldon A, Ciarkowski J, Lipinska B. Structural insights into the activation mechanisms of human HtrA serine proteases. Arch Biochem Biophys 2017; 621:6-23. [PMID: 28396256 DOI: 10.1016/j.abb.2017.04.004] [Citation(s) in RCA: 44] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2017] [Revised: 04/05/2017] [Accepted: 04/06/2017] [Indexed: 12/21/2022]
Abstract
Human HtrA1-4 proteins belong to the HtrA family of evolutionarily conserved serine proteases and function as important modulators of many physiological processes, including maintenance of mitochondrial homeostasis, cell signaling and apoptosis. Disturbances in their action are linked to severe diseases, including oncogenesis and neurodegeneration. The HtrA1-4 proteins share structural and functional features of other members of the HtrA protein family, however there are several significant differences in structural architecture and mechanisms of action which makes each of them unique. Our goal is to present recent studies regarding human HtrAs. We focus on their physiological functions, structure and regulation, and describe current models of activation mechanisms. Knowledge of molecular basis of the human HtrAs' action is a subject of great interest; it is crucial for understanding their relevance in cellular physiology and pathogenesis as well as for using them as targets in future therapies of diseases such as neurodegenerative disorders and cancer.
Collapse
Affiliation(s)
- Dorota Zurawa-Janicka
- Department of General and Medical Biochemistry, Faculty of Biology, University of Gdansk, Wita Stwosza 59, 80-308 Gdansk, Poland.
| | - Tomasz Wenta
- Department of General and Medical Biochemistry, Faculty of Biology, University of Gdansk, Wita Stwosza 59, 80-308 Gdansk, Poland
| | - Miroslaw Jarzab
- Department of General and Medical Biochemistry, Faculty of Biology, University of Gdansk, Wita Stwosza 59, 80-308 Gdansk, Poland
| | - Joanna Skorko-Glonek
- Department of General and Medical Biochemistry, Faculty of Biology, University of Gdansk, Wita Stwosza 59, 80-308 Gdansk, Poland
| | - Przemyslaw Glaza
- Department of General and Medical Biochemistry, Faculty of Biology, University of Gdansk, Wita Stwosza 59, 80-308 Gdansk, Poland
| | - Artur Gieldon
- Department of Theoretical Chemistry, Faculty of Chemistry, University of Gdansk, Wita Stwosza 63, 80-308 Gdansk, Poland
| | - Jerzy Ciarkowski
- Department of Theoretical Chemistry, Faculty of Chemistry, University of Gdansk, Wita Stwosza 63, 80-308 Gdansk, Poland
| | - Barbara Lipinska
- Department of General and Medical Biochemistry, Faculty of Biology, University of Gdansk, Wita Stwosza 59, 80-308 Gdansk, Poland
| |
Collapse
|
5
|
Cerveau D, Kraut A, Stotz HU, Mueller MJ, Couté Y, Rey P. Characterization of the Arabidopsis thaliana 2-Cys peroxiredoxin interactome. PLANT SCIENCE : AN INTERNATIONAL JOURNAL OF EXPERIMENTAL PLANT BIOLOGY 2016; 252:30-41. [PMID: 27717466 DOI: 10.1016/j.plantsci.2016.07.003] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/29/2016] [Revised: 06/15/2016] [Accepted: 07/09/2016] [Indexed: 06/06/2023]
Abstract
Peroxiredoxins are ubiquitous thiol-dependent peroxidases for which chaperone and signaling roles have been reported in various types of organisms in recent years. In plants, the peroxidase function of the two typical plastidial 2-Cys peroxiredoxins (2-Cys PRX A and B) has been highlighted while the other functions, particularly in ROS-dependent signaling pathways, are still elusive notably due to the lack of knowledge of interacting partners. Using an ex vivo approach based on co-immunoprecipitation of leaf extracts from Arabidopsis thaliana wild-type and mutant plants lacking 2-Cys PRX expression followed by mass spectrometry-based proteomics, 158 proteins were found associated with 2-Cys PRXs. Already known partners like thioredoxin-related electron donors (Chloroplastic Drought-induced Stress Protein of 32kDa, Atypical Cysteine Histidine-rich Thioredoxin 2) and enzymes involved in chlorophyll synthesis (Protochlorophyllide OxidoReductase B) or carbon metabolism (Fructose-1,6-BisPhosphatase) were identified, validating the relevance of the approach. Bioinformatic and bibliographic analyses allowed the functional classification of the identified proteins and revealed that more than 40% are localized in plastids. The possible roles of plant 2-Cys PRXs in redox signaling pathways are discussed in relation with the functions of the potential partners notably those involved in redox homeostasis, carbon and amino acid metabolisms as well as chlorophyll biosynthesis.
Collapse
Affiliation(s)
- Delphine Cerveau
- CEA, DRF, BIAM, Laboratoire d'Ecophysiologie Moléculaire des Plantes, Saint-Paul-lez-Durance, F-13108, France; CNRS, UMR 7265 Biologie Végétale & Microbiologie Environnementale, Saint-Paul-lez-Durance, F-13108, France; Aix-Marseille Université, Saint-Paul-lez-Durance, F-13108, France
| | - Alexandra Kraut
- Univ. Grenoble Alpes, Institut de Biosciences et Biotechnologies de Grenoble, Grenoble, U1038, F-38000, France; CEA, BIG-BGE, Grenoble, F-38000, France; INSERM, U1038, Grenoble, F-38000, France
| | - Henrik U Stotz
- Julius-von-Sachs-Institute of Biosciences, Biocenter, Pharmaticeutical Biology, University of Wuerzburg, D-97082, Wuerzburg, Germany
| | - Martin J Mueller
- Julius-von-Sachs-Institute of Biosciences, Biocenter, Pharmaticeutical Biology, University of Wuerzburg, D-97082, Wuerzburg, Germany
| | - Yohann Couté
- Univ. Grenoble Alpes, Institut de Biosciences et Biotechnologies de Grenoble, Grenoble, U1038, F-38000, France; CEA, BIG-BGE, Grenoble, F-38000, France; INSERM, U1038, Grenoble, F-38000, France
| | - Pascal Rey
- CEA, DRF, BIAM, Laboratoire d'Ecophysiologie Moléculaire des Plantes, Saint-Paul-lez-Durance, F-13108, France; CNRS, UMR 7265 Biologie Végétale & Microbiologie Environnementale, Saint-Paul-lez-Durance, F-13108, France; Aix-Marseille Université, Saint-Paul-lez-Durance, F-13108, France.
| |
Collapse
|
6
|
Vavougios GD, Solenov EI, Hatzoglou C, Baturina GS, Katkova LE, Molyvdas PA, Gourgoulianis KI, Zarogiannis SG. Computational genomic analysis of PARK7 interactome reveals high BBS1 gene expression as a prognostic factor favoring survival in malignant pleural mesothelioma. Am J Physiol Lung Cell Mol Physiol 2015; 309:L677-86. [PMID: 26254420 DOI: 10.1152/ajplung.00051.2015] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2015] [Accepted: 08/03/2015] [Indexed: 01/04/2023] Open
Abstract
The aim of our study was to assess the differential gene expression of Parkinson protein 7 (PARK7) interactome in malignant pleural mesothelioma (MPM) using data mining techniques to identify novel candidate genes that may play a role in the pathogenicity of MPM. We constructed the PARK7 interactome using the ConsensusPathDB database. We then interrogated the Oncomine Cancer Microarray database using the Gordon Mesothelioma Study, for differential gene expression of the PARK7 interactome. In ConsensusPathDB, 38 protein interactors of PARK7 were identified. In the Gordon Mesothelioma Study, 34 of them were assessed out of which SUMO1, UBC3, KIAA0101, HDAC2, DAXX, RBBP4, BBS1, NONO, RBBP7, HTRA2, and STUB1 were significantly overexpressed whereas TRAF6 and MTA2 were significantly underexpressed in MPM patients (network 2). Furthermore, Kaplan-Meier analysis revealed that MPM patients with high BBS1 expression had a median overall survival of 16.5 vs. 8.7 mo of those that had low expression. For validation purposes, we performed a meta-analysis in Oncomine database in five sarcoma datasets. Eight network 2 genes (KIAA0101, HDAC2, SUMO1, RBBP4, NONO, RBBP7, HTRA2, and MTA2) were significantly differentially expressed in an array of 18 different sarcoma types. Finally, Gene Ontology annotation enrichment analysis revealed significant roles of the PARK7 interactome in NuRD, CHD, and SWI/SNF protein complexes. In conclusion, we identified 13 novel genes differentially expressed in MPM, never reported before. Among them, BBS1 emerged as a novel predictor of overall survival in MPM. Finally, we identified that PARK7 interactome is involved in novel pathways pertinent in MPM disease.
Collapse
Affiliation(s)
- Georgios D Vavougios
- Department of Respiratory Medicine, Faculty of Medicine, University of Thessaly, BIOPOLIS, Larissa, Greece
| | - Evgeniy I Solenov
- Institute of Cytology and Genetics of the Siberian Branch of the Russian Academy of Sciences, Novosibirsk, Russia; Novosibirsk State University, Novosibirsk, Russia; and
| | - Chrissi Hatzoglou
- Department of Respiratory Medicine, Faculty of Medicine, University of Thessaly, BIOPOLIS, Larissa, Greece; Department of Physiology, Faculty of Medicine, University of Thessaly, BIOPOLIS, Larissa, Greece
| | - Galina S Baturina
- Institute of Cytology and Genetics of the Siberian Branch of the Russian Academy of Sciences, Novosibirsk, Russia
| | - Liubov E Katkova
- Institute of Cytology and Genetics of the Siberian Branch of the Russian Academy of Sciences, Novosibirsk, Russia
| | - Paschalis Adam Molyvdas
- Department of Physiology, Faculty of Medicine, University of Thessaly, BIOPOLIS, Larissa, Greece
| | | | - Sotirios G Zarogiannis
- Department of Respiratory Medicine, Faculty of Medicine, University of Thessaly, BIOPOLIS, Larissa, Greece; Department of Physiology, Faculty of Medicine, University of Thessaly, BIOPOLIS, Larissa, Greece
| |
Collapse
|
7
|
Pruefer FG, Lizarraga F, Maldonado V, Melendez-Zajgla J. Participation of Omi Htra2 Serine-Protease Activity in the Apoptosis Induced by Cisplatin on SW480 Colon Cancer Cells. J Chemother 2013; 20:348-54. [DOI: 10.1179/joc.2008.20.3.348] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022]
|
8
|
Rhee SG, Woo HA. Multiple functions of peroxiredoxins: peroxidases, sensors and regulators of the intracellular messenger H₂O₂, and protein chaperones. Antioxid Redox Signal 2011; 15:781-94. [PMID: 20919930 DOI: 10.1089/ars.2010.3393] [Citation(s) in RCA: 335] [Impact Index Per Article: 25.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Peroxiredoxins (Prxs) are a family of peroxidases that reduce peroxides, with a conserved cysteine residue (the peroxidatic Cys) serving as the site of oxidation by peroxides. Peroxides oxidize the peroxidatic Cys-SH to Cys-SOH, which then reacts with another cysteine residue (typically the resolving Cys [C(R)]) to form a disulfide that is subsequently reduced by an appropriate electron donor. On the basis of the location or absence of the C(R), Prxs are classified into 2-Cys, atypical 2-Cys, and 1-Cys Prx subfamilies. In addition to their peroxidase activity, members of the 2-Cys Prx subfamily appear to serve as peroxide sensors for other proteins and as molecular chaperones. During catalysis, the peroxidatic Cys-SOH of 2-Cys Prxs is occasionally further oxidized to Cys-SO(2)H before disulfide formation, resulting in inactivation of peroxidase activity. This hyperoxidation, which is reversed by the ATP-dependent enzyme sulfiredoxin, modulates the sensor and chaperone functions of 2-Cys Prxs. The peroxidase activity of 2-Cys Prxs is extensively regulated via tyrosine and threonine phosphorylation, which allows modulation of the local concentration of the intracellular messenger H(2)O(2). Finally, 2-Cys Prxs interact with a variety of proteins, with such interaction having been shown to modulate the function of the binding partners in a reciprocal manner.
Collapse
Affiliation(s)
- Sue Goo Rhee
- Division of Life and Pharmaceutical Sciences, Ewha Womans University, Seoul, Korea.
| | | |
Collapse
|
9
|
Lowther WT, Haynes AC. Reduction of cysteine sulfinic acid in eukaryotic, typical 2-Cys peroxiredoxins by sulfiredoxin. Antioxid Redox Signal 2011; 15:99-109. [PMID: 20712415 PMCID: PMC3110103 DOI: 10.1089/ars.2010.3564] [Citation(s) in RCA: 81] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
The eukaryotic, typical 2-Cys peroxiredoxins (Prxs) are inactivated by hyperoxidation of one of their active-site cysteine residues to cysteine sulfinic acid. This covalent modification is thought to enable hydrogen peroxide-mediated cell signaling and to act as a functional switch between a peroxidase and a high-molecular-weight chaperone. Moreover, hyperoxidation has been implicated in a variety of disease states associated with oxidative stress, including cancer and aging-associated pathologies. A repair enzyme, sulfiredoxin (Srx), reduces the sulfinic acid moiety by using an unusual ATP-dependent mechanism. In this process, the Prx molecule undergoes dramatic structural rearrangements to facilitate repair. Structural, kinetic, mutational, and mass spectrometry-based approaches have been used to dissect the molecular basis for Srx catalysis. The available data support the direct formation of Cys sulfinic acid phosphoryl ester and protein-based thiosulfinate intermediates. This review discusses the role of Srx in the reversal of Prx hyperoxidation, the questions raised concerning the reductant required for human Srx regeneration, and the deglutathionylating activity of Srx. The complex interplay between Prx hyperoxidation, other forms of Prx covalent modification, and the oligomeric state also are discussed.
Collapse
Affiliation(s)
- W Todd Lowther
- Center for Structural Biology, Department of Biochemistry, Wake Forest University School of Medicine, Winston-Salem, North Carolina, USA
| | | |
Collapse
|
10
|
Fourquet S, Huang ME, D'Autreaux B, Toledano MB. The dual functions of thiol-based peroxidases in H2O2 scavenging and signaling. Antioxid Redox Signal 2008; 10:1565-76. [PMID: 18498222 DOI: 10.1089/ars.2008.2049] [Citation(s) in RCA: 121] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Thiol-based peroxidases consist of the peroxiredoxins (Prx) and the related glutathione peroxidase (GPx)-like enzymes. Their catalytic function is to reduce peroxides by using the reactivity of the cysteine residue, and their presumed primary physiologic role is to protect living organisms from peroxide toxicity. However, as peroxide-metabolizing enzymes, they also regulate hydrogen peroxide (H2O2) signaling. We review here enzymatic and biochemical attributes of thiol peroxidases that specify both distinctive peroxide-scavenging functions and the property of regulating H2O2 signaling. We then discuss possible thiol peroxidase physiologic functions, based on selected observations made in microorganisms and mammals.
Collapse
Affiliation(s)
- Simon Fourquet
- CEA, DSV, IBITECS, Laboratoire Stress Oxydants et Cancer, CEA-Saclay, Gif-sur-Yvette France
| | | | | | | |
Collapse
|
11
|
Structure of the sulphiredoxin-peroxiredoxin complex reveals an essential repair embrace. Nature 2008; 451:98-101. [PMID: 18172504 DOI: 10.1038/nature06415] [Citation(s) in RCA: 119] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2007] [Accepted: 10/24/2007] [Indexed: 11/09/2022]
Abstract
Typical 2-Cys peroxiredoxins (Prxs) have an important role in regulating hydrogen peroxide-mediated cell signalling. In this process, Prxs can become inactivated through the hyperoxidation of an active site Cys residue to Cys sulphinic acid. The unique repair of this moiety by sulphiredoxin (Srx) restores peroxidase activity and terminates the signal. The hyperoxidized form of Prx exists as a stable decameric structure with each active site buried. Therefore, it is unclear how Srx can access the sulphinic acid moiety. Here we present the 2.6 A crystal structure of the human Srx-PrxI complex. This complex reveals the complete unfolding of the carboxy terminus of Prx, and its unexpected packing onto the backside of Srx away from the Srx active site. Binding studies and activity analyses of site-directed mutants at this interface show that the interaction is required for repair to occur. Moreover, rearrangements in the Prx active site lead to a juxtaposition of the Prx Gly-Gly-Leu-Gly and Srx ATP-binding motifs, providing a structural basis for the first step of the catalytic mechanism. The results also suggest that the observed interactions may represent a common mode for other proteins to bind to Prxs.
Collapse
|