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Gao Q, Grzyb K, Gamon LF, Ogilby PR, Pędziński T, Davies MJ. The structure of model and peptide disulfides markedly affects their reactivity and products formed with singlet oxygen. Free Radic Biol Med 2023; 207:320-329. [PMID: 37633403 DOI: 10.1016/j.freeradbiomed.2023.08.024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/10/2023] [Revised: 08/22/2023] [Accepted: 08/23/2023] [Indexed: 08/28/2023]
Abstract
Disulfide bonds are critical structural elements in proteins and stabilize folded structures. Modification of these linkages is associated with a loss of structure and function. Previous studies have reported large variations in the rate of disulfide oxidation by hypohalous acids, due to stabilization of reaction intermediates. In this study we hypothesized that considerable variation (and hence selective oxidation) would occur with singlet oxygen (1O2), a key intermediate in photo-oxidation reactions. The kinetics of disulfide-mediated 1O2 removal were monitored using the time-resolved 1270 nm phosphorescence of 1O2. Stern-Volmer plots of these data showed a large variation (∼103) in the quenching rate constants kq (from 2 × 107 for α-lipoic acid to 3.6 × 104 M-1s-1 for cystamine). The time course of disulfide loss and product formation (determined by LC-MS) support a role for 1O2, with mono- and di-oxygenated products detected. Elevated levels of these latter species were generated in D2O- compared to H2O buffers, which is consistent with solvent effects on the 1O2 lifetime. These data are interpreted in terms of the intermediacy of a zwitterion [-S+(OO-)-S-], which either isomerizes to a thiosulfonate [-S(O)2-S-] or reacts with another parent molecule to give two thiosulfinates [-S(O)-S-]. The variation in quenching rates and product formation are ascribed to zwitterion stabilization by neighboring, or remote, lone pairs of electrons. These data suggest that some disulfides, including some present within or attached to proteins (e.g., α-lipoic acid), may be selectively modified, and undergo subsequent cleavage, with adverse effects on protein structure and function.
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Affiliation(s)
- Qing Gao
- Department of Biomedical Sciences, Panum Institute, University of Copenhagen, Copenhagen, 2200, Denmark
| | - Katarzyna Grzyb
- Faculty of Chemistry, Adam Mickiewicz University, Uniwersytetu Poznanskiego 8, 61-614, Poznań, Poland
| | - Luke F Gamon
- Department of Biomedical Sciences, Panum Institute, University of Copenhagen, Copenhagen, 2200, Denmark
| | - Peter R Ogilby
- Department of Chemistry, Aarhus University, DK-8000, Aarhus, Denmark
| | - Tomasz Pędziński
- Faculty of Chemistry, Adam Mickiewicz University, Uniwersytetu Poznanskiego 8, 61-614, Poznań, Poland
| | - Michael J Davies
- Department of Biomedical Sciences, Panum Institute, University of Copenhagen, Copenhagen, 2200, Denmark.
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Pradhan R, Panigrahi S, Sahu PK. Conformational Search for the Building Block of Proteins Based on the Gradient Gravitational Search Algorithm (ConfGGS) Using Force Fields: CHARMM, AMBER, and OPLS-AA. J Chem Inf Model 2023; 63:670-690. [PMID: 36625780 DOI: 10.1021/acs.jcim.2c01398] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Proteins are linear polymers built from a repertoire of 20 different amino acids, which are considered building blocks of proteins. The diversity and versatility of these 20 building blocks with regard to their conformations are key to adopting three-dimensional structures that facilitate proteins to undergo important mechanistic biological processes in living systems. The present investigation reports a conformational search of 20 different amino acids, building blocks of proteins, using three different force fields, CHARMM, AMBER, and OPLS-AA, implemented in the gradient gravitational search algorithm. The search technique (ConfGGS) includes the contribution from both bonded and nonbonded terms using Cartesian coordinates. The efficiency of such conformational searches has also been compared with other optimization algorithms: DE/Best, DE/Rand, and PSO algorithms with respect to computational time and accuracy based on the minimum number of iteration steps and computed lowest mean absolute error (MAE) and mean standard deviation (MSD) values for dihedral angles of respective near-optimal structures. Moreover, the ConfGGS technique has also been extended to an ordered protein fragment (PQITL) extracted from HIV-1 protease (PDB ID: 1YTH), an intrinsically disordered protein fragment, i.e., an amyloid-forming segment (AVVTGVTAV), from the NAC domain of Parkinson's disease protein α-synuclein, residues 69-77 (PDB ID: 4RIK), the experimental NMR atomic-resolution structure of α-synuclein fibrils (PDB ID: 2N0A), and a disulfide bond-containing protein fragment sequence (PCYGWPVCY), residues 59-67 (PDB ID: 6Y4F) toward structure prediction as a close homologue compared with experimental accuracy, using the CHARMM force field. The MolProbity validation results for the protein fragment (PQITL) obtained by ConfGGS/CHARMM are in better agreement with the native protein fragment structure of HIV-1 protease (PDB ID: 1YTH). Furthermore, the computed results have also been compared with the coordinates obtained from the AlphaFold network.
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Affiliation(s)
- Rojalin Pradhan
- Computational Modeling Research Laboratory, School of Chemistry (Autonomous), Sambalpur University, Jyoti Vihar, Burla768019, India
| | - Sibarama Panigrahi
- Computational Modeling Research Laboratory, School of Chemistry (Autonomous), Sambalpur University, Jyoti Vihar, Burla768019, India
- Department of Computer Science and Engineering, Sambalpur University Institute of Information Technology, Jyoti Vihar, Burla768019, India
| | - Prabhat K Sahu
- Computational Modeling Research Laboratory, School of Chemistry (Autonomous), Sambalpur University, Jyoti Vihar, Burla768019, India
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3
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Xu S, Wang Y, Jiang Y, Han C, Qin Q, Wei S. Functional analysis of the cystatin A gene response to SGIV infection in orange-spotted grouper, Epinephelus coioides. DEVELOPMENTAL AND COMPARATIVE IMMUNOLOGY 2022; 136:104502. [PMID: 35940384 DOI: 10.1016/j.dci.2022.104502] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/29/2022] [Revised: 07/31/2022] [Accepted: 07/31/2022] [Indexed: 06/15/2023]
Abstract
Cystatin A (CyA), an inhibitor of cysteine protease, was widely studied in immune defense and cancer therapy. However, the function of CyA and its potential molecular mechanism during virus infection in fish remain unknown. In our study, we cloned the open reading frame (ORF) of CyA homology from orange-spotted grouper (Ec-CyA) consisting of 303 nucleotides and encoding a 101-amino acid protein. Ec-CyA included two conserved sequences containing one N-terminal glycine fragment and one QXVXG sequence (48aa-52aa) without the signal peptide. Tissue distribution analysis showed that Ec-CyA was highly expressed in spleen and head kidney. Moreover, further analysis indicated that the expression of Ec-CyA increased during SGIV simulation in grouper spleen (GS) cells. Subcellular localization assay demonstrated that Ec-CyA was mainly distributed in cytoplasm in GS cells. Overexpressed Ec-CyA promoted the mRNA level of viral genes MCP, VP19 and LITAF. Meanwhile, SGIV-induced apoptosis in fat head minnow (FHM) cells was facilitated, as well as the activation of caspase-3/7, caspase-9. In addition, Ec-CyA overexpression down-regulated the expression of interferon (IFN) related molecules including ISG15, IFN, IRF3, MAVS, MyD88, TRAF6 and up-regulated proinflammatory factors such as IL-1β, IL-8 and TNF-α. At the same time, Ec-CyA-overexpressing inhibited the activity of IFN and ISRE promoter, but induced NF-κB promoter activity by luciferase reporter gene assay. In summary, our findings suggested that Ec-CyA was involved in innate immune response and played a key role in DNA virus infection.
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Affiliation(s)
- Suifeng Xu
- College of Marine Sciences, South China Agricultural University, Guangdong Laboratory for Lingnan Modern Agriculture, Guangzhou, 510642, China
| | - Yuexuan Wang
- College of Marine Sciences, South China Agricultural University, Guangdong Laboratory for Lingnan Modern Agriculture, Guangzhou, 510642, China
| | - Yunxiang Jiang
- College of Marine Sciences, South China Agricultural University, Guangdong Laboratory for Lingnan Modern Agriculture, Guangzhou, 510642, China
| | - Chengzong Han
- College of Marine Sciences, South China Agricultural University, Guangdong Laboratory for Lingnan Modern Agriculture, Guangzhou, 510642, China
| | - Qiwei Qin
- College of Marine Sciences, South China Agricultural University, Guangdong Laboratory for Lingnan Modern Agriculture, Guangzhou, 510642, China; Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), 528478, China; Laboratory for Marine Biology and Biotechnology, Qingdao National Laboratory for Marine Science and Technology, Qingdao, 266000, China.
| | - Shina Wei
- College of Marine Sciences, South China Agricultural University, Guangdong Laboratory for Lingnan Modern Agriculture, Guangzhou, 510642, China.
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Xu S, Wang Y, Han C, Jiang Y, Qin Q, Wei S. Functional analysis of the Cystatin F gene response to SGIV infection in orange-spotted grouper, Epinephelus coioides. FISH & SHELLFISH IMMUNOLOGY 2022; 130:43-52. [PMID: 36084885 DOI: 10.1016/j.fsi.2022.09.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/12/2022] [Revised: 08/18/2022] [Accepted: 09/01/2022] [Indexed: 06/15/2023]
Abstract
Cystatin F (CyF), an inhibitor of cysteine protease, was widely studied in immune defense and cancer therapy. However, the function of CyF and its latent molecular mechanism during virus infection in fish remain vacant. In our research, we cloned the open reading frame (ORF) of CyF homology from orange-spotted grouper (Ec-CyF) consisting of 342 nucleotides and encoding a 114-amino acid protein. Ec-CyF included two cystatins family sequences containing one KXVXG sequence without the signal peptide, and a hairpin ring containing proline and tryptophan (PW). Tissue distribution analysis indicated that Ec-CyF was highly expressed in spleen and head kidney. Besides, further analysis showed that the expression of Ec-CyF increased during SGIV infection in grouper spleen (GS) cells. Subcellular localization assay demonstrated that Ec-CyF was mainly distributed in cytoplasm in GS cells. Overexpressed Ec-CyF demoted the mRNA level of viral genes MCP, VP19 and LITAF. Meanwhile, SGIV-induced apoptosis in fat head minnow (FHM) cells was impeded, as well as the restraint of caspase 3/7 and caspase 8. In addition, Ec-CyF overexpression up-regulated the expression of IFN related molecules including ISG15, IFN, IFP35, IRF3, IRF7, MYD88 and down-regulated proinflammatory factors such as IL-1β, IL-8 and TNF-α. At the same time, Ec-CyF-overexpressing increased the activity of IFN3 and ISRE promoter, but impeded NF-κB promoter activity by luciferase reporter gene assay. In summary, our findings suggested that Ec-CyF was involved in innate immunity response and played a key role in DNA virus infection.
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Affiliation(s)
- Suifeng Xu
- College of Marine Sciences, South China Agricultural University, Guangdong Laboratory for Lingnan Modern Agriculture, Guangzhou, 510642, China
| | - Yuexuan Wang
- College of Marine Sciences, South China Agricultural University, Guangdong Laboratory for Lingnan Modern Agriculture, Guangzhou, 510642, China
| | - Chengzong Han
- College of Marine Sciences, South China Agricultural University, Guangdong Laboratory for Lingnan Modern Agriculture, Guangzhou, 510642, China
| | - Yunxiang Jiang
- College of Marine Sciences, South China Agricultural University, Guangdong Laboratory for Lingnan Modern Agriculture, Guangzhou, 510642, China
| | - Qiwei Qin
- College of Marine Sciences, South China Agricultural University, Guangdong Laboratory for Lingnan Modern Agriculture, Guangzhou, 510642, China; Southern Marine Science and Engineering Guangdong Laboratory, Zhuhai, 528478, China; Laboratory for Marine Biology and Biotechnology, Qingdao National Laboratory for Marine Science and Technology, Qingdao, 266000, China.
| | - Shina Wei
- College of Marine Sciences, South China Agricultural University, Guangdong Laboratory for Lingnan Modern Agriculture, Guangzhou, 510642, China.
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Arsiccio A, Metcalfe C, Pisano R, Raut S, Coxon C. A proximity-based in silico approach to identify redox-labile disulfide bonds: The example of FVIII. PLoS One 2022; 17:e0262409. [PMID: 35130281 PMCID: PMC8820644 DOI: 10.1371/journal.pone.0262409] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2020] [Accepted: 12/27/2021] [Indexed: 01/04/2023] Open
Abstract
Allosteric disulfide bonds permit highly responsive, transient 'switch-like' properties that are ideal for processes like coagulation and inflammation that require rapid and localised responses to damage or injury. Haemophilia A (HA) is a rare bleeding disorder managed with exogenous coagulation factor(F) VIII products. FVIII has eight disulfide bonds and is known to be redox labile, but it is not known how reduction/oxidation affects the structure-function relationship, or its immunogenicity-a serious complication for 30% severe HA patients. Understanding how redox-mediated changes influence FVIII can inform molecular engineering strategies aimed at improving activity and stability, and reducing immunogenicity. FVIII is a challenging molecule to work with owing to its poor expression and instability so, in a proof-of-concept study, we used molecular dynamics (MD) to identify which disulfide bonds were most likely to be reduced and how this would affect structure/function; results were then experimentally verified. MD identified Cys1899-Cys1903 disulfide as the most likely to undergo reduction based on energy and proximity criteria. Further MD suggested this reduction led to a more open conformation. Here we present our findings and highlight the value of MD approaches.
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Affiliation(s)
- Andrea Arsiccio
- Department of Applied Science and Technology, Politecnico di Torino, Torino, Italy
| | - Clive Metcalfe
- National Institute for Biological Standards and Control, Hertfordshire, United Kingdom
| | - Roberto Pisano
- Department of Applied Science and Technology, Politecnico di Torino, Torino, Italy
| | - Sanj Raut
- National Institute for Biological Standards and Control, Hertfordshire, United Kingdom
| | - Carmen Coxon
- National Institute for Biological Standards and Control, Hertfordshire, United Kingdom
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6
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Fuentes-Lemus E, Hägglund P, López-Alarcón C, Davies MJ. Oxidative Crosslinking of Peptides and Proteins: Mechanisms of Formation, Detection, Characterization and Quantification. Molecules 2021; 27:15. [PMID: 35011250 PMCID: PMC8746199 DOI: 10.3390/molecules27010015] [Citation(s) in RCA: 33] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2021] [Revised: 12/17/2021] [Accepted: 12/18/2021] [Indexed: 12/14/2022] Open
Abstract
Covalent crosslinks within or between proteins play a key role in determining the structure and function of proteins. Some of these are formed intentionally by either enzymatic or molecular reactions and are critical to normal physiological function. Others are generated as a consequence of exposure to oxidants (radicals, excited states or two-electron species) and other endogenous or external stimuli, or as a result of the actions of a number of enzymes (e.g., oxidases and peroxidases). Increasing evidence indicates that the accumulation of unwanted crosslinks, as is seen in ageing and multiple pathologies, has adverse effects on biological function. In this article, we review the spectrum of crosslinks, both reducible and non-reducible, currently known to be formed on proteins; the mechanisms of their formation; and experimental approaches to the detection, identification and characterization of these species.
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Affiliation(s)
- Eduardo Fuentes-Lemus
- Department of Biomedical Sciences, Panum Institute, University of Copenhagen, 2200 Copenhagen, Denmark; (E.F.-L.); (P.H.)
| | - Per Hägglund
- Department of Biomedical Sciences, Panum Institute, University of Copenhagen, 2200 Copenhagen, Denmark; (E.F.-L.); (P.H.)
| | - Camilo López-Alarcón
- Departamento de Química Física, Facultad de Química y de Farmacia, Pontificia Universidad Catolica de Chile, Santiago 7820436, Chile;
| | - Michael J. Davies
- Department of Biomedical Sciences, Panum Institute, University of Copenhagen, 2200 Copenhagen, Denmark; (E.F.-L.); (P.H.)
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7
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Li C, Ban X, Zhang Y, Gu Z, Hong Y, Cheng L, Tang X, Li Z. Rational Design of Disulfide Bonds for Enhancing the Thermostability of the 1,4-α-Glucan Branching Enzyme from Geobacillus thermoglucosidans STB02. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2020; 68:13791-13797. [PMID: 33166453 DOI: 10.1021/acs.jafc.0c04798] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Disulfide bonds play crucial roles in thermostabilization, recognition, or activation of proteins. They are vital in maintaining the respective conformations of globular structures, thereby enhancing thermostability. Bioinformatic approaches provide practical strategies to build disulfide bonds based on structural information. We constructed nine mutants by rational analysis of the 1,4-α-glucan branching enzyme (EC 2.4.1.18) from Geobacillus thermoglucosidans STB02, which catalyzes the synthesis of α-1,6-glucosidic bonds by acting on α-(1,4) and/or α-(1,6) glucosidic linkages. Four of the mutations enhanced thermostability, and five of them had adverse or negligible effects on stability. Circular dichroism spectra and intrinsic fluorescence analysis showed that introducing disulfide bonds might only affect secondary structures. The results also demonstrated that the distances of Cα carbons and thiol groups, as well as the sequence between the two cysteines, need to be considered when designing disulfide bonds.
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Affiliation(s)
- Caiming Li
- School of Food Science and Technology, Jiangnan University, Wuxi 214122, China
- Collaborative Innovation Center of Food Safety and Quality Control, Jiangnan University, Wuxi 214122, China
- USDA, Agricultural Research Service, WRRC, 800 Buchanan Street, Albany, California 94710, United States
| | - Xiaofeng Ban
- School of Food Science and Technology, Jiangnan University, Wuxi 214122, China
| | - Yuzhu Zhang
- USDA, Agricultural Research Service, WRRC, 800 Buchanan Street, Albany, California 94710, United States
| | - Zhengbiao Gu
- State Key Laboratory of Food Science and Technology, Jiangnan University, Wuxi 214122, China
- School of Food Science and Technology, Jiangnan University, Wuxi 214122, China
- Collaborative Innovation Center of Food Safety and Quality Control, Jiangnan University, Wuxi 214122, China
| | - Yan Hong
- School of Food Science and Technology, Jiangnan University, Wuxi 214122, China
- Collaborative Innovation Center of Food Safety and Quality Control, Jiangnan University, Wuxi 214122, China
| | - Li Cheng
- School of Food Science and Technology, Jiangnan University, Wuxi 214122, China
- Collaborative Innovation Center of Food Safety and Quality Control, Jiangnan University, Wuxi 214122, China
| | - Xiaoshu Tang
- School of Food Science and Technology, Jiangnan University, Wuxi 214122, China
- National Engineering Research Center for Functional Food, Wuxi 214122, China
| | - Zhaofeng Li
- State Key Laboratory of Food Science and Technology, Jiangnan University, Wuxi 214122, China
- School of Food Science and Technology, Jiangnan University, Wuxi 214122, China
- Collaborative Innovation Center of Food Safety and Quality Control, Jiangnan University, Wuxi 214122, China
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Horváth D, Taricska N, Keszei E, Stráner P, Farkas V, Tóth GK, Perczel A. Compactness of Protein Folds Alters Disulfide-Bond Reducibility by Three Orders of Magnitude: A Comprehensive Kinetic Case Study on the Reduction of Differently Sized Tryptophan Cage Model Proteins. Chembiochem 2019; 21:681-695. [PMID: 31475422 PMCID: PMC7079008 DOI: 10.1002/cbic.201900470] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2019] [Indexed: 12/12/2022]
Abstract
A new approach to monitor disulfide-bond reduction in the vicinity of aromatic cluster(s) has been derived by using the near-UV range (λ=266-293 nm) of electronic circular dichroism (ECD) spectra. By combining the results from NMR and ECD spectroscopy, the 3D fold characteristics and associated reduction rate constants (k) of E19_SS, which is a highly thermostable, disulfide-bond reinforced 39-amino acid long exenatide mimetic, and its N-terminally truncated derivatives have been determined under different experimental conditions. Single disulfide bond reduction of the E19_SS model (with an 18-fold excess of tris(2-carboxyethyl)phosphine, pH 7, 37 °C) takes hours, which is 20-30 times longer than that expected, and thus, would not reach completion by applying commonly used reduction protocols. It is found that structural, steric, and electrostatic factors influence the reduction rate, resulting in orders of magnitude differences in reduction half-lives (900>t1/2 >1 min) even for structurally similar, well-folded derivatives of a small model protein.
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Affiliation(s)
- Dániel Horváth
- Laboratory of Structural Chemistry and Biology and, MTA-ELTE Protein Modeling Research Group at the Institute of Chemistry, Eötvös Loránd University, 112, P. O. Box 32, 1518, Budapest, Hungary
| | - Nóra Taricska
- Laboratory of Structural Chemistry and Biology and, MTA-ELTE Protein Modeling Research Group at the Institute of Chemistry, Eötvös Loránd University, 112, P. O. Box 32, 1518, Budapest, Hungary
| | - Ernő Keszei
- Chemical Kinetics Laboratory, Institute of Chemistry, Eötvös Loránd University, 112, P. O. Box 32, 1518, Budapest, Hungary
| | - Pál Stráner
- Laboratory of Structural Chemistry and Biology and, MTA-ELTE Protein Modeling Research Group at the Institute of Chemistry, Eötvös Loránd University, 112, P. O. Box 32, 1518, Budapest, Hungary
| | - Viktor Farkas
- Laboratory of Structural Chemistry and Biology and, MTA-ELTE Protein Modeling Research Group at the Institute of Chemistry, Eötvös Loránd University, 112, P. O. Box 32, 1518, Budapest, Hungary
| | - Gábor K Tóth
- Department of Medical Chemistry, Faculty of General Medicine, University of Szeged, Szeged Dóm tér 8, H-6720, Szeged, Hungary
| | - András Perczel
- Laboratory of Structural Chemistry and Biology and, MTA-ELTE Protein Modeling Research Group at the Institute of Chemistry, Eötvös Loránd University, 112, P. O. Box 32, 1518, Budapest, Hungary
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Solecka-Witulska BA, Weise C, Kannicht C. Mass Spectrometry-Based Method for Detection and Identification of Free Thiol Groups in Proteins. Methods Mol Biol 2019; 1934:179-189. [PMID: 31256380 DOI: 10.1007/978-1-4939-9055-9_12] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/30/2023]
Abstract
Many proteins contain free sulfhydryl groups which can be involved in a variety of biochemical reactions. Reactive thiol groups can either reside within the active center of oxidoreductases or represent a part of a thiol-based redox switch in proteins. Therefore, the exact position of a free sulfhydryl within a protein is mostly very important.This chapter describes a mass spectrometry-based method to determine the location of protein sulfhydryl groups exemplary shown for a synthetic decapeptide and the plasma glycoprotein von Willebrand factor (VWF). We outline (1) labeling of free sulfhydryl groups, (2) enrichment of labeled peptides, and (3) detection and identification of labeled peptides by mass spectrometry.
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Affiliation(s)
| | - Christoph Weise
- Institute of Chemistry and Biochemistry, Freie Universität Berlin, Berlin, Germany
| | - Christoph Kannicht
- Recombinant Research and Development, Octapharma Biopharmaceuticals GmbH, Heidelberg, Germany
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10
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Zhang D, Fourie-O’Donohue A, Dragovich PS, Pillow TH, Sadowsky JD, Kozak KR, Cass RT, Liu L, Deng Y, Liu Y, Hop CE, Khojasteh SC. Catalytic Cleavage of Disulfide Bonds in Small Molecules and Linkers of Antibody–Drug Conjugates. Drug Metab Dispos 2019; 47:1156-1163. [DOI: 10.1124/dmd.118.086132] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2018] [Accepted: 05/07/2019] [Indexed: 12/11/2022] Open
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Controlling the dynamics of the Nek2 leucine zipper by engineering of "kinetic" disulphide bonds. PLoS One 2019; 14:e0210352. [PMID: 30707691 PMCID: PMC6358272 DOI: 10.1371/journal.pone.0210352] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2018] [Accepted: 12/20/2018] [Indexed: 12/25/2022] Open
Abstract
Nek2 is a dimeric serine/ threonine protein kinase that belongs to the family of NIMA-related kinases (Neks). Its N-terminal catalytic domain and its C-terminal regulatory region are bridged by a leucine zipper, which plays an important role in the activation of Nek2's catalytic activity. Unusual conformational dynamics on the intermediary/slow timescale has thwarted all attempts so far to determine the structure of the Nek2 leucine zipper by means of X-ray crystallography and Nuclear Magnetic Resonance (NMR). Disulfide engineering, the strategic placement of non-native disulfide bonds into flexible regions flanking the coiled coil, was used to modulate the conformational exchange dynamics of this important dimerization domain. The resulting reduction in exchange rate leads to substantial improvements of important features in NMR spectra, such as line width, coherence transfer leakage and relaxation. These effects were comprehensively analyzed for the wild type protein, two single disulfide bond-bearing mutants and another double disulfide bonds-carrying mutant. Furthermore, exchange kinetics were measured across a wide temperature range, allowing for a detailed analysis of activation energy (ΔG‡) and maximal rate constant (k'ex). For one mutant carrying a disulfide bond at its C-terminus, a full backbone NMR assignment could be obtained for both conformers, demonstrating the benefits of the disulfide engineering. Our study demonstrates the first successful application of 'kinetic' disulfide bonds for the purpose of controlling the adverse effects of protein dynamics. Firstly, this provides a promising, robust platform for the full structural and functional investigation of the Nek2 leucine zipper in the future. Secondly, this work broadens the toolbox of protein engineering by disulfide bonds through the addition of a kinetic option in addition to the well-established thermodynamic uses of disulfide bonds.
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12
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Stegmann M, Barclay AN, Metcalfe C. Reduction of leucocyte cell surface disulfide bonds during immune activation is dynamic as revealed by a quantitative proteomics workflow (SH-IQ). Open Biol 2018; 8:rsob.180079. [PMID: 30232098 PMCID: PMC6170505 DOI: 10.1098/rsob.180079] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2018] [Accepted: 08/17/2018] [Indexed: 11/16/2022] Open
Abstract
Communication through cell surface receptors is crucial for maintaining immune homeostasis, coordinating the immune response and pathogen clearance. This is dependent on the interaction of cell surface receptors with their ligands and requires functionally active conformational states. Thus, immune cell function can be controlled by modulating the structure of either the receptor or the ligand. Reductive cleavage of labile disulfide bonds can mediate such an allosteric change, resulting in modulation of the immune system by a hitherto little studied mechanism. Identifying proteins with labile disulfide bonds and determining the extent of reduction is crucial in elucidating the functional result of reduction. We describe a mass spectrometry-based method—thiol identification and quantitation (SH-IQ)—to identify, quantify and monitor such reduction of labile disulfide bonds in primary cells during immune activation. These results provide the first insight into the extent and dynamics of labile disulfide bond reduction in leucocyte cell surface proteins upon immune activation. We show that this process is thiol oxidoreductase-dependent and mainly affects activatory (e.g. CD132, SLAMF1) and adhesion (CD44, ICAM1) molecules, suggesting a mechanism to prevent over-activation of the immune system and excessive accumulation of leucocytes at sites of inflammation.
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Affiliation(s)
- Monika Stegmann
- The Sir William Dunn School of Pathology, University of Oxford, Oxford, UK
| | - A Neil Barclay
- The Sir William Dunn School of Pathology, University of Oxford, Oxford, UK
| | - Clive Metcalfe
- The Sir William Dunn School of Pathology, University of Oxford, Oxford, UK .,National Institute of Biological Standards and Control, Blanche Lane, South Mimms, UK
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14
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Lakbub JC, Shipman JT, Desaire H. Recent mass spectrometry-based techniques and considerations for disulfide bond characterization in proteins. Anal Bioanal Chem 2017; 410:2467-2484. [PMID: 29256076 DOI: 10.1007/s00216-017-0772-1] [Citation(s) in RCA: 51] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2017] [Revised: 11/09/2017] [Accepted: 11/17/2017] [Indexed: 12/21/2022]
Abstract
Disulfide bonds are important structural moieties of proteins: they ensure proper folding, provide stability, and ensure proper function. With the increasing use of proteins for biotherapeutics, particularly monoclonal antibodies, which are highly disulfide bonded, it is now important to confirm the correct disulfide bond connectivity and to verify the presence, or absence, of disulfide bond variants in the protein therapeutics. These studies help to ensure safety and efficacy. Hence, disulfide bonds are among the critical quality attributes of proteins that have to be monitored closely during the development of biotherapeutics. However, disulfide bond analysis is challenging because of the complexity of the biomolecules. Mass spectrometry (MS) has been the go-to analytical tool for the characterization of such complex biomolecules, and several methods have been reported to meet the challenging task of mapping disulfide bonds in proteins. In this review, we describe the relevant, recent MS-based techniques and provide important considerations needed for efficient disulfide bond analysis in proteins. The review focuses on methods for proper sample preparation, fragmentation techniques for disulfide bond analysis, recent disulfide bond mapping methods based on the fragmentation techniques, and automated algorithms designed for rapid analysis of disulfide bonds from liquid chromatography-MS/MS data. Researchers involved in method development for protein characterization can use the information herein to facilitate development of new MS-based methods for protein disulfide bond analysis. In addition, individuals characterizing biotherapeutics, especially by disulfide bond mapping in antibodies, can use this review to choose the best strategies for disulfide bond assignment of their biologic products. Graphical Abstract This review, describing characterization methods for disulfide bonds in proteins, focuses on three critical components: sample preparation, mass spectrometry data, and software tools.
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Affiliation(s)
- Jude C Lakbub
- Ralph N. Adams Institute for Bioanalytical Chemistry, Department of Chemistry, University of Kansas, 1251 Wescoe Hall Dr, Lawrence, KS, 66045, USA
| | - Joshua T Shipman
- Ralph N. Adams Institute for Bioanalytical Chemistry, Department of Chemistry, University of Kansas, 1251 Wescoe Hall Dr, Lawrence, KS, 66045, USA
| | - Heather Desaire
- Ralph N. Adams Institute for Bioanalytical Chemistry, Department of Chemistry, University of Kansas, 1251 Wescoe Hall Dr, Lawrence, KS, 66045, USA.
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15
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Bechtel TJ, Weerapana E. From structure to redox: The diverse functional roles of disulfides and implications in disease. Proteomics 2017; 17. [PMID: 28044432 DOI: 10.1002/pmic.201600391] [Citation(s) in RCA: 92] [Impact Index Per Article: 13.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2016] [Revised: 12/02/2016] [Accepted: 12/28/2016] [Indexed: 12/16/2022]
Abstract
This review provides a comprehensive overview of the functional roles of disulfide bonds and their relevance to human disease. The critical roles of disulfide bonds in protein structure stabilization and redox regulation of protein activity are addressed. Disulfide bonds are essential to the structural stability of many proteins within the secretory pathway and can exist as intramolecular or inter-domain disulfides. The proper formation of these bonds often relies on folding chaperones and oxidases such as members of the protein disulfide isomerase (PDI) family. Many of the PDI family members catalyze disulfide-bond formation, reduction, and isomerization through redox-active disulfides and perturbed PDI activity is characteristic of carcinomas and neurodegenerative diseases. In addition to catalytic function in oxidoreductases, redox-active disulfides are also found on a diverse array of cellular proteins and act to regulate protein activity and localization in response to oxidative changes in the local environment. These redox-active disulfides are either dynamic intramolecular protein disulfides or mixed disulfides with small-molecule thiols generating glutathionylation and cysteinylation adducts. The oxidation and reduction of redox-active disulfides are mediated by cellular reactive oxygen species and activity of reductases, such as glutaredoxin and thioredoxin. Dysregulation of cellular redox conditions and resulting changes in mixed disulfide formation are directly linked to diseases such as cardiovascular disease and Parkinson's disease.
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Affiliation(s)
- Tyler J Bechtel
- Department of Chemistry, Boston College, Chestnut Hill, MA, USA
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16
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Plugis NM, Palanski BA, Weng CH, Albertelli M, Khosla C. Thioredoxin-1 Selectively Activates Transglutaminase 2 in the Extracellular Matrix of the Small Intestine: IMPLICATIONS FOR CELIAC DISEASE. J Biol Chem 2016; 292:2000-2008. [PMID: 28003361 DOI: 10.1074/jbc.m116.767988] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2016] [Revised: 12/13/2016] [Indexed: 11/06/2022] Open
Abstract
Transglutaminase 2 (TG2) catalyzes transamidation or deamidation of its substrates and is ordinarily maintained in a catalytically inactive state in the intestine and other organs. Aberrant TG2 activity is thought to play a role in celiac disease, suggesting that a better understanding of TG2 regulation could help to elucidate the mechanistic basis of this malady. Structural and biochemical analysis has led to the hypothesis that extracellular TG2 activation involves reduction of an allosteric disulfide bond by thioredoxin-1 (TRX), but cellular and in vivo evidence for this proposal is lacking. To test the physiological relevance of this hypothesis, we first showed that macrophages exposed to pro-inflammatory stimuli released TRX in sufficient quantities to activate their extracellular pools of TG2. By using the C35S mutant of TRX, which formed a metastable mixed disulfide bond with TG2, we demonstrated that these proteins specifically recognized each other in the extracellular matrix of fibroblasts. When injected into mice and visualized with antibodies, we observed the C35S TRX mutant bound to endogenous TG2 as its principal protein partner in the small intestine. Control experiments showed no labeling of TG2 knock-out mice. Intravenous administration of recombinant TRX in wild-type mice, but not TG2 knock-out mice, led to a rapid rise in intestinal transglutaminase activity in a manner that could be inhibited by small molecules targeting TG2 or TRX. Our findings support the potential pathophysiological relevance of TRX in celiac disease and establish the Cys370-Cys371 disulfide bond of TG2 as one of clearest examples of an allosteric disulfide bond in mammals.
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Affiliation(s)
- Nicholas M Plugis
- From the Department of Chemistry, Stanford University, Stanford, California 94305
| | - Brad A Palanski
- From the Department of Chemistry, Stanford University, Stanford, California 94305
| | - Chih-Hisang Weng
- From the Department of Chemistry, Stanford University, Stanford, California 94305; the School of Medicine, Stanford University, Stanford, California 94305; the Medical Science Training Program, Stanford University, Stanford, California 94305
| | - Megan Albertelli
- Department of Comparative Medicine, Stanford University, Stanford, California 94305
| | - Chaitan Khosla
- From the Department of Chemistry, Stanford University, Stanford, California 94305; Department of Chemical Engineering, Stanford University, Stanford, California 94305; Stanford ChEM-H, Stanford University, Stanford, California 94305.
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17
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Karimi M, Ignasiak MT, Chan B, Croft AK, Radom L, Schiesser CH, Pattison DI, Davies MJ. Reactivity of disulfide bonds is markedly affected by structure and environment: implications for protein modification and stability. Sci Rep 2016; 6:38572. [PMID: 27941824 PMCID: PMC5150571 DOI: 10.1038/srep38572] [Citation(s) in RCA: 80] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2016] [Accepted: 11/09/2016] [Indexed: 11/09/2022] Open
Abstract
Disulfide bonds play a key role in stabilizing protein structures, with disruption strongly associated with loss of protein function and activity. Previous data have suggested that disulfides show only modest reactivity with oxidants. In the current study, we report kinetic data indicating that selected disulfides react extremely rapidly, with a variation of 104 in rate constants. Five-membered ring disulfides are particularly reactive compared with acyclic (linear) disulfides or six-membered rings. Particular disulfides in proteins also show enhanced reactivity. This variation occurs with multiple oxidants and is shown to arise from favorable electrostatic stabilization of the incipient positive charge on the sulfur reaction center by remote groups, or by the neighboring sulfur for conformations in which the orbitals are suitably aligned. Controlling these factors should allow the design of efficient scavengers and high-stability proteins. These data are consistent with selective oxidative damage to particular disulfides, including those in some proteins.
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Affiliation(s)
- Maryam Karimi
- The Heart Research Institute, 7 Eliza St, Newtown, NSW, 2042, Australia.,Faculty of Medicine, University of Sydney, NSW, 2006, Australia
| | - Marta T Ignasiak
- Department of Biomedical Science, Panum Institute, University of Copenhagen, Blegdamsvej 3, Copenhagen 2200, Denmark
| | - Bun Chan
- School of Chemistry, University of Sydney, Sydney, NSW 2006, Australia
| | - Anna K Croft
- Department of Chemical and Environmental Engineering, University of Nottingham, Nottingham NG7 2RD, Great Britain
| | - Leo Radom
- School of Chemistry, University of Sydney, Sydney, NSW 2006, Australia
| | - Carl H Schiesser
- School of Chemistry, Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Victoria 3010, Australia
| | - David I Pattison
- The Heart Research Institute, 7 Eliza St, Newtown, NSW, 2042, Australia.,Faculty of Medicine, University of Sydney, NSW, 2006, Australia
| | - Michael J Davies
- The Heart Research Institute, 7 Eliza St, Newtown, NSW, 2042, Australia.,Faculty of Medicine, University of Sydney, NSW, 2006, Australia.,Department of Biomedical Science, Panum Institute, University of Copenhagen, Blegdamsvej 3, Copenhagen 2200, Denmark
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18
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Redox Status of β2GPI in Different Stages of Diabetic Angiopathy. DISEASE MARKERS 2016; 2016:8246839. [PMID: 27818568 PMCID: PMC5081428 DOI: 10.1155/2016/8246839] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/16/2016] [Accepted: 08/09/2016] [Indexed: 12/16/2022]
Abstract
We explored the redox status of beta 2 glycoprotein I (β2GPI) in different stages of diabetic angiopathy. Type 2 diabetes mellitus (T2DM) had a significantly lower proportion of reduced β2GPI as compared to healthy controls (p < 0.05). There was a trend that the mild coronal atherosclerosis heart disease (CAD) had higher proportion of reduced β2GPI than non-CAD and severe-CAD groups, however without significances (p > 0.05). The mild-A-stenosis group and mild-diabetic retinopathy (DR) groups had higher proportion of reduced β2GPI than their severely affected counterparts. The mild-slow nerve conduction velocity (NCVS) group had higher proportion of reduced β2GPI than normal nerve conduction velocity (NCVN group) and severe-NCVS groups. The proportion of reduced β2GPI was in positive correlation with 24 h urine microalbumin and total urine protein, and the proportion of reduced β2GPI was in negative correlation with serum and skin advanced glycation end products (AGEs). Taken together, our data implicate that the proportion of reduced β2GPI increased in the early stage of angiopathy and decreased with the aggravation of angiopathy.
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19
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Metcalfe C, Ramasubramoni A, Pula G, Harper MT, Mundell SJ, Coxon CH. Thioredoxin Inhibitors Attenuate Platelet Function and Thrombus Formation. PLoS One 2016; 11:e0163006. [PMID: 27716777 PMCID: PMC5055343 DOI: 10.1371/journal.pone.0163006] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2016] [Accepted: 08/31/2016] [Indexed: 12/14/2022] Open
Abstract
Thioredoxin (Trx) is an oxidoreductase with important physiological function. Imbalances in the NADPH/thioredoxin reductase/thioredoxin system are associated with a number of pathologies, particularly cancer, and a number of clinical trials for thioredoxin and thioredoxin reductase inhibitors have been carried out or are underway. Due to the emerging role and importance of oxidoreductases for haemostasis and the current interest in developing inhibitors for clinical use, we thought it pertinent to assess whether inhibition of the NADPH/thioredoxin reductase/thioredoxin system affects platelet function and thrombosis. We used small molecule inhibitors of Trx (PMX 464 and PX-12) to determine whether Trx activity influences platelet function, as well as an unbiased proteomics approach to identify potential Trx substrates on the surface of platelets that might contribute to platelet reactivity and function. Using LC-MS/MS we found that PMX 464 and PX-12 affected the oxidation state of thiols in a number of cell surface proteins. Key surface receptors for platelet adhesion and activation were affected, including the collagen receptor GPVI and the von Willebrand factor receptor, GPIb. To experimentally validate these findings we assessed platelet function in the presence of PMX 464, PX-12, and rutin (a selective inhibitor of the related protein disulphide isomerase). In agreement with the proteomics data, small molecule inhibitors of thioredoxin selectively inhibited GPVI-mediated platelet activation, and attenuated ristocetin-induced GPIb-vWF-mediated platelet agglutination, thus validating the findings of the proteomics study. These data reveal a novel role for thioredoxin in regulating platelet reactivity via proteins required for early platelet responses at sites of vessel injury (GPVI and GPIb). This work also highlights a potential opportunity for repurposing of PMX 464 and PX-12 as antiplatelet agents.
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Affiliation(s)
- Clive Metcalfe
- Oxford Molecular and Pathology Institute, South Parks Road, Oxford, OX1 3RE, United Kingdom
| | - Anjana Ramasubramoni
- Oxford Molecular and Pathology Institute, South Parks Road, Oxford, OX1 3RE, United Kingdom
| | - Giordano Pula
- Department of Pharmacy and Pharmacology, University of Bath, Claverton Down, Bath, BA2 7AY, United Kingdom
| | - Matthew T. Harper
- Department of Pharmacology, University of Cambridge, Tennis Court Road, Cambridge, CB2 1PD, United Kingdom
| | - Stuart J. Mundell
- Department of Physiology, Pharmacology and Neuroscience, Medical Sciences Building, University of Bristol, University Walk, Bristol, BS8 1TD, United Kingdom
- * E-mail:
| | - Carmen H. Coxon
- Department of Physiology, Pharmacology and Neuroscience, Medical Sciences Building, University of Bristol, University Walk, Bristol, BS8 1TD, United Kingdom
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20
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Abstract
Disulfide bonds represent versatile posttranslational modifications whose roles encompass the structure, catalysis, and regulation of protein function. Due to the oxidizing nature of the extracellular environment, disulfide bonds found in secreted proteins were once believed to be inert. This notion has been challenged by the discovery of redox-sensitive disulfides that, once cleaved, can lead to changes in protein activity. These functional disulfides are twisted into unique configurations, leading to high strain and potential energy. In some cases, cleavage of these disulfides can lead to a gain of function in protein activity. Thus, these motifs can be referred to as switches. We describe the couples that control redox in the extracellular environment, examine several examples of proteins with switchable disulfides, and discuss the potential applications of disulfides in molecular biology.
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Affiliation(s)
- Michael C Yi
- Department of Chemical Engineering, Stanford University, Stanford, California 94305; ,
| | - Chaitan Khosla
- Department of Chemical Engineering, Stanford University, Stanford, California 94305; , .,Department of Chemistry, Stanford University, Stanford, California 94305
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21
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Dávila Costa JS, Leichert L, Alvarez HM, Herrero OM. Label-free and redox proteomic analyses of the triacylglycerol-accumulating Rhodococcus jostii RHA1. Microbiology (Reading) 2015; 161:593-610. [DOI: 10.1099/mic.0.000028] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
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22
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Couvertier SM, Zhou Y, Weerapana E. Chemical-proteomic strategies to investigate cysteine posttranslational modifications. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2014; 1844:2315-30. [PMID: 25291386 DOI: 10.1016/j.bbapap.2014.09.024] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/30/2014] [Revised: 09/08/2014] [Accepted: 09/29/2014] [Indexed: 01/10/2023]
Abstract
The unique combination of nucleophilicity and redox-sensitivity that is characteristic of cysteine residues results in a variety of posttranslational modifications (PTMs), including oxidation, nitrosation, glutathionylation, prenylation, palmitoylation and Michael adducts with lipid-derived electrophiles (LDEs). These PTMs regulate the activity of diverse protein families by modulating the reactivity of cysteine nucleophiles within active sites of enzymes, and governing protein localization between soluble and membrane-bound forms. Many of these modifications are highly labile, sensitive to small changes in the environment, and dynamic, rendering it difficult to detect these modified species within a complex proteome. Several chemical-proteomic platforms have evolved to study these modifications and enable a better understanding of the diversity of proteins that are regulated by cysteine PTMs. These platforms include: (1) chemical probes to selectively tag PTM-modified cysteines; (2) differential labeling platforms that selectively reveal and tag PTM-modified cysteines; (3) lipid, isoprene and LDE derivatives containing bioorthogonal handles; and (4) cysteine-reactivity profiling to identify PTM-induced decreases in cysteine nucleophilicity. Here, we will provide an overview of these existing chemical-proteomic strategies and their effectiveness at identifying PTM-modified cysteine residues within native biological systems.
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Affiliation(s)
| | - Yani Zhou
- Boston College, Chestnut Hill, MA 02467, USA
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23
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Northfield SE, Wang CK, Schroeder CI, Durek T, Kan MW, Swedberg JE, Craik DJ. Disulfide-rich macrocyclic peptides as templates in drug design. Eur J Med Chem 2014; 77:248-57. [DOI: 10.1016/j.ejmech.2014.03.011] [Citation(s) in RCA: 84] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2014] [Revised: 02/25/2014] [Accepted: 03/05/2014] [Indexed: 01/04/2023]
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24
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Malojčić G, Owen RL, Glockshuber R. Structural and Mechanistic Insights into the PAPS-Independent Sulfotransfer Catalyzed by Bacterial Aryl Sulfotransferase and the Role of the DsbL/DsbI System in Its Folding. Biochemistry 2014; 53:1870-7. [DOI: 10.1021/bi401725j] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Goran Malojčić
- Institute
of Molecular Biology and Biophysics, ETH Zurich, CH-8093 Zurich, Switzerland
| | - Robin L. Owen
- Diamond
Light Source, Harwell Science and Innovation Campus, Didcot, Oxfordshire OX11 0DE, U.K
| | - Rudi Glockshuber
- Institute
of Molecular Biology and Biophysics, ETH Zurich, CH-8093 Zurich, Switzerland
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25
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Muchowicz A, Firczuk M, Chlebowska J, Nowis D, Stachura J, Barankiewicz J, Trzeciecka A, Kłossowski S, Ostaszewski R, Zagożdżon R, Pu JX, Sun HD, Golab J. Adenanthin targets proteins involved in the regulation of disulphide bonds. Biochem Pharmacol 2014; 89:210-6. [PMID: 24630929 DOI: 10.1016/j.bcp.2014.02.022] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2013] [Revised: 02/26/2014] [Accepted: 02/27/2014] [Indexed: 11/30/2022]
Abstract
Adenanthin has been recently shown to inhibit the enzymatic activities of peroxiredoxins (Prdx) I and II through its functional α,β-unsaturated ketone group serving as a Michael acceptor. A similar group is found in SK053, a compound recently developed by our group to target the thioredoxin-thioredoxin reductase (Trx-TrxR) system. This work provides evidence that next to Prdx I and II adenanthin targets additional proteins including thioredoxin-thioredoxin reductase system as well as protein disulfide isomerase (PDI) that contain a characteristic structural motif, referred to as a thioredoxin fold. Adenanthin inhibits the activity of Trx-TR system and PDI in vitro in the insulin reduction assay and decreases the activity of Trx in cultured cells. Moreover, we identified Trx-1 as an adenanthin binding protein in cells incubated with biotinylated adenanthin as an affinity probe. The results of our studies indicate that adenanthin is a mechanism-selective, rather than an enzyme-specific inhibitor of enzymes containing readily accessible, nucleophilic cysteines. This observation might be of importance in considering potential therapeutic applications of adenanthin to include a range of diseases, where aberrant activity of Prdx, Trx-TrxR and PDI is involved in their pathogenesis.
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Affiliation(s)
- Angelika Muchowicz
- Department of Immunology, Center of Biostructure Research, Medical University of Warsaw, Banacha 1A, 02-097 Warsaw, Poland
| | - Małgorzata Firczuk
- Department of Immunology, Center of Biostructure Research, Medical University of Warsaw, Banacha 1A, 02-097 Warsaw, Poland
| | - Justyna Chlebowska
- Department of Immunology, Center of Biostructure Research, Medical University of Warsaw, Banacha 1A, 02-097 Warsaw, Poland
| | - Dominika Nowis
- Department of Immunology, Center of Biostructure Research, Medical University of Warsaw, Banacha 1A, 02-097 Warsaw, Poland; Genomic Medicine, Department of General, Transplant and Liver Surgery, Medical University of Warsaw, Banacha 1A, 02-097 Warsaw, Poland
| | - Joanna Stachura
- Department of Immunology, Center of Biostructure Research, Medical University of Warsaw, Banacha 1A, 02-097 Warsaw, Poland
| | - Joanna Barankiewicz
- Department of Immunology, Center of Biostructure Research, Medical University of Warsaw, Banacha 1A, 02-097 Warsaw, Poland
| | - Anna Trzeciecka
- Department of Immunology, Center of Biostructure Research, Medical University of Warsaw, Banacha 1A, 02-097 Warsaw, Poland
| | - Szymon Kłossowski
- Institute of Organic Chemistry, Polish Academy of Sciences, Kasprzaka 44/52, 01-224 Warsaw, Poland
| | - Ryszard Ostaszewski
- Institute of Organic Chemistry, Polish Academy of Sciences, Kasprzaka 44/52, 01-224 Warsaw, Poland
| | - Radosław Zagożdżon
- Department of Immunology, Center of Biostructure Research, Medical University of Warsaw, Banacha 1A, 02-097 Warsaw, Poland
| | - Jian-Xin Pu
- Kunming Institute of Botany, Chinese Academy of Science, Kunming, China
| | - Han-Dong Sun
- Kunming Institute of Botany, Chinese Academy of Science, Kunming, China.
| | - Jakub Golab
- Department of Immunology, Center of Biostructure Research, Medical University of Warsaw, Banacha 1A, 02-097 Warsaw, Poland; Institute of Physical Chemistry, Polish Academy of Sciences, Department 3, Warsaw, Poland.
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26
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de Araujo AD, Herzig V, Windley MJ, Dziemborowicz S, Mobli M, Nicholson GM, Alewood PF, King GF. Do vicinal disulfide bridges mediate functionally important redox transformations in proteins? Antioxid Redox Signal 2013; 19:1976-80. [PMID: 23646911 PMCID: PMC3852340 DOI: 10.1089/ars.2013.5365] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Vicinal disulfide bridges, in which a disulfide bond is formed between adjacent cysteine residues, constitute an unusual but expanding class of potential allosteric disulfides. Although vicinal disulfide rings (VDRs) are relatively uncommon, they have proven to be functionally critical in almost all proteins in which they have been discovered. However, it has proved difficult to test whether these sterically constrained disulfides participate in functionally important redox transformations. We demonstrate that chemical replacement of VDRs with dicarba or diselenide bridges can be used to assess whether VDRs function as allosteric disulfides. Our approach leads to the hypothesis that not all VDRs participate in functionally important redox reactions.
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Affiliation(s)
- Aline Dantas de Araujo
- 1 Institute for Molecular Bioscience, The University of Queensland , St. Lucia, Australia
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27
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Abstract
Protein action in nature is generally controlled by the amount of protein produced and by chemical modification of the protein, and both are often perturbed in cancer. The amino acid side chains and the peptide and disulphide bonds that bind the polypeptide backbone can be post-translationally modified. Post-translational cleavage or the formation of disulphide bonds are now being identified in cancer-related proteins and it is timely to consider how these allosteric bonds could be targeted for new therapies.
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Affiliation(s)
- Philip J Hogg
- Lowy Cancer Research Centre and Prince of Wales Clinical School, University of New South Wales, Sydney NSW 2052, Australia.
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28
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Abstract
Protein action in nature is largely controlled by the level of expression and by post-translational modifications. Post-translational modifications result in a proteome that is at least two orders of magnitude more diverse than the genome. There are three basic types of post-translational modifications: covalent modification of an amino acid side chain, hydrolytic cleavage or isomerization of a peptide bond, and reductive cleavage of a disulfide bond. This review addresses the modification of disulfide bonds. Protein disulfide bonds perform either a structural or a functional role, and there are two types of functional disulfide: the catalytic and allosteric bonds. The allosteric disulfide bonds control the function of the mature protein in which they reside by triggering a change when they are cleaved. The change can be in ligand binding, substrate hydrolysis, proteolysis, or oligomer formation. The allosteric disulfides are cleaved by oxidoreductases or by thiol/disulfide exchange, and the configurations of the disulfides and the secondary structures that they link share some recurring features. How these bonds are being identified using bioinformatics and experimental screens and what the future holds for this field of research are also discussed.
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Affiliation(s)
- Kristina M Cook
- Lowy Cancer Research Centre and Prince of Wales Clinical School, University of New South Wales, Sydney NSW2052, Australia
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29
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Conibear AC, Rosengren KJ, Daly NL, Henriques ST, Craik DJ. The cyclic cystine ladder in θ-defensins is important for structure and stability, but not antibacterial activity. J Biol Chem 2013; 288:10830-40. [PMID: 23430740 DOI: 10.1074/jbc.m113.451047] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
θ-Defensins are ribosomally synthesized cyclic peptides found in the leukocytes of some primate species and have promising applications as antimicrobial agents and scaffolds for peptide drugs. The cyclic cystine ladder motif, comprising a cyclic peptide backbone and three parallel disulfide bonds, is characteristic of θ-defensins. In this study, we explore the role of the cyclic peptide backbone and cystine ladder in the structure, stability, and activity of θ-defensins. θ-Defensin analogues with different numbers and combinations of disulfide bonds were synthesized and characterized in terms of their NMR solution structures, serum and thermal stabilities, and their antibacterial and membrane-binding activities. Whereas the structures and stabilities of the peptides were primarily dependent on the number and position of the disulfide bonds, their antibacterial and membrane-binding properties were dependent on the cyclic backbone. The results provide insights into the mechanism of action of θ-defensins and illustrate the potential of θ-defensin analogues as scaffolds for peptide drug design.
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Affiliation(s)
- Anne C Conibear
- Division of Chemistry and Structural Biology, Institute for Molecular Bioscience, the University of Queensland, Brisbane, Queensland 4072, Australia
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30
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Rapid activation of monocyte tissue factor by antithymocyte globulin is dependent on complement and protein disulfide isomerase. Blood 2013; 121:2324-35. [PMID: 23315166 DOI: 10.1182/blood-2012-10-460493] [Citation(s) in RCA: 88] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Lymphocyte depletion with antithymocyte globulin (ATG) can be complicated by systemic coagulation activation. We found that ATG activated tissue factor procoagulant activity (TF PCA) on monocytic cells more potently than other stimuli that decrypt TF, including cell disruption, TF pathway inhibitor inhibition, and calcium ionophore treatment. Induction of TF PCA by ATG was dependent on lipid raft integrity and complement activation. We showed that ATG-mediated TF activation required complement activation until assembly of the C5b-7 membrane insertion complex, but not lytic pore formation by the membrane attack complex C5b-9. Consistently, induction of TF PCA by ATG did not require maximal phosphatidylserine membrane exposure and was not correlated with the magnitude of complement-induced lytic cell injury. Blockade of free thiols, an inhibitory monoclonal antibody to protein disulfide isomerase (PDI), and the small-molecule PDI antagonist quercetin-3-rutinoside prevented ATG-mediated TF activation, and C5 complement activation resulted in oxidation of cell surface PDI. This rapid and potent mechanism of cellular TF activation represents a novel connection between the complement system and cell surface PDI-mediated thiol-disulfide exchange. Delineation of this clinically relevant mechanism of activation of the extrinsic coagulation pathway during immunosuppressive therapy with ATG may have broader implications for vascular thrombosis associated with inflammatory disorders.
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Conibear AC, Rosengren KJ, Harvey PJ, Craik DJ. Structural characterization of the cyclic cystine ladder motif of θ-defensins. Biochemistry 2012; 51:9718-26. [PMID: 23148585 DOI: 10.1021/bi301363a] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The θ-defensins are, to date, the only known ribosomally synthesized cyclic peptides in mammals, and they have promising antimicrobial bioactivities. The characteristic structural motif of the θ-defensins is the cyclic cystine ladder, comprising a cyclic peptide backbone and three parallel disulfide bonds. In contrast to the cyclic cystine knot, which characterizes the plant cyclotides, the cyclic cystine ladder has not been as well described as a structural motif. Here we report the solution structures and nuclear magnetic resonance relaxation properties in aqueous solution of three representative θ-defensins from different species. Our data suggest that the θ-defensins are more rigid and structurally defined than previously thought. In addition, all three θ-defensins were found to self-associate in aqueous solution in a concentration-dependent and reversible manner, a property that might have a role in their mechanism of action. The structural definition of the θ-defensins and the cyclic cystine ladder will help to guide exploitation of these molecules as structural frameworks for the design of peptide drugs.
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Affiliation(s)
- Anne C Conibear
- Division of Chemistry and Structural Biology, Institute for Molecular Bioscience, The University of Queensland, Brisbane, QLD 4072, Australia
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Giannakopoulos B, Gao L, Qi M, Wong JW, Yu DM, Vlachoyiannopoulos PG, Moutsopoulos HM, Atsumi T, Koike T, Hogg P, Qi JC, Krilis SA. Factor XI is a substrate for oxidoreductases: enhanced activation of reduced FXI and its role in antiphospholipid syndrome thrombosis. J Autoimmun 2012; 39:121-9. [PMID: 22704541 DOI: 10.1016/j.jaut.2012.05.005] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2012] [Accepted: 05/17/2012] [Indexed: 01/06/2023]
Abstract
Factor XI (FXI), a disulfide-linked covalent homodimer, circulates in plasma, and upon activation initiates the intrinsic/consolidation phase of coagulation. We present evidence that disulfide bonds in FXI are reduced to free thiols by oxidoreductases thioredoxin-1 (TRX-1) and protein disulfide isomerase (PDI). We identified that Cys362-Cys482 and Cys118-Cys147 disulfide bonds are reduced by TRX-1. The activation of TRX-1-treated FXI by thrombin, FXIIa or FXIa was significantly increased compared to non-reduced FXI, indicating that the reduced factor is more efficiently activated than the oxidized protein. Using a novel ELISA system, we compared the amount of reduced FXI in antiphospholipid syndrome (APS) thrombosis patients with levels in healthy controls, and found that APS patients have higher levels of reduced FXI. This may have implication for understanding the contribution of FXI to APS thrombosis, and the predisposition to thrombosis in patients with elevated plasma levels of reduced FXI.
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Affiliation(s)
- Bill Giannakopoulos
- Department of Immunology, Allergy and Infectious Diseases, St. George Hospital, University of New South Wales, Sydney, Australia.
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van den Hengel LG, van den Berg YW, Reitsma PH, Bos MHA, Versteeg HH. Evolutionary conservation of the tissue factor disulfide bonds and identification of a possible oxidoreductase binding motif. J Thromb Haemost 2012; 10:161-2. [PMID: 22066736 DOI: 10.1111/j.1538-7836.2011.04556.x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Mirarabshahi P, Abdelatti M, Krilis S. Post-translational oxidative modification of β2-glycoprotein I and its role in the pathophysiology of the antiphospholipid syndrome. Autoimmun Rev 2011; 11:779-80. [PMID: 22240262 DOI: 10.1016/j.autrev.2011.12.007] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2011] [Accepted: 12/17/2011] [Indexed: 11/20/2022]
Abstract
Vascular thrombosis and/or recurrent miscarriages are the main characteristics defining Antiphospholipid Syndrome (APS). Currently there is no well-defined clinical features and/or laboratory tests that predicts the risk of adverse prognostic outcomes in APS. In this short review, we report the importance of posttranslational modification of beta2 glycoprotein I, the major autoantigen in the APS beta2 glycoprotein I that may, in part, explain possible mechanisms for the generation of auto antibodies to beta2 glycoprotein I. A specific ELISA measuring the level of oxidised beta2 glycoprotein I could be used as a potential new laboratory test - along with other laboratory tests - to more accurately predict the risk of having a clinical event in patients with APS.
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Affiliation(s)
- Peyman Mirarabshahi
- Department of Immunology, Allergy and Infectious Diseases, St. George Hospital, University of New South Wales, Sydney, Australia
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Brandes N, Reichmann D, Tienson H, Leichert LI, Jakob U. Using quantitative redox proteomics to dissect the yeast redoxome. J Biol Chem 2011; 286:41893-41903. [PMID: 21976664 DOI: 10.1074/jbc.m111.296236] [Citation(s) in RCA: 90] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
To understand and eventually predict the effects of changing redox conditions and oxidant levels on the physiology of an organism, it is essential to gain knowledge about its redoxome: the proteins whose activities are controlled by the oxidation status of their cysteine thiols. Here, we applied the quantitative redox proteomic method OxICAT to Saccharomyces cerevisiae and determined the in vivo thiol oxidation status of almost 300 different yeast proteins distributed among various cellular compartments. We found that a substantial number of cytosolic and mitochondrial proteins are partially oxidized during exponential growth. Our results suggest that prevailing redox conditions constantly control central cellular pathways by fine-tuning oxidation status and hence activity of these proteins. Treatment with sublethal H(2)O(2) concentrations caused a subset of 41 proteins to undergo substantial thiol modifications, thereby affecting a variety of different cellular pathways, many of which are directly or indirectly involved in increasing oxidative stress resistance. Classification of the identified protein thiols according to their steady-state oxidation levels and sensitivity to peroxide treatment revealed that redox sensitivity of protein thiols does not predict peroxide sensitivity. Our studies provide experimental evidence that the ability of protein thiols to react to changing peroxide levels is likely governed by both thermodynamic and kinetic parameters, making predicting thiol modifications challenging and de novo identification of peroxide sensitive protein thiols indispensable.
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Affiliation(s)
- Nicolas Brandes
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, Michigan 48109
| | - Dana Reichmann
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, Michigan 48109
| | - Heather Tienson
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, Michigan 48109
| | - Lars I Leichert
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, Michigan 48109
| | - Ursula Jakob
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, Michigan 48109.
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Jin X, Stamnaes J, Klöck C, DiRaimondo TR, Sollid LM, Khosla C. Activation of extracellular transglutaminase 2 by thioredoxin. J Biol Chem 2011; 286:37866-73. [PMID: 21908620 DOI: 10.1074/jbc.m111.287490] [Citation(s) in RCA: 87] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
The mechanism of activation of transglutaminase 2 (TG2) in the extracellular matrix remains a fundamental mystery in our understanding of the biology of this multifunctional mammalian enzyme. Earlier investigations have highlighted the role of a disulfide bond formed by vicinal Cys residues in maintaining calcium-bound TG2 in an inactive state. Here, we have shown that the redox potential of this disulfide bond is approximately -190 mV, a high value for a disulfide bond in proteins. Consistent with this observation, TG2 activity in a freshly wounded fibroblast culture depends upon the redox potential of the environment. We sought to identify a physiological mechanism for the activation of oxidized TG2. With a k(cat)/K(m) of 1.6 μm(-1) min(-1), human thioredoxin (Trx) was a highly specific activator of oxidized human TG2. Trx-mediated activation of TG2 was blocked by PX-12, a small molecule Trx inhibitor that is undergoing clinical trials as a cancer chemotherapeutic agent. In a mixed culture containing fibroblasts and monocytic cells, interferon-γ stimulated Trx release from monocytes, which in turn activated TG2 around the fibroblasts. Recombinant human Trx could also activate extracellular TG2 in cryosections of human and mouse small intestinal biopsies. In addition to explaining how TG2 can be activated by dietary gluten in the small intestinal mucosa of celiac sprue patients, our findings reveal a new strategy for inhibiting the undesirable consequences of TG2 activity in this widespread, lifelong disease.
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Affiliation(s)
- Xi Jin
- Department of Chemistry, Stanford University, Stanford, California 94305, USA
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Schiedel AC, Hinz S, Thimm D, Sherbiny F, Borrmann T, Maass A, Müller CE. The four cysteine residues in the second extracellular loop of the human adenosine A2B receptor: role in ligand binding and receptor function. Biochem Pharmacol 2011; 82:389-99. [PMID: 21620804 DOI: 10.1016/j.bcp.2011.05.008] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2011] [Revised: 05/09/2011] [Accepted: 05/11/2011] [Indexed: 11/17/2022]
Abstract
The adenosine A(2B) receptor is of considerable interest as a new drug target for the treatment of asthma, inflammatory diseases, pain, and cancer. In the present study we investigated the role of the cysteine residues in the extracellular loop 2 (ECL2) of the receptor, which is particularly cysteine-rich, by a combination of mutagenesis, molecular modeling, chemical and pharmacological experiments. Pretreatment of CHO cells recombinantly expressing the human A(2B) receptor with dithiothreitol led to a 74-fold increase in the EC(50) value of the agonist NECA in cyclic AMP accumulation. In the C78(3.25)S and the C171(45.50)S mutant high-affinity binding of the A(2B) antagonist radioligand [(3)H]PSB-603 was abolished and agonists were virtually inactive in cAMP assays. This indicates that the C3.25-C45.50 disulfide bond, which is highly conserved in GPCRs, is also important for binding and function of A(2B) receptors. In contrast, the C166(45.45)S and the C167(45.46)S mutant as well as the C166(45.45)S-C167(45.46)S double mutant behaved like the wild-type receptor, while in the C154(45.33)S mutant significant, although more subtle effects on cAMP accumulation were observed - decrease (BAY60-6583) or increase (NECA) - depending on the structure of the investigated agonist. In contrast to the X-ray structure of the closely related A(2A) receptor, which showed four disulfide bonds, the present data indicate that in the A(2B) receptor only the C3.25-C45.50 disulfide bond is essential for ligand binding and receptor activation. Thus, the cysteine residues in the ECL2 of the A(2B) receptor not involved in stabilization of the receptor structure may have other functions.
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Affiliation(s)
- Anke C Schiedel
- PharmaCenter Bonn, Pharmaceutical Institute, Pharmaceutical Chemistry I, University of Bonn, An der Immenburg 4, D-53121 Bonn, Germany.
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Abstract
The articles in this forum issue describe various aspects of the folding of disulfide-rich proteins. They include review articles using proteins such as bovine pancreatic trypsin inhibitor as models to highlight the range of folding pathways seen in disulfide-rich proteins, along with a detailed analysis of the methods used to study them. Following two comprehensive reviews on the methods and applications of protein folding, three original articles in this issue focus on two specific classes of disulfide-rich proteins that have applications in drug design and development, namely cyclotides and conotoxins. Cyclotides are head-to-tail cyclic and disulfide-rich proteins from plants and function as a defense against insect attack. Conotoxins are the disulfide-rich components of the venom of marine cone snails that is used to capture prey. These research articles report on factors that modulate protein folding pathways in these molecules and determine the outcomes of protein folding, that is, yield and heterogeneity of products. Finally, the issue concludes with a comprehensive review on a different type of disulfide bond, namely those that have a functional rather than structural role in proteins, with a particular focus on allosteric disulfide bonds that modify protein function.
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Affiliation(s)
- David J Craik
- Division of Chemistry and Structural Biology, Institute for Molecular Bioscience, The University of Queensland, Brisbane, Australia.
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