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Harris RC, Liu R, Shen J. Predicting Reactive Cysteines with Implicit-Solvent-Based Continuous Constant pH Molecular Dynamics in Amber. J Chem Theory Comput 2020; 16:3689-3698. [PMID: 32330035 PMCID: PMC7772776 DOI: 10.1021/acs.jctc.0c00258] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Cysteines existing in the deprotonated thiolate form or having a tendency to become deprotonated are important players in enzymatic and cellular redox functions and frequently exploited in covalent drug design; however, most computational studies assume cysteines as protonated. Thus, developing an efficient tool that can make accurate and reliable predictions of cysteine protonation states is timely needed. We recently implemented a generalized Born (GB) based continuous constant pH molecular dynamics (CpHMD) method in Amber for protein pKa calculations on CPUs and GPUs. Here we benchmark the performance of GB-CpHMD for predictions of cysteine pKa's and reactivities using a data set of 24 proteins with both down- and upshifted cysteine pKa's. We found that 10 ns single-pH or 4 ns replica-exchange CpHMD titrations gave root-mean-square errors of 1.2-1.3 and correlation coefficients of 0.8-0.9 with respect to experiment. The accuracy of predicting thiolates or reactive cysteines at physiological pH with single-pH titrations is 86 or 81% with a precision of 100 or 90%, respectively. This performance well surpasses the traditional structure-based methods, particularly a widely used empirical pKa tool that gives an accuracy less than 50%. We discuss simulation convergence, dependence on starting structures, common determinants of the pKa downshifts and upshifts, and the origin of the discrepancies from the structure-based calculations. Our work suggests that CpHMD titrations can be performed on a desktop computer equipped with a single GPU card to predict cysteine protonation states for a variety of applications, from understanding biological functions to covalent drug design.
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Affiliation(s)
- Robert C Harris
- Department of Pharmaceutical Sciences, University of Maryland School of Pharmacy, Baltimore, Maryland 21201, United States
| | - Ruibin Liu
- ComputChem LLC, Baltimore, Maryland 21202, United States
| | - Jana Shen
- Department of Pharmaceutical Sciences, University of Maryland School of Pharmacy, Baltimore, Maryland 21201, United States
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Xiang MH, Huang H, Liu XJ, Tong ZX, Zhang CX, Wang F, Yu RQ, Jiang JH. Mitochondrion-Targeting Fluorescence Probe via Reduction Induced Charge Transfer for Fast Methionine Sulfoxide Reductases Imaging. Anal Chem 2019; 91:5489-5493. [DOI: 10.1021/acs.analchem.9b00383] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Affiliation(s)
- Mei-Hao Xiang
- State Key Laboratory of Chemo/Bio-Sensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University, Changsha, Hunan 410082, China
| | - Hui Huang
- State Key Laboratory of Chemo/Bio-Sensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University, Changsha, Hunan 410082, China
| | - Xian-Jun Liu
- State Key Laboratory of Chemo/Bio-Sensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University, Changsha, Hunan 410082, China
| | - Zong-Xuan Tong
- State Key Laboratory of Chemo/Bio-Sensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University, Changsha, Hunan 410082, China
| | - Chun-Xia Zhang
- State Key Laboratory of Chemo/Bio-Sensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University, Changsha, Hunan 410082, China
| | - Fenglin Wang
- State Key Laboratory of Chemo/Bio-Sensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University, Changsha, Hunan 410082, China
| | - Ru-Qin Yu
- State Key Laboratory of Chemo/Bio-Sensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University, Changsha, Hunan 410082, China
| | - Jian-Hui Jiang
- State Key Laboratory of Chemo/Bio-Sensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University, Changsha, Hunan 410082, China
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Liu JS, Cui ZJ. Pancreatic Stellate Cells Serve as a Brake Mechanism on Pancreatic Acinar Cell Calcium Signaling Modulated by Methionine Sulfoxide Reductase Expression. Cells 2019; 8:cells8020109. [PMID: 30717164 PMCID: PMC6406918 DOI: 10.3390/cells8020109] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2019] [Revised: 01/28/2019] [Accepted: 01/29/2019] [Indexed: 02/06/2023] Open
Abstract
Although methionine sulfoxide reductase (Msr) is known to modulate the activity of multiple functional proteins, the roles of Msr in pancreatic stellate cell physiology have not been reported. In the present work we investigated expression and function of Msr in freshly isolated and cultured rat pancreatic stellate cells. Msr expression was determined by RT-PCR, Western blot and immunocytochemistry. Msr over-expression was achieved by transfection with adenovirus vectors. Pancreatic stellate cells were co-cultured with pancreatic acinar cells AR4-2J in monolayer culture. Pancreatic stellate and acinar cell function was monitored by Fura-2 calcium imaging. Rat pancreatic stellate cells were found to express MsrA, B1, B2, their expressions diminished in culture. Over-expressions of MsrA, B1 or B2 were found to enhance ATP-stimulated calcium increase but decreased reactive oxygen species generation and lipopolysaccharide-elicited IL-1 production. Pancreatic stellate cell-co-culture with AR4-2J blunted cholecystokinin- and acetylcholine-stimulated calcium increases in AR4-2J, depending on acinar/stellate cell ratio, this inhibition was reversed by MsrA, B1 over-expression in stellate cells or by Met supplementation in the co-culture medium. These data suggest that Msr play important roles in pancreatic stellate cell function and the stellate cells may serve as a brake mechanism on pancreatic acinar cell calcium signaling modulated by stellate cell Msr expression.
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Affiliation(s)
- Jin Shuai Liu
- Institute of Cell Biology, Beijing Normal University, Beijing 100875, China.
| | - Zong Jie Cui
- Institute of Cell Biology, Beijing Normal University, Beijing 100875, China.
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Lim JM, Lim JC, Kim G, Levine RL. Myristoylated methionine sulfoxide reductase A is a late endosomal protein. J Biol Chem 2018; 293:7355-7366. [PMID: 29593096 DOI: 10.1074/jbc.ra117.000473] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2017] [Revised: 03/19/2018] [Indexed: 12/11/2022] Open
Abstract
Methionine residues in proteins provide antioxidant defense by reacting with oxidizing species, which oxidize methionine to methionine sulfoxide. Reduction of the sulfoxide back to methionine is catalyzed by methionine sulfoxide reductases, essential for protection against oxidative stress. The nonmyristoylated form of methionine sulfoxide reductase A (MSRA) is present in mitochondria, whereas the myristoylated form has been previously reported to be cytosolic. Despite the importance of MSRA in antioxidant defense, its in vivo binding partners and substrates have not been identified. Starting with a protein array, and followed by immunoprecipitation experiments, colocalization studies, and subcellular fractionation, we identified the late endosomal protein, StAR-related lipid transfer domain-containing 3 (STARD3), as a binding partner of myristoylated MSRA, but not of nonmyristoylated MSRA. STARD3 is known to have both membrane-binding and cytosolic domains that are important in STARD3-mediated transport of cholesterol from the endoplasmic reticulum to the endosome. We found that the STARD3 cytosolic domain localizes MSRA to the late endosome. We propose that the previous conclusion that myristoylated MSRA is strictly a cytosolic protein is artifactual and likely due to vigorous overexpression of MSRA. We conclude that myristoylated MSRA is a late endosomal protein that may play a role in lipid metabolism or may protect endosomal proteins from oxidative damage.
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Affiliation(s)
- Jung Mi Lim
- Laboratory of Biochemistry, NHLBI, National Institutes of Health, Bethesda, Maryland 20892
| | - Jung Chae Lim
- Laboratory of Biochemistry, NHLBI, National Institutes of Health, Bethesda, Maryland 20892
| | - Geumsoo Kim
- Laboratory of Biochemistry, NHLBI, National Institutes of Health, Bethesda, Maryland 20892
| | - Rodney L Levine
- Laboratory of Biochemistry, NHLBI, National Institutes of Health, Bethesda, Maryland 20892.
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Dalongeville A, Benestan L, Mouillot D, Lobreaux S, Manel S. Combining six genome scan methods to detect candidate genes to salinity in the Mediterranean striped red mullet (Mullus surmuletus). BMC Genomics 2018; 19:217. [PMID: 29580201 PMCID: PMC5870821 DOI: 10.1186/s12864-018-4579-z] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2017] [Accepted: 03/02/2018] [Indexed: 12/24/2022] Open
Abstract
Background Adaptive genomics may help predicting how a species will respond to future environmental changes. Genomic signatures of local adaptation in marine organisms are often driven by environmental selective agents impacting the physiology of organisms. With one of the highest salinity level, the Mediterranean Sea provides an excellent model to investigate adaptive genomic divergence underlying salinity adaptation. In the present study, we combined six genome scan methods to detect potential genomic signal of selection in the striped red mullet (Mullus surmuletus) populations distributed across a wide salinity gradient. We then blasted these outlier sequences on published fish genomic resources in order to identify relevant potential candidate genes for salinity adaptation in this species. Results Altogether, the six genome scan methods found 173 outliers out of 1153 SNPs. Using a blast approach, we discovered four candidate SNPs belonging to three genes potentially implicated in adaptation of M. surmuletus to salinity. The allele frequency at one of these SNPs significantly increases with salinity independently from the effect of longitude. The gene associated to this SNP, SOCS2, encodes for an inhibitor of cytokine and has previously been shown to be expressed under osmotic pressure in other marine organisms. Additionally, our results showed that genome scan methods not correcting for spatial structure can still be an efficient strategy to detect potential footprints of selection, when the spatial and environmental variation are confounded, and then, correcting for spatial structure in a second step represents a conservative method. Conclusion The present outcomes bring evidences of potential genomic footprint of selection, which suggest an adaptive response of M. surmuletus to salinity conditions in the Mediterranean Sea. Additional genomic data such as sequencing of a full-genome and transcriptome analyses of gene expression would provide new insights regarding the possibility that some striped red mullet populations are locally adapted to their saline environment. Electronic supplementary material The online version of this article (10.1186/s12864-018-4579-z) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Alicia Dalongeville
- CEFE UMR 5175, EPHE, PSL Research University, CNRS, UM, SupAgro, IRD, INRA, 34293, Montpellier, France. .,MARBEC UMR 9190, CNRS - IRD - Université Montpellier - Ifremer, 34095, Montpellier, France.
| | - Laura Benestan
- Departement de Biologie, Institut de Biologie Intégrative et des Systèmes (IBIS), Université Laval, Québec, Canada
| | - David Mouillot
- MARBEC UMR 9190, CNRS - IRD - Université Montpellier - Ifremer, 34095, Montpellier, France
| | - Stephane Lobreaux
- Laboratoire d'Ecologie Alpine, UMR-CNRS 5553, Université Joseph Fourier, BP53 38041, Grenoble, France
| | - Stéphanie Manel
- CEFE UMR 5175, EPHE, PSL Research University, CNRS, UM, SupAgro, IRD, INRA, 34293, Montpellier, France
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Awoonor-Williams E, Rowley CN. Evaluation of Methods for the Calculation of the pKa of Cysteine Residues in Proteins. J Chem Theory Comput 2016; 12:4662-73. [DOI: 10.1021/acs.jctc.6b00631] [Citation(s) in RCA: 65] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Ernest Awoonor-Williams
- Department of Chemistry, Memorial University of Newfoundland, St.
John’s, Newfoundland and Labrador A1B 3X9, Canada
| | - Christopher N. Rowley
- Department of Chemistry, Memorial University of Newfoundland, St.
John’s, Newfoundland and Labrador A1B 3X9, Canada
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Kim G, Levine RL. A Methionine Residue Promotes Hyperoxidation of the Catalytic Cysteine of Mouse Methionine Sulfoxide Reductase A. Biochemistry 2016; 55:3586-93. [PMID: 27259041 PMCID: PMC5020372 DOI: 10.1021/acs.biochem.6b00180] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Methionine sulfoxide reductase A (msrA) reduces methionine sulfoxide in proteins back to methionine. Its catalytic cysteine (Cys72-SH) has a low pKa that facilitates oxidation by methionine sulfoxide to cysteine sulfenic acid. If the catalytic cycle proceeds efficiently, the sulfenic acid is reduced back to cysteine at the expense of thioredoxin. However, the sulfenic acid is vulnerable to "irreversible" oxidation to cysteine sulfinic acid that inactivates msrA (hyperoxidation). We observed that human msrA is resistant to hyperoxidation while mouse msrA is readily hyperoxidized by micromolar concentrations of hydrogen peroxide. We investigated the basis of this difference in susceptibility to hyperoxidation and established that it is controlled by the presence or absence of a Met residue in the carboxyl-terminal domain of the enzyme, Met229. This residue is Val in human msrA, and when it was mutated to Met, human msrA became sensitive to hyperoxidation. Conversely, mouse msrA was rendered insensitive to hyperoxidation when Met229 was mutated to Val or one of five other residues. Positioning of the methionine at residue 229 is not critical, as hyperoxidation occurred as long as the methionine was located within the group of 14 carboxyl-terminal residues. The carboxyl domain of msrA is known to be flexible and to have access to the active site, and Met residues are known to form stable, noncovalent bonds with aromatic residues through interaction of the sulfur atom with the aromatic ring. We propose that Met229 forms such a bond with Trp74 at the active site, preventing formation of a protective sulfenylamide with Cys72 sulfenic acid. As a consequence, the sulfenic acid is available for facile, irreversible oxidation to cysteine sulfinic acid.
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Affiliation(s)
- Geumsoo Kim
- Laboratory of Biochemistry, National Heart, Lung, and Blood Institute Bethesda, MD 20892-8012
| | - Rodney L. Levine
- Laboratory of Biochemistry, National Heart, Lung, and Blood Institute Bethesda, MD 20892-8012
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Evidence for the dimerization-mediated catalysis of methionine sulfoxide reductase A from Clostridium oremlandii. PLoS One 2015; 10:e0131523. [PMID: 26107511 PMCID: PMC4479559 DOI: 10.1371/journal.pone.0131523] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2015] [Accepted: 06/02/2015] [Indexed: 11/30/2022] Open
Abstract
Clostridium oremlandii MsrA (CoMsrA) is a natively selenocysteine-containing methionine-S-sulfoxide reductase and classified into a 1-Cys type MsrA. CoMsrA exists as a monomer in solution. Herein, we report evidence that CoMsrA can undergo homodimerization during catalysis. The monomeric CoMsrA dimerizes in the presence of its substrate methionine sulfoxide via an intermolecular disulfide bond between catalytic Cys16 residues. The dimeric CoMsrA is resolved by the reductant glutaredoxin, suggesting the relevance of dimerization in catalysis. The dimerization reaction occurs in a concentration- and time-dependent manner. In addition, the occurrence of homodimer formation in the native selenoprotein CoMsrA is confirmed. We also determine the crystal structure of the dimeric CoMsrA, having the dimer interface around the two catalytic Cys16 residues. A central cone-shaped hole is present in the surface model of dimeric structure, and the two Cys16 residues constitute the base of the hole. Collectively, our biochemical and structural analyses suggest a novel dimerization-mediated mechanism for CoMsrA catalysis that is additionally involved in CoMsrA regeneration by glutaredoxin.
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Ghesquière B, Gevaert K. Proteomics methods to study methionine oxidation. MASS SPECTROMETRY REVIEWS 2014; 33:147-56. [PMID: 24178673 DOI: 10.1002/mas.21386] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/20/2012] [Revised: 04/26/2013] [Accepted: 04/30/2013] [Indexed: 05/10/2023]
Abstract
The oxidation and consequent reduction of protein-bound methionine residues is of great interest in understanding different aspects of how oxidative stress affects protein functions and cellular signaling. To date, few technologies are available for the study of methionine sulfoxides. And, especially the absence of highly specific antibodies has impeded the field in understanding the exact role of methionine oxidation on a proteome-wide level. Nonetheless, the different models where the responsible enzymes for repair of the oxidized methionines have been studied show that there is an important role for this modification in a cellular context. We here review different mass spectrometry based and proteomics methods for characterizing in vivo methionine oxidation.
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Affiliation(s)
- Bart Ghesquière
- Department of Medical Protein Research, VIB, B-9000, Ghent, Belgium; Department of Biochemistry, Ghent University, B-9000, Ghent, Belgium
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Lee EH, Kwak GH, Kim MJ, Kim HY, Hwang KY. Structural analysis of 1-Cys type selenoprotein methionine sulfoxide reductase A. Arch Biochem Biophys 2014; 545:1-8. [DOI: 10.1016/j.abb.2013.12.024] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2013] [Revised: 12/23/2013] [Accepted: 12/30/2013] [Indexed: 11/15/2022]
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Kim G, Weiss SJ, Levine RL. Methionine oxidation and reduction in proteins. BIOCHIMICA ET BIOPHYSICA ACTA 2014; 1840:901-5. [PMID: 23648414 PMCID: PMC3766491 DOI: 10.1016/j.bbagen.2013.04.038] [Citation(s) in RCA: 186] [Impact Index Per Article: 18.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/05/2013] [Revised: 04/24/2013] [Accepted: 04/27/2013] [Indexed: 01/10/2023]
Abstract
BACKGROUND Cysteine and methionine are the two sulfur containing amino acids in proteins. While the roles of protein-bound cysteinyl residues as endogenous antioxidants are well appreciated, those of methionine remain largely unexplored. SCOPE We summarize the key roles of methionine residues in proteins. MAJOR CONCLUSION Recent studies establish that cysteine and methionine have remarkably similar functions. GENERAL SIGNIFICANCE Both cysteine and methionine serve as important cellular antioxidants, stabilize the structure of proteins, and can act as regulatory switches through reversible oxidation and reduction. This article is part of a Special Issue entitled Current methods to study reactive oxygen species - pros and cons and biophysics of membrane proteins. Guest Editor: Christine Winterbourn.
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Affiliation(s)
- Geumsoo Kim
- Laboratory of Biochemistry, National Heart, Lung, and Blood Institute, Bethesda, Maryland 20892, USA
| | - Stephen J. Weiss
- Division of Molecular Medicine and Genetics, Department of Internal Medicine, Life Sciences Institute, University of Michigan, Ann Arbor, MI 48109, USA
| | - Rodney L. Levine
- Laboratory of Biochemistry, National Heart, Lung, and Blood Institute, Bethesda, Maryland 20892, USA
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Lim JC, Kim G, Levine RL. Stereospecific oxidation of calmodulin by methionine sulfoxide reductase A. Free Radic Biol Med 2013; 61:257-64. [PMID: 23583331 PMCID: PMC3745524 DOI: 10.1016/j.freeradbiomed.2013.04.004] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/18/2013] [Revised: 04/01/2013] [Accepted: 04/03/2013] [Indexed: 10/26/2022]
Abstract
Methionine sulfoxide reductase A has long been known to reduce S-methionine sulfoxide, both as a free amino acid and within proteins. Recently the enzyme was shown to be bidirectional, capable of oxidizing free methionine and methionine in proteins to S-methionine sulfoxide. A feasible mechanism for controlling the directionality has been proposed, raising the possibility that reversible oxidation and reduction of methionine residues within proteins is a redox-based mechanism for cellular regulation. We undertook studies aimed at identifying proteins that are subject to site-specific, stereospecific oxidation and reduction of methionine residues. We found that calmodulin, which has nine methionine residues, is such a substrate for methionine sulfoxide reductase A. When calmodulin is in its calcium-bound form, Met77 is oxidized to S-methionine sulfoxide by methionine sulfoxide reductase A. When methionine sulfoxide reductase A operates in the reducing direction, the oxidized calmodulin is fully reduced back to its native form. We conclude that reversible covalent modification of Met77 may regulate the interaction of calmodulin with one or more of its many targets.
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Affiliation(s)
- Jung Chae Lim
- Laboratory of Biochemistry, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Geumsoo Kim
- Laboratory of Biochemistry, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Rodney L Levine
- Laboratory of Biochemistry, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD 20892, USA.
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Tarrago L, Gladyshev VN. Recharging oxidative protein repair: catalysis by methionine sulfoxide reductases towards their amino acid, protein, and model substrates. BIOCHEMISTRY (MOSCOW) 2013; 77:1097-107. [PMID: 23157290 DOI: 10.1134/s0006297912100021] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
The sulfur-containing amino acid methionine (Met) in its free and amino acid residue forms can be readily oxidized to the R and S diastereomers of methionine sulfoxide (MetO). Methionine sulfoxide reductases A (MSRA) and B (MSRB) reduce MetO back to Met in a stereospecific manner, acting on the S and R forms, respectively. A third MSR type, fRMSR, reduces the R form of free MetO. MSRA and MSRB are spread across the three domains of life, whereas fRMSR is restricted to bacteria and unicellular eukaryotes. These enzymes protect against abiotic and biotic stresses and regulate lifespan. MSRs are thiol oxidoreductases containing catalytic redox-active cysteine or selenocysteine residues, which become oxidized by the substrate, requiring regeneration for the next catalytic cycle. These enzymes can be classified according to the number of redox-active cysteines (selenocysteines) and the strategies to regenerate their active forms by thioredoxin and glutaredoxin systems. For each MSR type, we review catalytic parameters for the reduction of free MetO, low molecular weight MetO-containing compounds, and oxidized proteins. Analysis of these data reinforces the concept that MSRAs reduce various types of MetO-containing substrates with similar efficiency, whereas MSRBs are specialized for the reduction of MetO in proteins.
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Affiliation(s)
- L Tarrago
- Brigham and Women's Hospital and Harvard Medical School, 77 Ave. Louis Pasteur, Boston, MA 02115, USA
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Jacques S, Ghesquière B, Van Breusegem F, Gevaert K. Plant proteins under oxidative attack. Proteomics 2013; 13:932-40. [DOI: 10.1002/pmic.201200237] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2012] [Revised: 09/27/2012] [Accepted: 10/22/2012] [Indexed: 11/09/2022]
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15
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Lim JC, Gruschus JM, Kim G, Berlett BS, Tjandra N, Levine RL. A low pKa cysteine at the active site of mouse methionine sulfoxide reductase A. J Biol Chem 2012; 287:25596-601. [PMID: 22661719 DOI: 10.1074/jbc.m112.369116] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Methionine sulfoxide reductase A is an essential enzyme in the antioxidant system which scavenges reactive oxygen species through cyclic oxidation and reduction of methionine and methionine sulfoxide. Recently it has also been shown to catalyze the reverse reaction, oxidizing methionine residues to methionine sulfoxide. A cysteine at the active site of the enzyme is essential for both reductase and oxidase activities. This cysteine has been reported to have a pK(a) of 9.5 in the absence of substrate, decreasing to 5.7 upon binding of substrate. Using three independent methods, we show that the pK(a) of the active site cysteine of mouse methionine sulfoxide reductase is 7.2 even in the absence of substrate. The primary mechanism by which the pK(a) is lowered is hydrogen bonding of the active site Cys-72 to protonated Glu-115. The low pK(a) renders the active site cysteine susceptible to oxidation to sulfenic acid by micromolar concentrations of hydrogen peroxide. This characteristic supports a role for methionine sulfoxide reductase in redox signaling.
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Affiliation(s)
- Jung Chae Lim
- Laboratory of Biochemistry, NHLBI, National Institutes of Health, Bethesda, Maryland 20892-8012, USA
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