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Zhang Q, Fan S, Tang M, Wang C, Li X, Jin Y, Yang Z. Computation-Guided Rational Design of Cysteine-Less Protein Variants in Engineered hCGL. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2024; 72:9937-9946. [PMID: 38651303 DOI: 10.1021/acs.jafc.3c06821] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/25/2024]
Abstract
The engineered human cystathionine-γ-lyase (hCGL) resulting in enhanced activity toward both cysteine and cystine unveils a potential robust antitumor activity. However, the presence of cysteine residues has the potential to induce oligomerization or incorrect disulfide bonding, which may decrease the bioavailability of biopharmaceuticals. Through a meticulous design process targeting the cysteine residues within engineered hCGL, a set of potential beneficial mutants were obtained by virtual screening employing Rosetta and ABACUS. Experimental measurements have revealed that most of the mutants showed increased activity toward both substrates l-Cys and CSSC. Furthermore, mutants C109V and C229D demonstrated Tm value increases of 8.2 and 1.8 °C, respectively. After an 80 min incubation at 60 °C, mutant C229D still maintained high residual activity. Unexpectedly, mutant C109V, displaying activity approximately 2-fold higher than the activity of wild type (WT) for both substrates, showed disappointing instability in plasma, which suggests that computational design still requires further consideration. Analysis of their structure and molecular dynamics (MD) simulation revealed the impact of hydrophobic interaction, hydrogen bonds, and near-attack conformation (NAC) stability on activity and stability. This study acquired information about mutants that exhibit enhanced activity or thermal resistance and serve as valuable guidance for subsequent specific cysteine modifications.
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Affiliation(s)
- Qian Zhang
- NHC Key Laboratory of Biotechnology of Antibiotics, Institute of Medicinal Biotechnology, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing 100050, China
| | - Shuai Fan
- NHC Key Laboratory of Biotechnology of Antibiotics, Institute of Medicinal Biotechnology, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing 100050, China
| | - Mengjia Tang
- School of Pharmacy, North China University of Science and Technology, Tangshan 063210, Hebei, China
| | - Chenyu Wang
- School of Pharmacy, North China University of Science and Technology, Tangshan 063210, Hebei, China
| | - Xiaoxiao Li
- School of Pharmacy, North China University of Science and Technology, Tangshan 063210, Hebei, China
| | - Yuanyuan Jin
- NHC Key Laboratory of Biotechnology of Antibiotics, Institute of Medicinal Biotechnology, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing 100050, China
| | - Zhaoyong Yang
- NHC Key Laboratory of Biotechnology of Antibiotics, Institute of Medicinal Biotechnology, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing 100050, China
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Nguyen TTP, Nguyen PL, Park SH, Jung CH, Jeon TI. Hydrogen Sulfide and Liver Health: Insights into Liver Diseases. Antioxid Redox Signal 2024; 40:122-144. [PMID: 37917113 DOI: 10.1089/ars.2023.0404] [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] [Indexed: 11/03/2023]
Abstract
Significance: Hydrogen sulfide (H2S) is a recently recognized gasotransmitter involved in physiological and pathological conditions in mammals. It protects organs from oxidative stress, inflammation, hypertension, and cell death. With abundant expression of H2S-production enzymes, the liver is closely linked to H2S signaling. Recent Advances: Hepatic H2S comes from various sources, including gut microbiota, exogenous sulfur salts, and endogenous production. Recent studies highlight the importance of hepatic H2S in liver diseases such as nonalcoholic fatty liver disease (NAFLD), liver injury, and cancer, particularly at advanced stages. Endogenous H2S production deficiency is associated with severe liver disease, while exogenous H2S donors protect against liver dysfunction. Critical Issues: However, the roles of H2S in NAFLD, liver injury, and liver cancer are still debated, and its effects depend on donor type, dosage, treatment duration, and cell type, suggesting a multifaceted role. This review aimed to critically evaluate H2S production, metabolism, mode of action, and roles in liver function and disease. Future Direction: Understanding H2S's precise roles and mechanisms in liver health will advance potential therapeutic applications in preclinical and clinical research. Targeting H2S-producing enzymes and exogenous H2S sources, alone or in combination with other drugs, could be explored. Quantifying endogenous H2S levels may aid in diagnosing and managing liver diseases. Antioxid. Redox Signal. 40, 122-144.
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Affiliation(s)
- Thuy T P Nguyen
- Department of Animal Science, College of Agriculture and Life Science, Chonnam National University, Gwangju, Republic of Korea
- Division of Radiation and Genome Stability, Department of Radiation Oncology, Dana-Farber Cancer Institute, Harvard Medical School, Boston, Massachusetts, USA
| | - Phuc L Nguyen
- Department of Animal Science, College of Agriculture and Life Science, Chonnam National University, Gwangju, Republic of Korea
| | - So-Hyun Park
- Aging and Metabolism Research Group, Korea Food Research Institute, Wanju-gun, Republic of Korea
| | - Chang Hwa Jung
- Aging and Metabolism Research Group, Korea Food Research Institute, Wanju-gun, Republic of Korea
| | - Tae-Il Jeon
- Department of Animal Science, College of Agriculture and Life Science, Chonnam National University, Gwangju, Republic of Korea
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Urrutia PJ, Bórquez DA. Expanded bioinformatic analysis of Oximouse dataset reveals key putative processes involved in brain aging and cognitive decline. Free Radic Biol Med 2023; 207:200-211. [PMID: 37473875 DOI: 10.1016/j.freeradbiomed.2023.07.018] [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: 05/31/2023] [Revised: 07/11/2023] [Accepted: 07/17/2023] [Indexed: 07/22/2023]
Abstract
The theory that aging is driven by the damage produced by reactive oxygen species (ROS) derived from oxidative metabolism dominated geroscience studies during the second half of the 20th century. However, increasing evidence that ROS also plays a key role in the physiological regulation of numerous processes through the reversible oxidation of cysteine residues in proteins, has challenged this notion. Currently, the scope of redox signaling has reached proteomic dimensions through mass spectrometry techniques. Here, we perform a comprehensive bioinformatics analysis of cysteine oxidation changes during mouse brain aging, using the quantitative data provided in the Oximouse dataset. Interestingly, our unbiased analysis identified hundreds of putative cysteine redox switches covering several pathways previously associated with aging. These include the ubiquitin-proteasome pathway and one-carbon metabolism (folate cycle, methionine cycle, transsulfuration and polyamine pathways). Surprisingly, cysteine oxidation changes are enriched in synaptic proteins in a highly asymmetric distribution: while postsynaptic proteins tend to increase cysteine oxidation with age, the opposite occurs for presynaptic proteins. Additionally, cysteine oxidation changes during aging are associated with proteins involved in the regulation of the mitochondrial transition pore opening and synaptic calcium homeostasis. Our analysis reinforces the concept that brain aging is associated with selective changes in the oxidation state of key proteins, rather than an overall trend toward increased oxidation. Also, we provide a prioritized list of specific cysteine residues with putative impact in aging processes for future experimental validation.
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Affiliation(s)
- Pamela J Urrutia
- Institute for Nutrition & Food Technology (INTA), Universidad de Chile, El Líbano 5524, Santiago, 7830490, Chile; Geroscience Center for Brain Health and Metabolism, Santiago, 7800003, Chile
| | - Daniel A Bórquez
- Laboratory of Cell Signaling & Bioinformatics, Center for Biomedical Research, Faculty of Medicine, Universidad Diego Portales, Ejército Libertador 141, Santiago, 8370007, Chile.
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Araki S, Takata T, Ono K, Sawa T, Kasamatsu S, Ihara H, Kumagai Y, Akaike T, Watanabe Y, Tsuchiya Y. Cystathionine γ-Lyase Self-Inactivates by Polysulfidation during Cystine Metabolism. Int J Mol Sci 2023; 24:9982. [PMID: 37373128 DOI: 10.3390/ijms24129982] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2023] [Revised: 06/06/2023] [Accepted: 06/08/2023] [Indexed: 06/29/2023] Open
Abstract
Cystathionine γ-lyase (CSE) is an enzyme responsible for the biosynthesis of cysteine from cystathionine in the final step of the transsulfuration pathway. It also has β-lyase activity toward cystine, generating cysteine persulfide (Cys-SSH). The chemical reactivity of Cys-SSH is thought to be involved in the catalytic activity of particular proteins via protein polysulfidation, the formation of -S-(S)n-H on their reactive cysteine residues. The Cys136/171 residues of CSE have been proposed to be redox-sensitive residues. Herein, we investigated whether CSE polysulfidation occurs at Cys136/171 during cystine metabolism. Transfection of wild-type CSE into COS-7 cells resulted in increased intracellular Cys-SSH production, which was significantly increased when Cys136Val or Cys136/171Val CSE mutants were transfected, instead of the wild-type enzyme. A biotin-polyethylene glycol-conjugated maleimide capture assay revealed that CSE polysulfidation occurs at Cys136 during cystine metabolism. In vitro incubation of CSE with CSE-enzymatically synthesized Cys-SSH resulted in the inhibition of Cys-SSH production. In contrast, the mutant CSEs (Cys136Val and Cys136/171Val) proved resistant to inhibition. The Cys-SSH-producing CSE activity of Cys136/171Val CSE was higher than that of the wild-type enzyme. Meanwhile, the cysteine-producing CSE activity of this mutant was equivalent to that of the wild-type enzyme. It is assumed that Cys-SSH-producing CSE activity could be auto-inactivated via the polysulfidation of the enzyme during cystine metabolism. Thus, the polysulfidation of CSE at the Cys136 residue may be an integral feature of cystine metabolism, which functions to down-regulate Cys-SSH synthesis by the enzyme.
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Affiliation(s)
- Shoma Araki
- Department of Pharmacology, Showa Pharmaceutical University, Machida 194-8543, Japan
| | - Tsuyoshi Takata
- Department of Pharmacology, Showa Pharmaceutical University, Machida 194-8543, Japan
- South Bend Campus, Indiana University School of Medicine, South Bend, IN 46617, USA
| | - Katsuhiko Ono
- Department of Microbiology, Graduate School of Medical Sciences, Kumamoto University, Kumamoto 860-8556, Japan
| | - Tomohiro Sawa
- Department of Microbiology, Graduate School of Medical Sciences, Kumamoto University, Kumamoto 860-8556, Japan
| | - Shingo Kasamatsu
- Department of Biological Chemistry, Graduate School of Science, Osaka Metropolitan University, Sakai 599-8531, Japan
| | - Hideshi Ihara
- Department of Biological Chemistry, Graduate School of Science, Osaka Metropolitan University, Sakai 599-8531, Japan
| | - Yoshito Kumagai
- Graduate School of Pharmaceutical Sciences, Kyusyu University, Fukuoka 812-8582, Japan
| | - Takaaki Akaike
- Department of Environmental Medicine and Molecular Toxicology, Graduate School of Medicine, Tohoku University, Sendai 980-8575, Japan
| | - Yasuo Watanabe
- Department of Pharmacology, Showa Pharmaceutical University, Machida 194-8543, Japan
| | - Yukihiro Tsuchiya
- Department of Pharmacology, Showa Pharmaceutical University, Machida 194-8543, Japan
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Gupta R, Sahu M, Tripathi R, Ambasta RK, Kumar P. Protein S-sulfhydration: Unraveling the prospective of hydrogen sulfide in the brain, vasculature and neurological manifestations. Ageing Res Rev 2022; 76:101579. [PMID: 35124235 DOI: 10.1016/j.arr.2022.101579] [Citation(s) in RCA: 22] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2021] [Revised: 01/30/2022] [Accepted: 02/01/2022] [Indexed: 02/08/2023]
Abstract
Hydrogen sulfide (H2S) and hydrogen polysulfides (H2Sn) are essential regulatory signaling molecules generated by the entire body, including the central nervous system. Researchers have focused on the classical H2S signaling from the past several decades, whereas the last decade has shown the emergence of H2S-induced protein S-sulfhydration signaling as a potential therapeutic approach. Cysteine S-persulfidation is a critical paradigm of post-translational modification in the process of H2S signaling. Additionally, studies have shown the cross-relationship between S-sulfhydration and other cysteine-induced post-translational modifications, namely nitrosylation and carbonylation. In the central nervous system, S-sulfhydration is involved in the cytoprotection through various signaling pathways, viz. inflammatory response, oxidative stress, endoplasmic reticulum stress, atherosclerosis, thrombosis, and angiogenesis. Further, studies have demonstrated H2S-induced S-sulfhydration in regulating different biological processes, such as mitochondrial integrity, calcium homeostasis, blood-brain permeability, cerebral blood flow, and long-term potentiation. Thus, protein S-sulfhydration becomes a crucial regulatory molecule in cerebrovascular and neurodegenerative diseases. Herein, we first described the generation of intracellular H2S followed by the application of H2S in the regulation of cerebral blood flow and blood-brain permeability. Further, we described the involvement of S-sulfhydration in different biological and cellular functions, such as inflammatory response, mitochondrial integrity, calcium imbalance, and oxidative stress. Moreover, we highlighted the importance of S-sulfhydration in cerebrovascular and neurodegenerative diseases.
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Ji D, Luo C, Liu J, Cao Y, Wu J, Yan W, Xue K, Chai J, Zhu X, Wu Y, Liu H, Wang W. Insufficient S-Sulfhydration of Methylenetetrahydrofolate Reductase Contributes to the Progress of Hyperhomocysteinemia. Antioxid Redox Signal 2022; 36:1-14. [PMID: 34409847 DOI: 10.1089/ars.2021.0029] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Aims: Hyperhomocysteinemia (HHcy) has been considered as a risk factor for cardiovascular disease, Alzheimer's disease, nonalcoholic fatty liver, and many other pathological conditions. Vitamin B6, Vitamin B12, and folate have been used to treat HHcy in clinics. However, at present, clinical therapies of HHcy display unsatisfactory effects. Here, we would like to explore a new mechanism involved in homocysteine (Hcy) metabolic disorders and a novel target for HHcy treatment. The key enzymes involved in Hcy metabolism deserve more insightful investigation. Methylenetetrahydrofolate reductase (MTHFR) is a key enzyme regulating the intracellular Hcy metabolism. Until now, the effect of post-translational modification on the bioactivity of MTHFR still remains unclear. This study aimed at exploring the relationship between MTHFR S-sulfhydration and its bioactivity, and at identifying the contribution of an elevated Hcy level on MTHFR bioactivity. Results: By both in vivo and in vitro studies, we observed the following results: (i) The bioactivity of MTHFR was positively associated with its S-sulfhydration level; (ii) MTHFR was modified at Cys32, Cys130, Cys131, Cys193, and Cys306 by S-sulfhydration under physiological conditions; (iii) Hydrogen sulfide (H2S) deficiency caused the decrease of MTHFR S-sulfhydration level and bioactivity in HHcy, which resulted in further aggravation of HHcy; and (iv) H2S donors reversed the decreased bioactivity of MTHFR in HHcy, thus reducing the excessive Hcy level. Innovation and Conclusion: Our study suggested that H2S could improve MTHFR bioactivity by S-sulfhydration, which might provide a candidate therapeutic strategy for HHcy. Antioxid. Redox Signal. 36, 1-14.
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Affiliation(s)
- Dengyu Ji
- Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Capital Medical University, Beijing, China.,Beijing Key Laboratory for Metabolic Disorder-Related Cardiovascular Diseases, Beijing, China
| | - Chenghua Luo
- Department of Pathology and Key Laboratory for Xinjiang Endemic and Ethnic Diseases, The First Affiliated Hospital, Shihezi University School of Medicine, Shihezi, China
| | - Jing Liu
- Department of Clinical Laboratory, Xuanwu Hospital, Capital Medical University, Beijing, China
| | - Yan Cao
- Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Capital Medical University, Beijing, China.,Beijing Key Laboratory for Metabolic Disorder-Related Cardiovascular Diseases, Beijing, China
| | - Jiangxu Wu
- Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Capital Medical University, Beijing, China.,Beijing Key Laboratory for Metabolic Disorder-Related Cardiovascular Diseases, Beijing, China
| | - Wenjing Yan
- Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Capital Medical University, Beijing, China.,Beijing Key Laboratory for Metabolic Disorder-Related Cardiovascular Diseases, Beijing, China
| | - Ke Xue
- Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Capital Medical University, Beijing, China.,Beijing Key Laboratory for Metabolic Disorder-Related Cardiovascular Diseases, Beijing, China
| | - Jiayin Chai
- Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Capital Medical University, Beijing, China.,Beijing Key Laboratory for Metabolic Disorder-Related Cardiovascular Diseases, Beijing, China
| | - Xinyu Zhu
- Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Capital Medical University, Beijing, China.,Beijing Key Laboratory for Metabolic Disorder-Related Cardiovascular Diseases, Beijing, China
| | - Ye Wu
- Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Capital Medical University, Beijing, China.,Beijing Key Laboratory for Metabolic Disorder-Related Cardiovascular Diseases, Beijing, China
| | - Huirong Liu
- Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Capital Medical University, Beijing, China.,Beijing Key Laboratory for Metabolic Disorder-Related Cardiovascular Diseases, Beijing, China
| | - Wen Wang
- Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Capital Medical University, Beijing, China.,Beijing Key Laboratory for Metabolic Disorder-Related Cardiovascular Diseases, Beijing, China
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7
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Liu F, Yu J, Zhang YX, Li F, Liu Q, Zhou Y, Huang S, Fang H, Xiao Z, Liao L, Xu J, Wu XY, Wu F. High-throughput tandem-microwell assay for ammonia repositions FDA-Approved drugs to inhibit Helicobacter pylori urease. FASEB J 2021; 35:e21967. [PMID: 34613630 DOI: 10.1096/fj.202100465rr] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2021] [Revised: 09/15/2021] [Accepted: 09/17/2021] [Indexed: 11/11/2022]
Abstract
To date, little attempt has been made to develop new treatments for Helicobacter pylori (H. pylori), although the community is aware of the shortage of treatments for H. pylori. In this study, we developed a 192-tandem-microwell-based high-throughput assay for ammonia that is a known virulence factor of H. pylori and a product of urease. We could identify few drugs, that is, panobinostat, dacinostat, ebselen, captan, and disulfiram, to potently inhibit the activity of ureases from bacterial or plant species. These inhibitors suppress the activity of urease via substrate-competitive or covalent-allosteric mechanism, but all except captan prevent the antibiotic-resistant H. pylori strain from killing human gastric cells, with a more pronounced effect than acetohydroxamic acid, a well-known urease inhibitor and clinically used drug for the treatment of bacterial infection. This study offers several bases for the development of new treatments for urease-containing pathogens and to study the mechanism responsible for the regulation of urease activity.
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Affiliation(s)
- Fan Liu
- Key Laboratory of Systems Biomedicine (Ministry of Education), Shanghai Center for Systems Biomedicine, Shanghai Jiao Tong University, Shanghai, China.,State Key Laboratory of Microbial Metabolism, Joint International Research Laboratory of Metabolic & Developmental Sciences, Sheng Yushou Center of Cell Biology and Immunology, School of Life Science and Biotechnology, Shanghai Jiao Tong University, Shanghai, China
| | - Jing Yu
- State Key Laboratory of Microbial Metabolism, Joint International Research Laboratory of Metabolic & Developmental Sciences, Sheng Yushou Center of Cell Biology and Immunology, School of Life Science and Biotechnology, Shanghai Jiao Tong University, Shanghai, China
| | - Yan-Xia Zhang
- School of Chemistry & Molecular Engineering, East China University of Science and Technology, Shanghai, China
| | - Fangzheng Li
- Key Laboratory of Systems Biomedicine (Ministry of Education), Shanghai Center for Systems Biomedicine, Shanghai Jiao Tong University, Shanghai, China.,State Key Laboratory of Natural Medicines, Department of Medicinal Chemistry, China Pharmaceutical University, Nanjing, China
| | - Qi Liu
- Hunan Engineering Laboratory for Analyse and Drugs Development of Ethnomedicine in Wuling Mountains, Jishou University, Hunan, China
| | - Yueyang Zhou
- Key Laboratory of Systems Biomedicine (Ministry of Education), Shanghai Center for Systems Biomedicine, Shanghai Jiao Tong University, Shanghai, China
| | - Shengshuo Huang
- State Key Laboratory of Microbial Metabolism, Joint International Research Laboratory of Metabolic & Developmental Sciences, Sheng Yushou Center of Cell Biology and Immunology, School of Life Science and Biotechnology, Shanghai Jiao Tong University, Shanghai, China
| | - Houqin Fang
- Shanghai Key Laboratory of Regulatory Biology, School of Life Sciences, East China Normal University, Shanghai, China
| | - Zhuping Xiao
- Hunan Engineering Laboratory for Analyse and Drugs Development of Ethnomedicine in Wuling Mountains, Jishou University, Hunan, China
| | - Lujian Liao
- Shanghai Key Laboratory of Regulatory Biology, School of Life Sciences, East China Normal University, Shanghai, China
| | - Jinyi Xu
- State Key Laboratory of Natural Medicines, Department of Medicinal Chemistry, China Pharmaceutical University, Nanjing, China
| | - Xin-Yan Wu
- School of Chemistry & Molecular Engineering, East China University of Science and Technology, Shanghai, China
| | - Fang Wu
- Key Laboratory of Systems Biomedicine (Ministry of Education), Shanghai Center for Systems Biomedicine, Shanghai Jiao Tong University, Shanghai, China
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Human Cystathionine γ-Lyase Is Inhibited by s-Nitrosation: A New Crosstalk Mechanism between NO and H 2S. Antioxidants (Basel) 2021; 10:antiox10091391. [PMID: 34573023 PMCID: PMC8467691 DOI: 10.3390/antiox10091391] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2021] [Revised: 08/20/2021] [Accepted: 08/25/2021] [Indexed: 01/01/2023] Open
Abstract
The ‘gasotransmitters’ hydrogen sulfide (H2S), nitric oxide (NO), and carbon monoxide (CO) act as second messengers in human physiology, mediating signal transduction via interaction with or chemical modification of protein targets, thereby regulating processes such as neurotransmission, blood flow, immunomodulation, or energy metabolism. Due to their broad reactivity and potential toxicity, the biosynthesis and breakdown of H2S, NO, and CO are tightly regulated. Growing evidence highlights the active role of gasotransmitters in their mutual cross-regulation. In human physiology, the transsulfuration enzymes cystathionine β-synthase (CBS) and cystathionine γ-lyase (CSE) are prominent H2S enzymatic sources. While CBS is known to be inhibited by NO and CO, little is known about CSE regulation by gasotransmitters. Herein, we investigated the effect of s-nitrosation on CSE catalytic activity. H2S production by recombinant human CSE was found to be inhibited by the physiological nitrosating agent s-nitrosoglutathione (GSNO), while reduced glutathione had no effect. GSNO-induced inhibition was partially reverted by ascorbate and accompanied by the disappearance of one solvent accessible protein thiol. By combining differential derivatization procedures and mass spectrometry-based analysis with functional assays, seven out of the ten protein cysteine residues, namely Cys84, Cys109, Cys137, Cys172, Cys229, Cys307, and Cys310, were identified as targets of s-nitrosation. By generating conservative Cys-to-Ser variants of the identified s-nitrosated cysteines, Cys137 was identified as most significantly contributing to the GSNO-mediated CSE inhibition. These results highlight a new mechanism of crosstalk between gasotransmitters.
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