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Zakrocka I, Targowska-Duda KM, Kocki T, Turski W, Urbańska EM, Załuska W. Loop diuretics inhibit kynurenic acid production and kynurenine aminotransferases activity in rat kidneys. Pharmacol Rep 2024:10.1007/s43440-024-00648-8. [PMID: 39261392 DOI: 10.1007/s43440-024-00648-8] [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: 07/09/2024] [Revised: 08/29/2024] [Accepted: 08/30/2024] [Indexed: 09/13/2024]
Abstract
BACKGROUND Loop diuretics became a cornerstone in the therapy of hypervolemia in patients with chronic kidney disease or heart failure. Apart from the influence on water and electrolyte balance, these drugs were shown to inhibit tissue fibrosis and renin-angiotensin-system activity. The kynurenine (KYN) pathway products are suggested to be uremic toxins. Kynurenic acid (KYNA) is synthesized by kynurenine aminotransferases (KATs) in the brain and periphery. The cardiovascular and renal effects of KYNA are well documented. However, high KYNA levels have been correlated with the rate of kidney damage and its complications. Our study aimed to assess the effect of loop diuretics, ethacrynic acid, furosemide, and torasemide on KYNA synthesis and KATs activity in rat kidneys in vitro. METHODS Quantitative analyses of KYNA were performed using fluorimetric HPLC detection. Additionally, molecular docking studies determined the possible interactions of investigated compounds with an active site of KAT I and KAT II. RESULTS All studied drugs inhibited KYNA production in rat kidneys in vitro at 0.5-1.0 mmol/l concentrations. Only ethacrynic acid at 1.0 mmol/l concentration significantly lowered KAT I and KAT II activity in kidney homogenates, whereas other drugs were ineffective. Molecular docking results indicated the common binding site for each of the studied loop diuretics and KYNA. They suggested possible residues involved in their binding to the active site of both KAT I and KAT II model. CONCLUSIONS Our study reveals that loop diuretics may decrease KYNA synthesis in rat kidneys in vitro. The presented results warrant further research in the context of KYN pathway activity regulation by loop diuretics.
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Affiliation(s)
- Izabela Zakrocka
- Department of Nephrology, Medical University of Lublin, Jaczewskiego 8, 20-954, Lublin, Poland.
| | | | - Tomasz Kocki
- Department of Experimental and Clinical Pharmacology, Medical University of Lublin, Jaczewskiego 8b, 20-090, Lublin, Poland
| | - Waldemar Turski
- Department of Experimental and Clinical Pharmacology, Medical University of Lublin, Jaczewskiego 8b, 20-090, Lublin, Poland
| | - Ewa M Urbańska
- Department of Experimental and Clinical Pharmacology, Medical University of Lublin, Jaczewskiego 8b, 20-090, Lublin, Poland
| | - Wojciech Załuska
- Department of Nephrology, Medical University of Lublin, Jaczewskiego 8, 20-954, Lublin, Poland
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2
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Koper K, Han SW, Kothadia R, Salamon H, Yoshikuni Y, Maeda HA. Multisubstrate specificity shaped the complex evolution of the aminotransferase family across the tree of life. Proc Natl Acad Sci U S A 2024; 121:e2405524121. [PMID: 38885378 PMCID: PMC11214133 DOI: 10.1073/pnas.2405524121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2024] [Accepted: 05/14/2024] [Indexed: 06/20/2024] Open
Abstract
Aminotransferases (ATs) are an ancient enzyme family that play central roles in core nitrogen metabolism, essential to all organisms. However, many of the AT enzyme functions remain poorly defined, limiting our fundamental understanding of the nitrogen metabolic networks that exist in different organisms. Here, we traced the deep evolutionary history of the AT family by analyzing AT enzymes from 90 species spanning the tree of life (ToL). We found that each organism has maintained a relatively small and constant number of ATs. Mapping the distribution of ATs across the ToL uncovered that many essential AT reactions are carried out by taxon-specific AT enzymes due to wide-spread nonorthologous gene displacements. This complex evolutionary history explains the difficulty of homology-based AT functional prediction. Biochemical characterization of diverse aromatic ATs further revealed their broad substrate specificity, unlike other core metabolic enzymes that evolved to catalyze specific reactions today. Interestingly, however, we found that these AT enzymes that diverged over billion years share common signatures of multisubstrate specificity by employing different nonconserved active site residues. These findings illustrate that AT family enzymes had leveraged their inherent substrate promiscuity to maintain a small yet distinct set of multifunctional AT enzymes in different taxa. This evolutionary history of versatile ATs likely contributed to the establishment of robust and diverse nitrogen metabolic networks that exist throughout the ToL. The study provides a critical foundation to systematically determine diverse AT functions and underlying nitrogen metabolic networks across the ToL.
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Affiliation(s)
- Kaan Koper
- Department of Botany, University of Wisconsin-Madison, Madison, WI53706
| | - Sang-Woo Han
- Environmental Genomics and Systems Biology Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720
- Department of Biotechnology, Konkuk University, Chungju27478, South Korea
| | - Ramani Kothadia
- The US Department of Energy Joint Genome Institute, Lawrence Berkeley National Laboratory, Berkeley, CA94720
| | - Hugh Salamon
- The US Department of Energy Joint Genome Institute, Lawrence Berkeley National Laboratory, Berkeley, CA94720
| | - Yasuo Yoshikuni
- Environmental Genomics and Systems Biology Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720
- The US Department of Energy Joint Genome Institute, Lawrence Berkeley National Laboratory, Berkeley, CA94720
- Biological Systems and Engineering Division, Lawrence Berkeley National Laboratory, Berkeley, CA94720
- Center for Advanced Bioenergy and Bioproducts Innovation, Lawrence Berkeley National Laboratory, Berkeley, CA94720
- Global Center for Food, Land, and Water Resources, Research Faculty of Agriculture, Hokkaido University, Hokkaido, Japan 060-8589
- Institute of Global Innovation Research, Tokyo University of Agriculture and Technology, Tokyo183-8538, Japan
| | - Hiroshi A. Maeda
- Department of Botany, University of Wisconsin-Madison, Madison, WI53706
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3
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Malatesta M, Fornasier E, Di Salvo ML, Tramonti A, Zangelmi E, Peracchi A, Secchi A, Polverini E, Giachin G, Battistutta R, Contestabile R, Percudani R. One substrate many enzymes virtual screening uncovers missing genes of carnitine biosynthesis in human and mouse. Nat Commun 2024; 15:3199. [PMID: 38615009 PMCID: PMC11016064 DOI: 10.1038/s41467-024-47466-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2023] [Accepted: 03/26/2024] [Indexed: 04/15/2024] Open
Abstract
The increasing availability of experimental and computational protein structures entices their use for function prediction. Here we develop an automated procedure to identify enzymes involved in metabolic reactions by assessing substrate conformations docked to a library of protein structures. By screening AlphaFold-modeled vitamin B6-dependent enzymes, we find that a metric based on catalytically favorable conformations at the enzyme active site performs best (AUROC Score=0.84) in identifying genes associated with known reactions. Applying this procedure, we identify the mammalian gene encoding hydroxytrimethyllysine aldolase (HTMLA), the second enzyme of carnitine biosynthesis. Upon experimental validation, we find that the top-ranked candidates, serine hydroxymethyl transferase (SHMT) 1 and 2, catalyze the HTMLA reaction. However, a mouse protein absent in humans (threonine aldolase; Tha1) catalyzes the reaction more efficiently. Tha1 did not rank highest based on the AlphaFold model, but its rank improved to second place using the experimental crystal structure we determined at 2.26 Å resolution. Our findings suggest that humans have lost a gene involved in carnitine biosynthesis, with HTMLA activity of SHMT partially compensating for its function.
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Affiliation(s)
- Marco Malatesta
- Department of Chemistry, Life Sciences and Environmental Sustainability, University of Parma, Parma, Italy
| | | | - Martino Luigi Di Salvo
- Istituto Pasteur Italia-Fondazione Cenci Bolognetti and Department of Biochemical Sciences "A. Rossi Fanelli", Sapienza University of Rome, Rome, Italy
| | - Angela Tramonti
- Institute of Molecular Biology and Pathology, Italian National Research Council, Rome, Italy
| | - Erika Zangelmi
- Department of Chemistry, Life Sciences and Environmental Sustainability, University of Parma, Parma, Italy
| | - Alessio Peracchi
- Department of Chemistry, Life Sciences and Environmental Sustainability, University of Parma, Parma, Italy
| | - Andrea Secchi
- Department of Chemistry, Life Sciences and Environmental Sustainability, University of Parma, Parma, Italy
| | - Eugenia Polverini
- Department of Mathematical, Physical and Computer Sciences, University of Parma, Parma, Italy
| | - Gabriele Giachin
- Department of Chemical Sciences, University of Padua, Padova, Italy
| | | | - Roberto Contestabile
- Istituto Pasteur Italia-Fondazione Cenci Bolognetti and Department of Biochemical Sciences "A. Rossi Fanelli", Sapienza University of Rome, Rome, Italy.
| | - Riccardo Percudani
- Department of Chemistry, Life Sciences and Environmental Sustainability, University of Parma, Parma, Italy.
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4
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Selvam AK, Jawad R, Gramignoli R, Achour A, Salter H, Björnstedt M. A Novel mRNA-Mediated and MicroRNA-Guided Approach to Specifically Eradicate Drug-Resistant Hepatocellular Carcinoma Cell Lines by Se-Methylselenocysteine. Antioxidants (Basel) 2021; 10:1094. [PMID: 34356326 PMCID: PMC8301172 DOI: 10.3390/antiox10071094] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2021] [Revised: 06/28/2021] [Accepted: 07/01/2021] [Indexed: 01/25/2023] Open
Abstract
Despite progress in the treatment of non-visceral malignancies, the prognosis remains poor for malignancies of visceral organs and novel therapeutic approaches are urgently required. We evaluated a novel therapeutic regimen based on treatment with Se-methylselenocysteine (MSC) and concomitant tumor-specific induction of Kynurenine aminotransferase 1 (KYAT1) in hepatocellular carcinoma (HCC) cell lines, using either vector-based and/or lipid nanoparticle-mediated delivery of mRNA. Supplementation of MSC in KYAT1 overexpressed cells resulted in significantly increased cytotoxicity, due to ROS formation, as compared to MSC alone. Furthermore, microRNA antisense-targeted sites for miR122, known to be widely expressed in normal hepatocytes while downregulated in hepatocellular carcinoma, were added to specifically limit cytotoxicity in HCC cells, thereby limiting the off-target effects. KYAT1 expression was significantly reduced in cells with high levels of miR122 supporting the concept of miR-guided induction of tumor-specific cytotoxicity. The addition of alpha-ketoacid favored the production of methylselenol, enhancing the cytotoxic efficacy of MSC in HCC cells, with no effects on primary human hepatocytes. Altogether, the proposed regimen offers great potential to safely and specifically target hepatic tumors that are currently untreatable.
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Affiliation(s)
- Arun Kumar Selvam
- Department of Laboratory Medicine, Division of Pathology, Karolinska Institutet, Karolinska University Hospital, S-141 86 Stockholm, Sweden; (A.K.S.); (R.J.); (R.G.); (H.S.)
| | - Rim Jawad
- Department of Laboratory Medicine, Division of Pathology, Karolinska Institutet, Karolinska University Hospital, S-141 86 Stockholm, Sweden; (A.K.S.); (R.J.); (R.G.); (H.S.)
| | - Roberto Gramignoli
- Department of Laboratory Medicine, Division of Pathology, Karolinska Institutet, Karolinska University Hospital, S-141 86 Stockholm, Sweden; (A.K.S.); (R.J.); (R.G.); (H.S.)
| | - Adnane Achour
- Science for Life Laboratory, Department of Medicine Solna, Karolinska Institute, & Division of Infectious Diseases, Karolinska University Hospital, SE-171 77 Solna, Sweden;
| | - Hugh Salter
- Department of Laboratory Medicine, Division of Pathology, Karolinska Institutet, Karolinska University Hospital, S-141 86 Stockholm, Sweden; (A.K.S.); (R.J.); (R.G.); (H.S.)
- Moderna, Inc., 200 Technology Square, Cambridge, MA 02139, USA
| | - Mikael Björnstedt
- Department of Laboratory Medicine, Division of Pathology, Karolinska Institutet, Karolinska University Hospital, S-141 86 Stockholm, Sweden; (A.K.S.); (R.J.); (R.G.); (H.S.)
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5
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Groth B, Venkatakrishnan P, Lin SJ. NAD + Metabolism, Metabolic Stress, and Infection. Front Mol Biosci 2021; 8:686412. [PMID: 34095234 PMCID: PMC8171187 DOI: 10.3389/fmolb.2021.686412] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2021] [Accepted: 05/05/2021] [Indexed: 12/26/2022] Open
Abstract
Nicotinamide adenine dinucleotide (NAD+) is an essential metabolite with wide-ranging and significant roles in the cell. Defects in NAD+ metabolism have been associated with many human disorders; it is therefore an emerging therapeutic target. Moreover, NAD+ metabolism is perturbed during colonization by a variety of pathogens, either due to the molecular mechanisms employed by these infectious agents or by the host immune response they trigger. Three main biosynthetic pathways, including the de novo and salvage pathways, contribute to the production of NAD+ with a high degree of conservation from bacteria to humans. De novo biosynthesis, which begins with l-tryptophan in eukaryotes, is also known as the kynurenine pathway. Intermediates of this pathway have various beneficial and deleterious effects on cellular health in different contexts. For example, dysregulation of this pathway is linked to neurotoxicity and oxidative stress. Activation of the de novo pathway is also implicated in various infections and inflammatory signaling. Given the dynamic flexibility and multiple roles of NAD+ intermediates, it is important to understand the interconnections and cross-regulations of NAD+ precursors and associated signaling pathways to understand how cells regulate NAD+ homeostasis in response to various growth conditions. Although regulation of NAD+ homeostasis remains incompletely understood, studies in the genetically tractable budding yeast Saccharomyces cerevisiae may help provide some molecular basis for how NAD+ homeostasis factors contribute to the maintenance and regulation of cellular function and how they are regulated by various nutritional and stress signals. Here we present a brief overview of recent insights and discoveries made with respect to the relationship between NAD+ metabolism and selected human disorders and infections, with a particular focus on the de novo pathway. We also discuss how studies in budding yeast may help elucidate the regulation of NAD+ homeostasis.
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Affiliation(s)
- Benjamin Groth
- Department of Microbiology and Molecular Genetics, College of Biological Sciences, University of California, Davis, Davis, CA, United States
| | - Padmaja Venkatakrishnan
- Department of Microbiology and Molecular Genetics, College of Biological Sciences, University of California, Davis, Davis, CA, United States
| | - Su-Ju Lin
- Department of Microbiology and Molecular Genetics, College of Biological Sciences, University of California, Davis, Davis, CA, United States
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6
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Lan J, Liu Z, Liao C, Merkler DJ, Han Q, Li J. A Study for Therapeutic Treatment against Parkinson's Disease via Chou's 5-steps Rule. Curr Top Med Chem 2019; 19:2318-2333. [PMID: 31629395 DOI: 10.2174/1568026619666191019111528] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2019] [Revised: 08/05/2019] [Accepted: 08/22/2019] [Indexed: 11/22/2022]
Abstract
The enzyme L-DOPA decarboxylase (DDC), also called aromatic-L-amino-acid decarboxylase, catalyzes the biosynthesis of dopamine, serotonin, and trace amines. Its deficiency or perturbations in expression result in severe motor dysfunction or a range of neurodegenerative and psychiatric disorders. A DDC substrate, L-DOPA, combined with an inhibitor of the enzyme is still the most effective treatment for symptoms of Parkinson's disease. In this review, we provide an update regarding the structures, functions, and inhibitors of DDC, particularly with regards to the treatment of Parkinson's disease. This information will provide insight into the pharmacological treatment of Parkinson's disease.
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Affiliation(s)
- Jianqiang Lan
- Key Laboratory of Tropical Biological Resources of Ministry of Education, School of Life and Pharmaceutical Sciences, Hainan University, Haikou, Hainan 570228, China
| | - Zhongqiang Liu
- Key Laboratory of Tropical Biological Resources of Ministry of Education, School of Life and Pharmaceutical Sciences, Hainan University, Haikou, Hainan 570228, China
| | - Chenghong Liao
- Key Laboratory of Tropical Biological Resources of Ministry of Education, School of Life and Pharmaceutical Sciences, Hainan University, Haikou, Hainan 570228, China
| | - David J Merkler
- Department of Chemistry, University of South Florida, Tampa, FL, 33620, United States
| | - Qian Han
- Key Laboratory of Tropical Biological Resources of Ministry of Education, School of Life and Pharmaceutical Sciences, Hainan University, Haikou, Hainan 570228, China
| | - Jianyong Li
- Department of Biochemistry, Virginia Tech, Blacksburg, VA 24061, United States
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7
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Abstract
Indoleamine 2,3-dioxygenase 1 (IDO1) catalyzes the first and rate-limiting reaction of l-tryptophan (Trp) conversion into l-kynurenine (Kyn). The depletion of Trp, and the accumulation of Kyn have been proposed as mechanisms that contribute to the suppression of the immune response-primarily evidenced by in vitro study. IDO1 is therefore considered to be an immunosuppressive modulator and quantification of IDO1 metabolism may be critical to understanding its role in select immunopathologies, including autoimmune- and oncological-conditions, as well as for determining the potency of IDO1 enzyme inhibitors. Because tryptophan 2,3-dioxygenase (TDO), and to a significantly lesser extent, IDO2, also catabolize Trp into Kyn, it's important to differentiate the contribution of each enzyme to Trp catabolism and Kyn generation. Moreover, a great variety of detection methods have been developed for the quantification of Trp metabolites, but choosing the suitable protocol remains challenging. Here, we review the differential expression of IDO1/TDO/IDO2 in normal and malignant tissues, followed by a comprehensive analysis of methodologies for quantifying Trp and Kyn in vitro and in vivo, with an emphasis on the advantages/disadvantages for each application.
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8
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Yoshida Y, Fujigaki H, Kato K, Yamazaki K, Fujigaki S, Kunisawa K, Yamamoto Y, Mouri A, Oda A, Nabeshima T, Saito K. Selective and competitive inhibition of kynurenine aminotransferase 2 by glycyrrhizic acid and its analogues. Sci Rep 2019; 9:10243. [PMID: 31308447 PMCID: PMC6629613 DOI: 10.1038/s41598-019-46666-y] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2019] [Accepted: 07/03/2019] [Indexed: 12/15/2022] Open
Abstract
The enzyme kynurenine aminotransferase (KAT) catalyses the conversion of kynurenine (KYN) to kynurenic acid (KYNA). Although the isozymes KAT1–4 have been identified, KYNA is mainly produced by KAT2 in brain tissues. KNYA is an antagonist of N-methyl-D-aspartate and α-7-nicotinic acetylcholine receptors, and accumulation of KYNA in the brain has been associated with the pathology of schizophrenia. Therefore, KAT2 could be exploited as a therapeutic target for the management of schizophrenia. Although currently available KAT2 inhibitors irreversibly bind to pyridoxal 5′-phosphate (PLP), inhibition via this mechanism may cause adverse side effects because of the presence of other PLP-dependent enzymes. Therefore, we identified novel selective KAT2 inhibitors by screening approximately 13,000 molecules. Among these, glycyrrhizic acid (GL) and its analogues, glycyrrhetinic acid (GA) and carbenoxolone (CBX), were identified as KAT2 inhibitors. These compounds were highly selective for KAT2 and competed with its substrate KYN, but had no effects on the other 3 KAT isozymes. Furthermore, we demonstrated that in complex structures that were predicted in docking calculations, GL, GA and CBX were located on the same surface as the aromatic ring of KYN. These results indicate that GL and its analogues are highly selective and competitive inhibitors of KAT2.
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Affiliation(s)
- Yukihiro Yoshida
- Department of Disease Control and Prevention, Fujita Health University Graduate School of Health Sciences, Aichi, 470-1192, Japan
| | - Hidetsugu Fujigaki
- Department of Disease Control and Prevention, Fujita Health University Graduate School of Health Sciences, Aichi, 470-1192, Japan.
| | - Koichi Kato
- College of Pharmacy, Kinjo Gakuin University, Aichi, 463-8521, Japan.,Faculty of Pharmacy, Meijo University, Aichi, 468-8503, Japan
| | - Kyoka Yamazaki
- Department of Disease Control and Prevention, Fujita Health University Graduate School of Health Sciences, Aichi, 470-1192, Japan
| | - Suwako Fujigaki
- Department of Disease Control and Prevention, Fujita Health University Graduate School of Health Sciences, Aichi, 470-1192, Japan
| | - Kazuo Kunisawa
- Advanced Diagnostic System Research Laboratory, Fujita Health University Graduate School of Health Sciences, Aichi, 470-1192, Japan
| | - Yasuko Yamamoto
- Department of Disease Control and Prevention, Fujita Health University Graduate School of Health Sciences, Aichi, 470-1192, Japan
| | - Akihiro Mouri
- Department of Regulatory Science, Fujita Health University Graduate School of Health Sciences, Aichi, 470-1192, Japan.,Japanese Drug Organization of Appropriate Use and Research, Aichi, 468-0069, Japan
| | - Akifumi Oda
- Faculty of Pharmacy, Meijo University, Aichi, 468-8503, Japan
| | - Toshitaka Nabeshima
- Advanced Diagnostic System Research Laboratory, Fujita Health University Graduate School of Health Sciences, Aichi, 470-1192, Japan.,Japanese Drug Organization of Appropriate Use and Research, Aichi, 468-0069, Japan
| | - Kuniaki Saito
- Department of Disease Control and Prevention, Fujita Health University Graduate School of Health Sciences, Aichi, 470-1192, Japan.,Advanced Diagnostic System Research Laboratory, Fujita Health University Graduate School of Health Sciences, Aichi, 470-1192, Japan.,Japanese Drug Organization of Appropriate Use and Research, Aichi, 468-0069, Japan.,Human Health Sciences, Graduate School of Medicine and Faculty of Medicine, Kyoto University, Kyoto, 606-8507, Japan
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9
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Han Q, Yang C, Lu J, Zhang Y, Li J. Metabolism of Oxalate in Humans: A Potential Role Kynurenine Aminotransferase/Glutamine Transaminase/Cysteine Conjugate Beta-lyase Plays in Hyperoxaluria. Curr Med Chem 2019; 26:4944-4963. [PMID: 30907303 DOI: 10.2174/0929867326666190325095223] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2018] [Revised: 02/17/2019] [Accepted: 02/22/2019] [Indexed: 11/22/2022]
Abstract
Hyperoxaluria, excessive urinary oxalate excretion, is a significant health problem worldwide. Disrupted oxalate metabolism has been implicated in hyperoxaluria and accordingly, an enzymatic disturbance in oxalate biosynthesis can result in the primary hyperoxaluria. Alanine glyoxylate aminotransferase-1 and glyoxylate reductase, the enzymes involving glyoxylate (precursor for oxalate) metabolism, have been related to primary hyperoxalurias. Some studies suggest that other enzymes such as glycolate oxidase and alanine glyoxylate aminotransferase-2 might be associated with primary hyperoxaluria as well, but evidence of a definitive link is not strong between the clinical cases and gene mutations. There are still some idiopathic hyperoxalurias, which require a further study for the etiologies. Some aminotransferases, particularly kynurenine aminotransferases, can convert glyoxylate to glycine. Based on biochemical and structural characteristics, expression level, subcellular localization of some aminotransferases, a number of them appear able to catalyze the transamination of glyoxylate to glycine more efficiently than alanine glyoxylate aminotransferase-1. The aim of this minireview is to explore other undermining causes of primary hyperoxaluria and stimulate research toward achieving a comprehensive understanding of underlying mechanisms leading to the disease. Herein, we reviewed all aminotransferases in the liver for their functions in glyoxylate metabolism. Particularly, kynurenine aminotransferase-I and III were carefully discussed regarding their biochemical and structural characteristics, cellular localization, and enzyme inhibition. Kynurenine aminotransferase-III is, so far, the most efficient putative mitochondrial enzyme to transaminate glyoxylate to glycine in mammalian livers, might be an interesting enzyme to look over in hyperoxaluria etiology of primary hyperoxaluria and should be carefully investigated for its involvement in oxalate metabolism.
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Affiliation(s)
- Qian Han
- Key Laboratory of Tropical Biological Resources of Ministry of Education, Hainan University, Haikou, Hainan 570228. China
| | - Cihan Yang
- Key Laboratory of Tropical Biological Resources of Ministry of Education, Hainan University, Haikou, Hainan 570228. China
| | - Jun Lu
- Central South University Xiangya School of Medicine Affiliated Haikou People's Hospital, Haikou, Hainan 570208. China
| | - Yinai Zhang
- Central South University Xiangya School of Medicine Affiliated Haikou People's Hospital, Haikou, Hainan 570208. China
| | - Jianyong Li
- Department of Biochemistry, Virginia Tech, Blacksburg, VA 24061. United States
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10
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Rossi F, Miggiano R, Ferraris DM, Rizzi M. The Synthesis of Kynurenic Acid in Mammals: An Updated Kynurenine Aminotransferase Structural KATalogue. Front Mol Biosci 2019; 6:7. [PMID: 30873412 PMCID: PMC6400995 DOI: 10.3389/fmolb.2019.00007] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2018] [Accepted: 02/06/2019] [Indexed: 01/25/2023] Open
Abstract
Kynurenic acid (KYNA) is a bioactive compound that is produced along the kynurenine pathway (KP) during tryptophan degradation. In a few decades, KYNA shifted from being regarded a poorly characterized by-product of the KP to being considered a main player in many aspects of mammalian physiology, including the control of glutamatergic and cholinergic synaptic transmission, and the coordination of immunomodulation. The renewed attention being paid to the study of KYNA homeostasis is justified by the discovery of selective and potent inhibitors of kynurenine aminotransferase II, which is considered the main enzyme responsible for KYNA synthesis in the mammalian brain. Since abnormally high KYNA levels in the central nervous system have been associated with schizophrenia and cognitive impairment, these inhibitors promise the development of novel anti-psychotic and pro-cognitive drugs. Here, we summarize the currently available structural information on human and rodent kynurenine aminotransferases (KATs) as the result of global efforts aimed at describing the full complement of mammalian isozymes. These studies highlight peculiar features of KATs that can be exploited for the development of isozyme-specific inhibitors. Together with the optimization of biochemical assays to measure individual KAT activities in complex samples, this wealth of knowledge will continue to foster the identification and rational design of brain penetrant small molecules to attenuate KYNA synthesis, i.e., molecules capable of lowering KYNA levels without exposing the brain to the harmful withdrawal of KYNA-dependent neuroprotective actions.
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Affiliation(s)
- Franca Rossi
- Biochemistry and Biocrystallography Unit, DSF-Dipartimento di Scienze del Farmaco, University of Piemonte Orientale, Novara, Italy
| | - Riccardo Miggiano
- Biochemistry and Biocrystallography Unit, DSF-Dipartimento di Scienze del Farmaco, University of Piemonte Orientale, Novara, Italy
| | - Davide M Ferraris
- Biochemistry and Biocrystallography Unit, DSF-Dipartimento di Scienze del Farmaco, University of Piemonte Orientale, Novara, Italy
| | - Menico Rizzi
- Biochemistry and Biocrystallography Unit, DSF-Dipartimento di Scienze del Farmaco, University of Piemonte Orientale, Novara, Italy
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11
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Thiyagarajamoorthy DK, Arulanandam CD, Dahms HU, Murugaiah SG, Krishnan M, Rathinam AJ. Marine Bacterial Compounds Evaluated by In Silico Studies as Antipsychotic Drugs Against Schizophrenia. MARINE BIOTECHNOLOGY (NEW YORK, N.Y.) 2018; 20:639-653. [PMID: 30019186 DOI: 10.1007/s10126-018-9835-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/12/2018] [Accepted: 05/24/2018] [Indexed: 06/08/2023]
Abstract
Schizophrenia (SCZ) is one of the brain disorders which affects the thinking and behavioral skills of patients. This disorder comes along with an overproduction of kynurenic acid in the cerebrospinal fluid and the prefrontal cortex of SCZ patients. In this study, marine bacterial compounds were screened for their suitability as antagonists against human kynurenine aminotransferase (hKAT-1) which causes the synthesis of kynurenic acid downstream which ultimately causes the SCZ disorder according to the kynurenic hypothesis of SCZ. The marine actinobacterial compound bonactin shows more promising results than other tested marine compounds such as the histamine H2 blocker famotidine and indole-3-acetic acid (IAC) from docking and in silico toxicological studies carried out here. The obtained results of the Grid-based Ligand Docking with Energetics (Glide) scores of extra-precision (XP) Glide against the target protein hKAT-1 on IAC, famotidine, and bonactin were - 6.581, - 6.500 and - 7.730 kcal/mol where Glide energies were - 29.84, - 28.391, and - 47.565 kcal/mol, respectively. Bonactin is known as an antibacterial and antifungal compound being extracted from a marine Streptomyces sp. Comparing tested compounds against the drug target hKAT-1, bonactin alone showed the best Glide score and Glide energy on the target protein hKAT-1.
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Affiliation(s)
| | - Charli Deepak Arulanandam
- Department of Biomedical Science and Environmental Biology, KMU- Kaohsiung Medical University, Kaohsiung, 80708, Taiwan, Republic Of China
- Department of Medicinal and Applied Chemistry, KMU- Kaohsiung Medical University, Kaohsiung, 80708, Taiwan, Republic Of China
| | - Hans-Uwe Dahms
- Department of Biomedical Science and Environmental Biology, KMU- Kaohsiung Medical University, Kaohsiung, 80708, Taiwan, Republic Of China.
- Research Center for Environmental Medicine, KMU- Kaohsiung Medical University, Kaohsiung, 80708, Taiwan, Republic Of China.
- Department of Marine Biotechnology and Resources, National Sun Yat-sen University, Kaohsiung, Taiwan, Republic Of China.
| | - Santhosh Gokul Murugaiah
- Department of Marine Science, Bharathidasan University, Tiruchirappalli, Tamil Nadu, 620 024, India
| | - Muthukumar Krishnan
- Department of Marine Science, Bharathidasan University, Tiruchirappalli, Tamil Nadu, 620 024, India
| | - Arthur James Rathinam
- Department of Marine Science, Bharathidasan University, Tiruchirappalli, Tamil Nadu, 620 024, India.
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12
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Du TT, Cui T, Qiu HM, Wang NR, Huang D, Jiang XH. Simultaneous determination of tryptophan, kynurenine, kynurenic acid and two monoamines in rat plasma by HPLC-ECD/DAD. J Pharm Biomed Anal 2018; 158:8-14. [PMID: 29843007 DOI: 10.1016/j.jpba.2018.05.032] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2018] [Revised: 05/15/2018] [Accepted: 05/19/2018] [Indexed: 01/23/2023]
Abstract
A high-performance liquid chromatography method with a diode array and an electrochemical detection (HPLC-ECD/DAD) was developed to determine the levels of tryptophan (TRP), kynurenine (KYN), kynurenic acid (KYA), 5-hydroxytryptamine (5-HT) and 5-hydroxyindoleacetic acid (5-HIAA) in rat plasma. The prepared samples were separated on a BDS column (4.6 mm × 250 mm, 5 mm) with column oven temperature of 25 °C. The mobile phase consisted of 5% acetonitrile and a buffer solution, which contained 25 mmol/L sodium acetate and 0.01 mmol/L EDTA, adjusting pH to 4.5 with acetic acid, and it was pumped at a flow-rate of 1.0 mL/min. KYN and KYA were measured by a variable wavelength detector at wavelengths 360 nm and 333 nm respectively, TRP and vanillic acid (as IS) both were measured at 280 nm. Determination of 5-HT and 5-HIAA was accomplished at the electrochemical working potential of 700 mV. Total run time was 14 min. Several parameters of the developed method were validated including linearity, accuracy precision, and stability. The results showed the established method had good LOD and separation for all of the five compounds and IS in the biological matrix. The method is simple, fast, economical and accurate. The analytical method and the results could provide a reference for the clinical and scientific research of depression.
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Affiliation(s)
- Ting-Ting Du
- School of Pharmacy, Chongqing Medical University, Chongqing, 400016, China
| | - Ting Cui
- Zunyi Medical and Pharmaceutical College, Zunyi, 563006, China
| | - Hong-Mei Qiu
- School of Pharmacy, Chongqing Medical University, Chongqing, 400016, China
| | | | - Dan Huang
- School of Pharmacy, Chongqing Medical University, Chongqing, 400016, China
| | - Xin-Hui Jiang
- School of Pharmacy, Chongqing Medical University, Chongqing, 400016, China.
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13
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Abstract
Many potentially toxic electrophilic xenobiotics and some endogenous compounds are detoxified by conversion to the corresponding glutathione S-conjugate, which is metabolized to the N-acetylcysteine S-conjugate (mercapturate) and excreted. Some mercapturate pathway components, however, are toxic. Bioactivation (toxification) may occur when the glutathione S-conjugate (or mercapturate) is converted to a cysteine S-conjugate that undergoes a β-lyase reaction. If the sulfhydryl-containing fragment produced in this reaction is reactive, toxicity may ensue. Some drugs and halogenated workplace/environmental contaminants are bioactivated by this mechanism. On the other hand, cysteine S-conjugate β-lyases occur in nature as a means of generating some biologically useful sulfhydryl-containing compounds.
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14
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Jacobs KR, Castellano-Gonzalez G, Guillemin GJ, Lovejoy DB. Major Developments in the Design of Inhibitors along the Kynurenine Pathway. Curr Med Chem 2017; 24:2471-2495. [PMID: 28464785 PMCID: PMC5748880 DOI: 10.2174/0929867324666170502123114] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2016] [Revised: 03/13/2017] [Accepted: 04/18/2017] [Indexed: 12/20/2022]
Abstract
Disrupted kynurenine pathway (KP) metabolism has been implicated in the progression of neurodegenerative disease, psychiatric disorders and cancer. Modulation of enzyme activity along this pathway may therefore offer potential new therapeutic strategies for these conditions. Considering their prominent positions in the KP, the enzymes indoleamine 2,3-dioxygenase, kynurenine 3-monooxygenase and kynurenine aminotransferase, appear the most attractive targets. Already, increasing interest in this pathway has led to the identification of a number of potent and selective enzyme inhibitors with promising pre-clinical data and the elucidation of several enzyme crystal structures provides scope to rationalize the molecular mechanisms of inhibitor activity. The field seems poised to yield one or more inhibitors that should find clinical utility.
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Affiliation(s)
- Kelly R Jacobs
- Neuroinflammation Group, Department of Biomedical Research, Faculty of Medicine and Health Sciences, Macquarie University, Sydney. Australia
| | - Gloria Castellano-Gonzalez
- Neuroinflammation Group, Department of Biomedical Research, Faculty of Medicine and Health Sciences, Macquarie University, Sydney. Australia
| | - Gilles J Guillemin
- Department of Biomedical Research, Faculty of Medicine and Health Science, Macquarie University, 2 Technology Place, Sydney. Australia
| | - David B Lovejoy
- Department of Biomedical Research, Faculty of Medicine and Health Science, Macquarie University, 2 Technology Place, Sydney. Australia
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15
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Sadok I, Gamian A, Staniszewska MM. Chromatographic analysis of tryptophan metabolites. J Sep Sci 2017; 40:3020-3045. [PMID: 28590049 PMCID: PMC5575536 DOI: 10.1002/jssc.201700184] [Citation(s) in RCA: 62] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2017] [Revised: 05/15/2017] [Accepted: 05/24/2017] [Indexed: 12/14/2022]
Abstract
The kynurenine pathway generates multiple tryptophan metabolites called collectively kynurenines and leads to formation of the enzyme cofactor nicotinamide adenine dinucleotide. The first step in this pathway is tryptophan degradation, initiated by the rate-limiting enzymes indoleamine 2,3-dioxygenase, or tryptophan 2,3-dioxygenase, depending on the tissue. The balanced kynurenine metabolism, which has been a subject of multiple studies in last decades, plays an important role in several physiological and pathological conditions such as infections, autoimmunity, neurological disorders, cancer, cataracts, as well as pregnancy. Understanding the regulation of tryptophan depletion provide novel diagnostic and treatment opportunities, however it requires reliable methods for quantification of kynurenines in biological samples with complex composition (body fluids, tissues, or cells). Trace concentrations, interference of sample components, and instability of some tryptophan metabolites need to be addressed using analytical methods. The novel separation approaches and optimized extraction protocols help to overcome difficulties in analyzing kynurenines within the complex tissue material. Recent developments in chromatography coupled with mass spectrometry provide new opportunity for quantification of tryptophan and its degradation products in various biological samples. In this review, we present current accomplishments in the chromatographic methodologies proposed for detection of tryptophan metabolites and provide a guide for choosing the optimal approach.
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Affiliation(s)
- Ilona Sadok
- Laboratory of Separation and Spectroscopic Method Applications, Centre for Interdisciplinary ResearchThe John Paul II Catholic University of LublinLublinPoland
| | - Andrzej Gamian
- Laboratory of Medical MicrobiologyHirszfeld Institute of Immunology and Experimental TherapyPolish Academy of SciencesWroclawPoland
- Department of Medical BiochemistryWroclaw Medical UniversityWroclawPoland
| | - Magdalena Maria Staniszewska
- Laboratory of Separation and Spectroscopic Method Applications, Centre for Interdisciplinary ResearchThe John Paul II Catholic University of LublinLublinPoland
- Laboratory of Medical MicrobiologyHirszfeld Institute of Immunology and Experimental TherapyPolish Academy of SciencesWroclawPoland
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16
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Nadvi NA, Salam NK, Park J, Akladios FN, Kapoor V, Collyer CA, Gorrell MD, Church WB. High resolution crystal structures of human kynurenine aminotransferase-I bound to PLP cofactor, and in complex with aminooxyacetate. Protein Sci 2017; 26:727-736. [PMID: 28097769 DOI: 10.1002/pro.3119] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2016] [Revised: 01/05/2017] [Accepted: 01/09/2017] [Indexed: 11/06/2022]
Abstract
In this study, we report two high-resolution structures of the pyridoxal 5' phosphate (PLP)-dependent enzyme kynurenine aminotransferase-I (KAT-I). One is the native structure with the cofactor in the PLP form bound to Lys247 with the highest resolution yet available for KAT-I at 1.28 Å resolution, and the other with the general PLP-dependent aminotransferase inhibitor, aminooxyacetate (AOAA) covalently bound to the cofactor at 1.54 Å. Only small conformational differences are observed in the vicinity of the aldimine (oxime) linkage with which the PLP forms the Schiff base with Lys247 in the 1.28 Å resolution native structure, in comparison to other native PLP-bound structures. We also report the inhibition of KAT-1 by AOAA and aminooxy-phenylpropionic acid (AOPP), with IC50s of 13.1 and 5.7 μM, respectively. The crystal structure of the enzyme in complex with the inhibitor AOAA revealed that the cofactor is the PLP form with the external aldimine linkage. The location of this oxime with the PLP, which forms in place of the native internal aldimine linkage of PLP of the native KAT-I, is away from the position of the native internal aldimine, with the free Lys247 substantially retaining the orientation of the native structure. Tyr101, at the active site, was observed in two conformations in both structures.
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Affiliation(s)
- Naveed A Nadvi
- Group in Biomolecular Structure and Informatics, Faculty of Pharmacy, University of Sydney, Sydney, New South Wales, Australia.,Molecular Hepatology, Centenary Institute and Sydney Medical School, University of Sydney, Sydney, New South Wales, Australia
| | - Noeris K Salam
- Group in Biomolecular Structure and Informatics, Faculty of Pharmacy, University of Sydney, Sydney, New South Wales, Australia
| | - Joohong Park
- Molecular Hepatology, Centenary Institute and Sydney Medical School, University of Sydney, Sydney, New South Wales, Australia
| | - Fady N Akladios
- Group in Biomolecular Structure and Informatics, Faculty of Pharmacy, University of Sydney, Sydney, New South Wales, Australia
| | - Vimal Kapoor
- School of Medicine and Pharmacology, The University of Western Australia, Perth, Western, Australia, Australia
| | - Charles A Collyer
- School of Molecular Bioscience, University of Sydney, Sydney, New South Wales, Australia
| | - Mark D Gorrell
- Molecular Hepatology, Centenary Institute and Sydney Medical School, University of Sydney, Sydney, New South Wales, Australia
| | - William Bret Church
- Group in Biomolecular Structure and Informatics, Faculty of Pharmacy, University of Sydney, Sydney, New South Wales, Australia
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17
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Yang C, Zhang L, Han Q, Liao C, Lan J, Ding H, Zhou H, Diao X, Li J. Kynurenine aminotransferase 3/glutamine transaminase L/cysteine conjugate beta-lyase 2 is a major glutamine transaminase in the mouse kidney. Biochem Biophys Rep 2016; 8:234-241. [PMID: 28955961 PMCID: PMC5613967 DOI: 10.1016/j.bbrep.2016.09.008] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2016] [Revised: 09/19/2016] [Accepted: 09/19/2016] [Indexed: 11/22/2022] Open
Abstract
Background Kynurenine aminotransferase 3 (KAT3) catalyzes the transamination of Kynurenine to kynurenic acid, and is identical to cysteine conjugate beta-lyase 2 (CCBL2) and glutamine transaminase L (GTL). GTL was previously purified from the rat liver and considered as a liver type glutamine transaminase. However, because of the substrate overlap and high sequence similarity of KAT3 and KAT1, it was difficult to assay the specific activity of each KAT and to study the enzyme localization in animals. Methods KAT3 transcript and protein levels as well as enzyme activity in the liver and kidney were analyzed by regular reverse transcription-polymerase chain reaction (RT-PCR), real time RT-PCR, biochemical activity assays combined with a specific inhibition assay, and western blotting using a purified and a highly specific antibody, respectively. Results This study concerns the comparative biochemical characterization and localization of KAT 3 in the mouse. The results showed that KAT3 was present in both liver and kidney of the mouse, but was much more abundant in the kidney than in the liver. The mouse KAT3 is more efficient in transamination of glutamine with indo-3-pyruvate or oxaloacetate as amino group acceptor than the mouse KAT1. Conclusions Mouse KAT3 is a major glutamine transaminase in the kidney although it was named a liver type transaminase. General significance Our data highlights KAT3 as a key enzyme for studying the nephrotoxic mechanism of some xenobiotics and the formation of chemopreventive compounds in the mouse kidney. This suggests tissue localizations of KAT3/GTL/CCBL2 in other animals may be carefully checked. Mouse kynurenine aminotransferase 3 (KAT3) was specifically inhibited by methionine. Mouse KAT3 is more abundant in the kidney than in the liver. Mouse KAT3 is a major glutamine transaminase in the kidney although it was named a liver transaminase.
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Affiliation(s)
- Cihan Yang
- Key Laboratory of Tropical Biological Resources of Ministry of Education, Hainan University, Haikou, Hainan 570228, China
- Laboratory of Tropical Veterinary Medicine and Vector Biology, College of Agriculture, Hainan University, Haikou, Hainan 570228, China
| | - Lei Zhang
- Key Laboratory of Tropical Biological Resources of Ministry of Education, Hainan University, Haikou, Hainan 570228, China
- Laboratory of Tropical Veterinary Medicine and Vector Biology, College of Agriculture, Hainan University, Haikou, Hainan 570228, China
| | - Qian Han
- Key Laboratory of Tropical Biological Resources of Ministry of Education, Hainan University, Haikou, Hainan 570228, China
- Laboratory of Tropical Veterinary Medicine and Vector Biology, College of Agriculture, Hainan University, Haikou, Hainan 570228, China
- Department of Biochemistry, Virginia Tech, Blacksburg, VA 24061, USA
- Corresponding author at: Laboratory of Tropical Veterinary Medicine and Vector Biology, College of Agriculture, Hainan University, Haikou, Hainan 570228, China.
| | - Chenghong Liao
- Key Laboratory of Tropical Biological Resources of Ministry of Education, Hainan University, Haikou, Hainan 570228, China
- Laboratory of Tropical Veterinary Medicine and Vector Biology, College of Agriculture, Hainan University, Haikou, Hainan 570228, China
| | - Jianqiang Lan
- Key Laboratory of Tropical Biological Resources of Ministry of Education, Hainan University, Haikou, Hainan 570228, China
- Laboratory of Tropical Veterinary Medicine and Vector Biology, College of Agriculture, Hainan University, Haikou, Hainan 570228, China
| | - Haizhen Ding
- Department of Biochemistry, Virginia Tech, Blacksburg, VA 24061, USA
| | - Hailong Zhou
- Laboratory of Tropical Veterinary Medicine and Vector Biology, College of Agriculture, Hainan University, Haikou, Hainan 570228, China
| | - Xiaoping Diao
- Laboratory of Tropical Veterinary Medicine and Vector Biology, College of Agriculture, Hainan University, Haikou, Hainan 570228, China
| | - Jianyong Li
- Department of Biochemistry, Virginia Tech, Blacksburg, VA 24061, USA
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18
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Kynurenine Aminotransferase Isozyme Inhibitors: A Review. Int J Mol Sci 2016; 17:ijms17060946. [PMID: 27314340 PMCID: PMC4926479 DOI: 10.3390/ijms17060946] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2016] [Revised: 06/08/2016] [Accepted: 06/10/2016] [Indexed: 12/22/2022] Open
Abstract
Kynurenine aminotransferase isozymes (KATs 1–4) are members of the pyridoxal-5’-phosphate (PLP)-dependent enzyme family, which catalyse the permanent conversion of l-kynurenine (l-KYN) to kynurenic acid (KYNA), a known neuroactive agent. As KATs are found in the mammalian brain and have key roles in the kynurenine pathway, involved in different categories of central nervous system (CNS) diseases, the KATs are prominent targets in the quest to treat neurodegenerative and cognitive impairment disorders. Recent studies suggest that inhibiting these enzymes would produce effects beneficial to patients with these conditions, as abnormally high levels of KYNA are observed. KAT-1 and KAT-3 share the highest sequence similarity of the isozymes in this family, and their active site pockets are also similar. Importantly, KAT-2 has the major role of kynurenic acid production (70%) in the human brain, and it is considered therefore that suitable inhibition of this isozyme would be most effective in managing major aspects of CNS diseases. Human KAT-2 inhibitors have been developed, but the most potent of them, chosen for further investigations, did not proceed in clinical studies due to the cross toxicity caused by their irreversible interaction with PLP, the required cofactor of the KAT isozymes, and any other PLP-dependent enzymes. As a consequence of the possibility of extensive undesirable adverse effects, it is also important to pursue KAT inhibitors that reversibly inhibit KATs and to include a strategy that seeks compounds likely to achieve substantial interaction with regions of the active site other than the PLP. The main purpose of this treatise is to review the recent developments with the inhibitors of KAT isozymes. This treatise also includes analyses of their crystallographic structures in complex with this enzyme family, which provides further insight for researchers in this and related studies.
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19
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Du YL, Singh R, Alkhalaf LM, Kuatsjah E, He HY, Eltis LD, Ryan KS. A pyridoxal phosphate–dependent enzyme that oxidizes an unactivated carbon-carbon bond. Nat Chem Biol 2016; 12:194-9. [DOI: 10.1038/nchembio.2009] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2015] [Accepted: 12/02/2015] [Indexed: 11/09/2022]
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20
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Astrocytes as Pharmacological Targets in the Treatment of Schizophrenia. HANDBOOK OF BEHAVIORAL NEUROSCIENCE 2016. [DOI: 10.1016/b978-0-12-800981-9.00025-0] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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21
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Dounay AB, Tuttle JB, Verhoest PR. Challenges and Opportunities in the Discovery of New Therapeutics Targeting the Kynurenine Pathway. J Med Chem 2015. [DOI: 10.1021/acs.jmedchem.5b00461] [Citation(s) in RCA: 90] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Affiliation(s)
- Amy B. Dounay
- Department
of Chemistry and Biochemistry, Colorado College, 14 E. Cache
La Poudre Street, Colorado Springs, Colorado 80903, United States
| | - Jamison B. Tuttle
- Worldwide Medicinal Chemistry, Pfizer Worldwide Research & Development, Cambridge, Massachusetts 02139, United States
| | - Patrick R. Verhoest
- Worldwide Medicinal Chemistry, Pfizer Worldwide Research & Development, Cambridge, Massachusetts 02139, United States
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22
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Xu Y, Zheng Q, Yu L, Zhang H, Sun C. A molecular dynamics and computational study of human KAT3 involved in KYN pathway. Sci China Chem 2012. [DOI: 10.1007/s11426-012-4802-8] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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23
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Yoshihara S, Otani H, Tsunoda M, Ishii K, Iizuka H, Ichiba H, Fukushima T. Alterations in extracellular tryptophan and dopamine concentrations in rat striatum following peripheral administration of d- and l-tryptophan: An in vivo microdialysis study. Neurosci Lett 2012; 526:74-8. [DOI: 10.1016/j.neulet.2012.07.046] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2012] [Revised: 07/19/2012] [Accepted: 07/23/2012] [Indexed: 10/28/2022]
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24
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Okada K, Angkawidjaja C, Koga Y, Takano K, Kanaya S. Characteristic features of kynurenine aminotransferase allosterically regulated by (alpha)-ketoglutarate in cooperation with kynurenine. PLoS One 2012; 7:e40307. [PMID: 22792273 PMCID: PMC3391261 DOI: 10.1371/journal.pone.0040307] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2011] [Accepted: 06/05/2012] [Indexed: 12/05/2022] Open
Abstract
Kynurenine aminotransferase from Pyrococcus horikoshii OT3 (PhKAT), which is a homodimeric protein, catalyzes the conversion of kynurenine (KYN) to kynurenic acid (KYNA). We analyzed the transaminase reaction mechanisms of this protein with pyridoxal-5′-phosphate (PLP), KYN and α-ketoglutaric acid (2OG) or oxaloacetic acid (OXA). 2OG significantly inhibited KAT activities in kinetic analyses, suggesting that a KYNA biosynthesis is allosterically regulated by 2OG. Its inhibitions evidently were unlocked by KYN. 2OG and KYN functioned as an inhibitor and activator in response to changes in the concentrations of KYN and 2OG, respectively. The affinities of one subunit for PLP or 2OG were different from that of the other subunit, as confirmed by spectrophotometry and isothermal titration calorimetry, suggesting that the difference of affinities between subunits might play a role in regulations of the KAT reaction. Moreover, we identified two active and allosteric sites in the crystal structure of PhKAT-2OG complexes. The crystal structure of PhKAT in complex with four 2OGs demonstrates that two 2OGs in allosteric sites are effector molecules which inhibit the KYNA productions. Thus, the combined data lead to the conclusion that PhKAT probably is regulated by allosteric control machineries, with 2OG as the allosteric inhibitor.
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Affiliation(s)
- Ken Okada
- Department of Material and Life Science, Graduate School of Engineering, Osaka University, Osaka, Japan.
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25
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Biochemical and structural characterization of mouse mitochondrial aspartate aminotransferase, a newly identified kynurenine aminotransferase-IV. Biosci Rep 2012; 31:323-32. [PMID: 20977429 DOI: 10.1042/bsr20100117] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
Mammalian mAspAT (mitochondrial aspartate aminotransferase) is recently reported to have KAT (kynurenine aminotransferase) activity and plays a role in the biosynthesis of KYNA (kynurenic acid) in rat, mouse and human brains. This study concerns the biochemical and structural characterization of mouse mAspAT. In this study, mouse mAspAT cDNA was amplified from mouse brain first stand cDNA and its recombinant protein was expressed in an Escherichia coli expression system. Sixteen oxo acids were tested for the co-substrate specificity of mouse mAspAT and 14 of them were shown to be capable of serving as co-substrates for the enzyme. Structural analysis of mAspAT by macromolecular crystallography revealed that the cofactor-binding residues of mAspAT are similar to those of other KATs. The substrate-binding residues of mAspAT are slightly different from those of other KATs. Our results provide a biochemical and structural basis towards understanding the overall physiological role of mAspAT in vivo and insight into controlling the levels of endogenous KYNA through modulation of the enzyme in the mouse brain.
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26
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Design and synthesis of novel inhibitors of human kynurenine aminotransferase-I. Bioorg Med Chem Lett 2012; 22:1579-81. [DOI: 10.1016/j.bmcl.2011.12.138] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2011] [Revised: 12/28/2011] [Accepted: 12/29/2011] [Indexed: 11/23/2022]
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27
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Bridges CC, Krasnikov BF, Joshee L, Pinto JT, Hallen A, Li J, Zalups RK, Cooper AJL. New insights into the metabolism of organomercury compounds: mercury-containing cysteine S-conjugates are substrates of human glutamine transaminase K and potent inactivators of cystathionine γ-lyase. Arch Biochem Biophys 2011; 517:20-9. [PMID: 22093698 DOI: 10.1016/j.abb.2011.11.002] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2011] [Revised: 10/31/2011] [Accepted: 11/01/2011] [Indexed: 11/26/2022]
Abstract
Anthropogenic practices and recycling in the environment through natural processes result in release of potentially harmful levels of mercury into the biosphere. Mercury, especially organic forms, accumulates in the food chain. Mercury reacts readily with sulfur-containing compounds and often exists as a thiol S-conjugate, such as the l-cysteine (Cys)-S-conjugate of methylmercury (CH(3)Hg-S-Cys) or inorganic mercury (Cys-S-Hg-S-Cys). These S-conjugates are structurally similar to l-methionine and l-cystine/l-cystathionine, respectively. Bovine and rat glutamine transaminase K (GTK) catalyze transamination of sulfur-containing amino acids. Recombinant human GTK (rhGTK) has a relatively open catalytic active site, and we report here that this enzyme, like the rat and bovine enzymes, can also utilize sulfur-containing l-amino acids, including l-methionine, l-cystine, and l-cystathionine as substrates. The current study extends this list to include mercuric S-conjugates, and shows that CH(3)Hg-S-Cys and Cys-S-Hg-S-Cys are substrates and reversible inhibitors of rhGTK. The homocysteine S-conjugates, Hcy-S-Hg-S-Hcy and CH(3)Hg-S-Hcy, are also inhibitors. Finally, we show that HgCl(2), CH(3)Hg-S-Cys and Cys-S-Hg-S-Cys are potent irreversible inhibitors of rat cystathionine γ-lyase. The present study broadens our knowledge of the biochemistry of mercury compounds by showing that Cys S-conjugates of mercury interact with enzymes that catalyze transformations of biologically important sulfur-containing amino acids.
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Affiliation(s)
- Christy C Bridges
- Division of Basic Medical Sciences, Mercer University School of Medicine, Macon, GA 31207, USA
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Ishii K, Iizuka H, Ogaya T, Song Z, Fukushima T. Comparative study on kynurenic acid production in the rat striatum by tryptophan enantiomers: An in vivo microdialysis study. Chirality 2011; 23 Suppl 1:E12-5. [DOI: 10.1002/chir.20938] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2010] [Accepted: 11/29/2010] [Indexed: 11/11/2022]
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29
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Tyrosine aminotransferase: biochemical and structural properties and molecular dynamics simulations. Protein Cell 2010; 1:1023-32. [PMID: 21153519 DOI: 10.1007/s13238-010-0128-5] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2010] [Accepted: 10/19/2010] [Indexed: 10/18/2022] Open
Abstract
Tyrosine aminotransferase (TAT) catalyzes the transamination of tyrosine and other aromatic amino acids. The enzyme is thought to play a role in tyrosinemia type II, hepatitis and hepatic carcinoma recovery. The objective of this study is to investigate its biochemical and structural characteristics and substrate specificity in order to provide insight regarding its involvement in these diseases. Mouse TAT (mTAT) was cloned from a mouse cDNA library, and its recombinant protein was produced using Escherichia coli cells and purified using various chromatographic techniques. The recombinant mTAT is able to catalyze the transamination of tyrosine using α-ketoglutaric acid as an amino group acceptor at neutral pH. The enzyme also can use glutamate and phenylalanine as amino group donors and p-hydroxy-phenylpyruvate, phenylpyruvate and alpha-ketocaproic acid as amino group acceptors. Through macromolecular crystallography we have determined the mTAT crystal structure at 2.9 Å resolution. The crystal structure revealed the interaction between the pyridoxal-5'-phosphate cofactor and the enzyme, as well as the formation of a disulphide bond. The detection of disulphide bond provides some rational explanation regarding previously observed TAT inactivation under oxidative conditions and reactivation of the inactive TAT in the presence of a reducing agent. Molecular dynamics simulations using the crystal structures of Trypanosoma cruzi TAT and human TAT provided further insight regarding the substrate-enzyme interactions and substrate specificity. The biochemical and structural properties of TAT and the binding of its cofactor and the substrate may help in elucidation of the mechanism of TAT inhibition and activation.
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Wong J, Ray WJ, Kornilova AY. Development of a microplate fluorescence assay for kynurenine aminotransferase. Anal Biochem 2010; 409:183-8. [PMID: 21059337 DOI: 10.1016/j.ab.2010.10.037] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2010] [Revised: 10/29/2010] [Accepted: 10/29/2010] [Indexed: 11/27/2022]
Abstract
Inhibition of kynurenine aminotransferases (KATs) is a strategy to therapeutically reduce levels of kynurenic acid (KYNA), an endogenous antagonist of glutamatergic N-methyl-D-aspartate (NMDA) and cholinergic α₇ nicotinic receptors. Several methods of measuring KAT activity in vitro have been developed, but none is well-suited to high throughput and automation. In this article, we describe a modification of existing high-performance liquid chromatography (HPLC)-based methods that enables the development of a 96-well microplate assay in both enzyme- and cell-based formats using human KAT I as an example. KYNA enzymatically produced from L-kynurenine is measured directly in a reaction mixture fluorimetrically.
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Affiliation(s)
- Jacky Wong
- Neurology Department, Merck, West Point, PA 19486, USA
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31
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Rossi F, Valentina C, Garavaglia S, Sathyasaikumar KV, Schwarcz R, Kojima SI, Okuwaki K, Ono SI, Kajii Y, Rizzi M. Crystal structure-based selective targeting of the pyridoxal 5'-phosphate dependent enzyme kynurenine aminotransferase II for cognitive enhancement. J Med Chem 2010; 53:5684-9. [PMID: 20684605 DOI: 10.1021/jm100464k] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Fluctuations in the brain levels of the neuromodulator kynurenic acid may control cognitive processes and play a causative role in several catastrophic brain diseases. Elimination of the pyridoxal 5'-phosphate dependent enzyme kynurenine aminotransferase II reduces cerebral kynurenic acid synthesis and has procognitive effects. The present description of the crystal structure of human kynurenine aminotransferase II in complex with its potent and specific primary amine-bearing fluoroquinolone inhibitor (S)-(-)-9-(4-aminopiperazin-1-yl)-8-fluoro-3-methyl-6-oxo-2,3-dihydro-6H-1-oxa-3a-azaphenalene-5-carboxylic acid (BFF-122) should facilitate the structure-based development of cognition-enhancing drugs. From a medicinal chemistry perspective our results demonstrate that the issue of inhibitor specificity for highly conserved PLP-dependent enzymes could be successfully addressed.
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Affiliation(s)
- Franca Rossi
- University of Piemonte Orientale Amedeo Avogadro, Novara, Italy
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32
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Han Q, Cai T, Tagle DA, Li J. Thermal stability, pH dependence and inhibition of four murine kynurenine aminotransferases. BMC BIOCHEMISTRY 2010; 11:19. [PMID: 20482848 PMCID: PMC2890522 DOI: 10.1186/1471-2091-11-19] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/05/2010] [Accepted: 05/19/2010] [Indexed: 11/10/2022]
Abstract
BACKGROUND Kynurenine aminotransferase (KAT) catalyzes the transamination of kynunrenine to kynurenic acid (KYNA). KYNA is a neuroactive compound and functions as an antagonist of alpha7-nicotinic acetylcholine receptors and is the only known endogenous antagonist of N-methyl-D-aspartate receptors. Four KAT enzymes, KAT I/glutamine transaminase K/cysteine conjugate beta-lyase 1, KAT II/aminoadipate aminotransferase, KAT III/cysteine conjugate beta-lyase 2, and KAT IV/glutamic-oxaloacetic transaminase 2/mitochondrial aspartate aminotransferase, have been reported in mammalian brains. Because of the substrate overlap of the four KAT enzymes, it is difficult to assay the specific activity of each KAT in animal brains. RESULTS This study concerns the functional expression and comparative characterization of KAT I, II, III, and IV from mice. At the applied test conditions, equimolar tryptophan with kynurenine significantly inhibited only mouse KAT I and IV, equimolar methionine inhibited only mouse KAT III and equimolar aspartate inhibited only mouse KAT IV. The activity of mouse KAT II was not significantly inhibited by any proteinogenic amino acids at equimolar concentrations. pH optima, temperature preferences of four KATs were also tested in this study. Midpoint temperatures of the protein melting, half life values at 65 degrees C, and pKa values of mouse KAT I, II, III, and IV were 69.8, 65.9, 64.8 and 66.5 degrees C; 69.7, 27.4, 3.9 and 6.5 min; pH 7.6, 5.7, 8.7 and 6.9, respectively. CONCLUSION The characteristics reported here could be used to develop specific assay methods for each of the four murine KATs. These specific assays could be used to identify which KAT is affected in mouse models for research and to develop small molecule drugs for prevention and treatment of KAT-involved human diseases.
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Affiliation(s)
- Qian Han
- Department of Biochemistry, Virginia Tech, Blacksburg, 24061, USA
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33
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Ishii K, Ogaya T, Song Z, Iizuka H, Fukushima T. Changes in the plasma concentrations of D-kynurenine and kynurenic acid in rats after intraperitoneal administration of tryptophan enantiomers. Chirality 2010; 22:901-6. [DOI: 10.1002/chir.20850] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Cysteine S-conjugate β-lyases: important roles in the metabolism of naturally occurring sulfur and selenium-containing compounds, xenobiotics and anticancer agents. Amino Acids 2010; 41:7-27. [PMID: 20306345 DOI: 10.1007/s00726-010-0552-0] [Citation(s) in RCA: 74] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2010] [Accepted: 03/01/2010] [Indexed: 12/13/2022]
Abstract
Cysteine S-conjugate β-lyases are pyridoxal 5'-phosphate-containing enzymes that catalyze β-elimination reactions with cysteine S-conjugates that possess a good leaving group in the β-position. The end products are aminoacrylate and a sulfur-containing fragment. The aminoacrylate tautomerizes and hydrolyzes to pyruvate and ammonia. The mammalian cysteine S-conjugate β-lyases thus far identified are enzymes involved in amino acid metabolism that catalyze β-lyase reactions as non-physiological side reactions. Most are aminotransferases. In some cases the lyase is inactivated by reaction products. The cysteine S-conjugate β-lyases are of much interest to toxicologists because they play an important key role in the bioactivation (toxication) of halogenated alkenes, some of which are produced on an industrial scale and are environmental contaminants. The cysteine S-conjugate β-lyases have been reviewed in this journal previously (Cooper and Pinto in Amino Acids 30:1-15, 2006). Here, we focus on more recent findings regarding: (1) the identification of enzymes associated with high-M(r) cysteine S-conjugate β-lyases in the cytosolic and mitochondrial fractions of rat liver and kidney; (2) the mechanism of syncatalytic inactivation of rat liver mitochondrial aspartate aminotransferase by the nephrotoxic β-lyase substrate S-(1,1,2,2-tetrafluoroethyl)-L-cysteine (the cysteine S-conjugate of tetrafluoroethylene); (3) toxicant channeling of reactive fragments from the active site of mitochondrial aspartate aminotransferase to susceptible proteins in the mitochondria; (4) the involvement of cysteine S-conjugate β-lyases in the metabolism/bioactivation of drugs and natural products; and (5) the role of cysteine S-conjugate β-lyases in the metabolism of selenocysteine Se-conjugates. This review emphasizes the fact that the cysteine S-conjugate β-lyases are biologically more important than hitherto appreciated.
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Han Q, Cai T, Tagle DA, Li J. Structure, expression, and function of kynurenine aminotransferases in human and rodent brains. Cell Mol Life Sci 2010; 67:353-68. [PMID: 19826765 PMCID: PMC2867614 DOI: 10.1007/s00018-009-0166-4] [Citation(s) in RCA: 170] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2009] [Revised: 09/27/2009] [Accepted: 09/29/2009] [Indexed: 01/12/2023]
Abstract
Kynurenine aminotransferases (KATs) catalyze the synthesis of kynurenic acid (KYNA), an endogenous antagonist of N-methyl-D: -aspartate and alpha 7-nicotinic acetylcholine receptors. Abnormal KYNA levels in human brains are implicated in the pathophysiology of schizophrenia, Alzheimer's disease, and other neurological disorders. Four KATs have been reported in mammalian brains, KAT I/glutamine transaminase K/cysteine conjugate beta-lyase 1, KAT II/aminoadipate aminotransferase, KAT III/cysteine conjugate beta-lyase 2, and KAT IV/glutamic-oxaloacetic transaminase 2/mitochondrial aspartate aminotransferase. KAT II has a striking tertiary structure in N-terminal part and forms a new subgroup in fold type I aminotransferases, which has been classified as subgroup Iepsilon. Knowledge regarding KATs is vast and complex; therefore, this review is focused on recent important progress of their gene characterization, physiological and biochemical function, and structural properties. The biochemical differences of four KATs, specific enzyme activity assays, and the structural insights into the mechanism of catalysis and inhibition of these enzymes are discussed.
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Affiliation(s)
- Qian Han
- Department of Biochemistry, Virginia Tech, Blacksburg, VA 24061 USA
| | - Tao Cai
- OIIB, NIDCR, National Institutes of Health, Bethesda MD, 20892-4322 USA
| | - Danilo A. Tagle
- Neuroscience Center, NINDS, National Institutes of Health, Bethesda, MD 2089-29525 USA
| | - Jianyong Li
- Department of Biochemistry, Virginia Tech, Blacksburg, VA 24061 USA
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Abstract
Many potentially toxic electrophiles react with glutathione to form glutathione S-conjugates in reactions catalyzed or enhanced by glutathione S-transferases. The glutathione S-conjugate is sequentially converted to the cysteinylglycine-, cysteine- and N-acetyl-cysteine S-conjugate (mercapturate). The mercapturate is generally more polar and water soluble than the parent electrophile and is readily excreted. Excretion of the mercapturate represents a detoxication mechanism. Some endogenous compounds, such as leukotrienes, prostaglandin (PG) A2, 15-deoxy-Δ12,14-PGJ2, and hydroxynonenal can also be metabolized to mercapturates and excreted. On occasion, however, formation of glutathione S- and cysteine S-conjugates are bioactivation events as the metabolites are mutagenic and/or cytotoxic. When the cysteine S-conjugate contains a strong electron-withdrawing group attached at the sulfur, it may be converted by cysteine S-conjugate β-lyases to pyruvate, ammonium and the original electrophile modified to contain an –SH group. If this modified electrophile is highly reactive then the enzymes of the mercapturate pathway together with the cysteine S-conjugate β-lyases constitute a bioactivation pathway. Some endogenous halogenated environmental contaminants and drugs are bioactivated by this mechanism. Recent studies suggest that coupling of enzymes of the mercapturate pathway to cysteine S-conjugate β-lyases may be more common in nature and more widespread in the metabolism of electrophilic xenobiotics than previously realized.
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37
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Quantum mechanics/molecular mechanics (QM/MM) modeling of the irreversible transamination of l-kynurenine to kynurenic acid: The round dance of kynurenine aminotransferase II. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2009; 1794:1802-12. [DOI: 10.1016/j.bbapap.2009.08.016] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/18/2009] [Revised: 08/12/2009] [Accepted: 08/18/2009] [Indexed: 11/21/2022]
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38
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Changes in Extracellular Kynurenic Acid Concentrations in Rat Prefrontal Cortex After d-Kynurenine Infusion: An In vivo Microdialysis Study. Neurochem Res 2009; 35:559-63. [DOI: 10.1007/s11064-009-0099-1] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/11/2009] [Indexed: 11/25/2022]
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39
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Lee JI, Nian H, Cooper AJL, Sinha R, Dai J, Bisson WH, Dashwood RH, Pinto JT. Alpha-keto acid metabolites of naturally occurring organoselenium compounds as inhibitors of histone deacetylase in human prostate cancer cells. Cancer Prev Res (Phila) 2009; 2:683-93. [PMID: 19584079 PMCID: PMC2902275 DOI: 10.1158/1940-6207.capr-09-0047] [Citation(s) in RCA: 71] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Histone deacetylase (HDAC) inhibitors are gaining interest as cancer therapeutic agents. We tested the hypothesis that natural organoselenium compounds might be metabolized to HDAC inhibitors in human prostate cancer cells. Se-Methyl-L-selenocysteine (MSC) and selenomethionine are amino acid components of selenium-enriched yeast. In a cell-free system, glutamine transaminase K (GTK) and L-amino acid oxidase convert MSC to the corresponding alpha-keto acid, beta-methylselenopyruvate (MSP), and L-amino acid oxidase converts selenomethionine to its corresponding alpha-keto acid, alpha-keto-gamma-methylselenobutyrate (KMSB). Although methionine (sulfur analogue of selenomethionine) is an excellent substrate for GTK, selenomethionine is poorly metabolized. Structurally, MSP and KMSB resemble the known HDAC inhibitor butyrate. We examined androgen-responsive LNCaP cells and androgen-independent LNCaP C4-2, PC-3, and DU145 cells and found that these human prostate cancer cells exhibit endogenous GTK activities. In the corresponding cytosolic extracts, the metabolism of MSC was accompanied by the concomitant formation of MSP. In MSP-treated and KMSB-treated prostate cancer cell lines, acetylated histone 3 levels increased within 5 hours, and returned to essentially baseline levels by 24 hours, suggesting a rapid, transient induction of histone acetylation. In an in vitro HDAC activity assay, the selenoamino acids, MSC and selenomethionine, had no effect at concentrations up to 2.5 mmol/L, whereas MSP and KMSB both inhibited HDAC activity. We conclude that, in addition to targeting redox-sensitive signaling proteins and transcription factors, alpha-keto acid metabolites of MSC and selenomethionine can alter HDAC activity and histone acetylation status. These findings provide a potential new paradigm by which naturally occurring organoselenium might prevent the progression of human prostate cancer.
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Affiliation(s)
- Jeong-In Lee
- Department of Biochemistry and Molecular Biology, New York Medical College, Valhalla, NY 10595, USA
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40
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Han Q, Robinson H, Cai T, Tagle DA, Li J. Structural insight into the inhibition of human kynurenine aminotransferase I/glutamine transaminase K. J Med Chem 2009; 52:2786-93. [PMID: 19338303 DOI: 10.1021/jm9000874] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Human kynurenine aminotransferase I (hKAT I) catalyzes the formation of kynurenic acid, a neuroactive compound. Here, we report three high-resolution crystal structures (1.50-1.55 A) of hKAT I that are in complex with glycerol and each of two inhibitors of hKAT I: indole-3-acetic acid (IAC) and Tris. Because Tris is able to occupy the substrate binding position, we speculate that this may be the basis for hKAT I inhibition. Furthermore, the hKAT/IAC complex structure reveals that the binding moieties of the inhibitor are its indole ring and a carboxyl group. Six chemicals with both binding moieties were tested for their ability to inhibit hKAT I activity; 3-indolepropionic acid and DL-indole-3-lactic acid demonstrated the highest level of inhibition, and as they cannot be considered as substrates of the enzyme, these two inhibitors are promising candidates for future study. Perhaps even more significantly, we report the discovery of two different ligands located simultaneously in the hKAT I active center for the first time.
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Affiliation(s)
- Qian Han
- Department of Biochemistry, Virginia Tech, Blacksburg, Virginia 24061, USA.
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41
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Fukushima T, Sone Y, Mitsuhashi S, Tomiya M, Toyo'oka T. Alteration of kynurenic acid concentration in rat plasma following optically pure kynurenine administration: A comparative study between enantiomers. Chirality 2009; 21:468-72. [DOI: 10.1002/chir.20620] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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42
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Substrate specificity and structure of human aminoadipate aminotransferase/kynurenine aminotransferase II. Biosci Rep 2008; 28:205-15. [PMID: 18620547 DOI: 10.1042/bsr20080085] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
KAT (kynurenine aminotransferase) II is a primary enzyme in the brain for catalysing the transamination of kynurenine to KYNA (kynurenic acid). KYNA is the only known endogenous antagonist of the N-methyl-D-aspartate receptor. The enzyme also catalyses the transamination of aminoadipate to alpha-oxoadipate; therefore it was initially named AADAT (aminoadipate aminotransferase). As an endotoxin, aminoadipate influences various elements of glutamatergic neurotransmission and kills primary astrocytes in the brain. A number of studies dealing with the biochemical and functional characteristics of this enzyme exist in the literature, but a systematic assessment of KAT II addressing its substrate profile and kinetic properties has not been performed. The present study examines the biochemical and structural characterization of a human KAT II/AADAT. Substrate screening of human KAT II revealed that the enzyme has a very broad substrate specificity, is capable of catalysing the transamination of 16 out of 24 tested amino acids and could utilize all 16 tested alpha-oxo acids as amino-group acceptors. Kinetic analysis of human KAT II demonstrated its catalytic efficiency for individual amino-group donors and acceptors, providing information as to its preferred substrate affinity. Structural analysis of the human KAT II complex with alpha-oxoglutaric acid revealed a conformational change of an N-terminal fraction, residues 15-33, that is able to adapt to different substrate sizes, which provides a structural basis for its broad substrate specificity.
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43
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Biochemical and structural properties of mouse kynurenine aminotransferase III. Mol Cell Biol 2008; 29:784-93. [PMID: 19029248 DOI: 10.1128/mcb.01272-08] [Citation(s) in RCA: 65] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
Kynurenine aminotransferase III (KAT III) has been considered to be involved in the production of mammalian brain kynurenic acid (KYNA), which plays an important role in protecting neurons from overstimulation by excitatory neurotransmitters. The enzyme was identified based on its high sequence identity with mammalian KAT I, but its activity toward kynurenine and its structural characteristics have not been established. In this study, the biochemical and structural properties of mouse KAT III (mKAT III) were determined. Specifically, mKAT III cDNA was amplified from a mouse brain cDNA library, and its recombinant protein was expressed in an insect cell protein expression system. We established that mKAT III is able to efficiently catalyze the transamination of kynurenine to KYNA and has optimum activity at relatively basic conditions of around pH 9.0 and at relatively high temperatures of 50 to 60 degrees C. In addition, mKAT III is active toward a number of other amino acids. Its activity toward kynurenine is significantly decreased in the presence of methionine, histidine, glutamine, leucine, cysteine, and 3-hydroxykynurenine. Through macromolecular crystallography, we determined the mKAT III crystal structure and its structures in complex with kynurenine and glutamine. Structural analysis revealed the overall architecture of mKAT III and its cofactor binding site and active center residues. This is the first report concerning the biochemical characteristics and crystal structures of KAT III enzymes and provides a basis toward understanding the overall physiological role of mammalian KAT III in vivo and insight into regulating the levels of endogenous KYNA through modulation of the enzyme in the mouse brain.
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Curiosity to kill the KAT (kynurenine aminotransferase): structural insights into brain kynurenic acid synthesis. Curr Opin Struct Biol 2008; 18:748-55. [PMID: 18950711 DOI: 10.1016/j.sbi.2008.09.009] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2008] [Revised: 09/22/2008] [Accepted: 09/24/2008] [Indexed: 11/23/2022]
Abstract
Kynurenine aminotransferases are pyridoxal-5'-phosphate-dependent enzymes, which catalyze the synthesis of kynurenic acid, a highly neuroactive metabolite whose impairment is associated with a number of severe brain disorders. Crystallographic studies of these enzymes from different organisms, including humans, have revealed distinctive structural traits of type I and type II kynurenine aminotransferases. A striking difference concerns domain swapping of the N-terminal regions, which play equivalent key functional roles in both an unswapped and swapped structure in type I and type II isozymes. Different conformational changes during catalysis create divergent active sites in the two isozymes and affect substrate specificity. Structural investigations indicate intriguing evolutionary relationships and pave the way for the design of isozyme-specific inhibitors, which are of interest for the treatment of catastrophic brain diseases such as Alzheimer's disease and schizophrenia.
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45
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Cooper AJL, Pinto JT, Krasnikov BF, Niatsetskaya ZV, Han Q, Li J, Vauzour D, Spencer JPE. Substrate specificity of human glutamine transaminase K as an aminotransferase and as a cysteine S-conjugate beta-lyase. Arch Biochem Biophys 2008; 474:72-81. [PMID: 18342615 PMCID: PMC2474740 DOI: 10.1016/j.abb.2008.02.038] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2007] [Revised: 02/14/2008] [Accepted: 02/24/2008] [Indexed: 11/16/2022]
Abstract
Rat kidney glutamine transaminase K (GTK) exhibits broad specificity both as an aminotransferase and as a cysteine S-conjugate beta-lyase. The beta-lyase reaction products are pyruvate, ammonium and a sulfhydryl-containing fragment. We show here that recombinant human GTK (rhGTK) also exhibits broad specificity both as an aminotransferase and as a cysteine S-conjugate beta-lyase. S-(1,1,2,2-Tetrafluoroethyl)-l-cysteine is an excellent aminotransferase and beta-lyase substrate of rhGTK. Moderate aminotransferase and beta-lyase activities occur with the chemopreventive agent Se-methyl-l-selenocysteine. l-3-(2-Naphthyl)alanine, l-3-(1-naphthyl)alanine, 5-S-l-cysteinyldopamine and 5-S-l-cysteinyl-l-DOPA are measurable aminotransferase substrates, indicating that the active site can accommodate large aromatic amino acids. The alpha-keto acids generated by transamination/l-amino acid oxidase activity of the two catechol cysteine S-conjugates are unstable. A slow rhGTK-catalyzed beta-elimination reaction, as measured by pyruvate formation, was demonstrated with 5-S-l-cysteinyldopamine, but not with 5-S-l-cysteinyl-l-DOPA. The importance of transamination, oxidation and beta-elimination reactions involving 5-S-l-cysteinyldopamine, 5-S-l-cysteinyl-l-DOPA and Se-methyl-l-selenocysteine in human tissues and their biological relevance are discussed.
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Affiliation(s)
- Arthur J L Cooper
- Department of Biochemistry and Molecular Biology, New York Medical College, Valhalla, NY, USA.
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46
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Crystal Structure of MJ0684 from Methanococcus jannaschii, a Novel Archaeal Homolog of Kynurenine Aminotransferase. B KOREAN CHEM SOC 2008. [DOI: 10.5012/bkcs.2008.29.1.173] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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47
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Wogulis M, Chew ER, Donohoue PD, Wilson DK. Identification of formyl kynurenine formamidase and kynurenine aminotransferase from Saccharomyces cerevisiae using crystallographic, bioinformatic and biochemical evidence. Biochemistry 2008; 47:1608-21. [PMID: 18205391 DOI: 10.1021/bi701172v] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The essential enzymatic cofactor NAD+ can be synthesized in many eukaryotes, including Saccharomyces cerevisiae and mammals, using tryptophan as a starting material. Metabolites along the pathway or on branches have important biological functions. For example, kynurenic acid can act as an NMDA antagonist, thereby functioning as a neuroprotectant in a wide range of pathological states. N-Formyl kynurenine formamidase (FKF) catalyzes the second step of the NAD+ biosynthetic pathway by hydrolyzing N-formyl kynurenine to produce kynurenine and formate. The S. cerevisiae FKF had been reported to be a pyridoxal phosphate-dependent enzyme encoded by BNA3. We used combined crystallographic, bioinformatic and biochemical methods to demonstrate that Bna3p is not an FKF but rather is most likely the yeast kynurenine aminotransferase, which converts kynurenine to kynurenic acid. Additionally, we identify YDR428C, a yeast ORF coding for an alpha/beta hydrolase with no previously assigned function, as the FKF. We predicted its function based on our interpretation of prior structural genomics results and on its sequence homology to known FKFs. Biochemical, bioinformatics, genetic and in vivo metabolite data derived from LC-MS demonstrate that YDR428C, which we have designated BNA7, is the yeast FKF.
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Affiliation(s)
- Mark Wogulis
- Section of Molecular and Cellular Biology, University of California, Davis, California 95616, USA
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Han Q, Gao YG, Robinson H, Li J. Structural insight into the mechanism of substrate specificity of aedes kynurenine aminotransferase. Biochemistry 2008; 47:1622-30. [PMID: 18186649 DOI: 10.1021/bi701800j] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Aedes aegypti kynurenine aminotransferase (AeKAT) is a multifunctional aminotransferase. It catalyzes the transamination of a number of amino acids and uses many biologically relevant alpha-keto acids as amino group acceptors. AeKAT also is a cysteine S-conjugate beta-lyase. The most important function of AeKAT is the biosynthesis of kynurenic acid, a natural antagonist of NMDA and alpha7-nicotinic acetylcholine receptors. Here, we report the crystal structures of AeKAT in complex with its best amino acid substrates, glutamine and cysteine. Glutamine is found in both subunits of the biological dimer, and cysteine is found in one of the two subunits. Both substrates form external aldemines with pyridoxal 5-phosphate in the structures. This is the first instance in which one pyridoxal 5-phosphate enzyme has been crystallized with cysteine or glutamine forming external aldimine complexes, cysteinyl aldimine and glutaminyl aldimine. All the units with substrate are in the closed conformation form, and the unit without substrate is in the open form, which suggests that the binding of substrate induces the conformation change of AeKAT. By comparing the active site residues of the AeKAT-cysteine structure with those of the human KAT I-phenylalanine structure, we determined that Tyr286 in AeKAT is changed to Phe278 in human KAT I, which may explain why AeKAT transaminates hydrophilic amino acids more efficiently than human KAT I does.
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Affiliation(s)
- Qian Han
- Department of Biochemistry, Virginia Tech, Blacksburg, Virginia 24061, USA
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Han Q, Robinson H, Li J. Crystal structure of human kynurenine aminotransferase II. J Biol Chem 2007; 283:3567-3573. [PMID: 18056995 DOI: 10.1074/jbc.m708358200] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
Human kynurenine aminotransferase II (hKAT-II) efficiently catalyzes the transamination of knunrenine to kynurenic acid (KYNA). KYNA is the only known endogenous antagonist of N-methyl-D-aspartate (NMDA) receptors and is also an antagonist of 7-nicotinic acetylcholine receptors. Abnormal concentrations of brain KYNA have been implicated in the pathogenesis and development of several neurological and psychiatric diseases in humans. Consequently, enzymes involved in the production of brain KYNA have been considered potential regulatory targets. In this article, we report a 2.16 A crystal structure of hKAT-II and a 1.95 A structure of its complex with kynurenine. The protein architecture of hKAT-II reveals that it belongs to the fold-type I pyridoxal 5-phosphate (PLP)-dependent enzymes. In comparison with all subclasses of fold-type I-PLP-dependent enzymes, we propose that hKAT-II represents a novel subclass in the fold-type I enzymes because of the unique folding of its first 65 N-terminal residues. This study provides a molecular basis for future effort in maintaining physiological concentrations of KYNA through molecular and biochemical regulation of hKAT-II.
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Affiliation(s)
- Qian Han
- Department of Biochemistry, Virginia Tech University, Blacksburg, Virginia 24061
| | - Howard Robinson
- Biology Department, Brookhaven National Laboratory, Upton, New York 11973
| | - Jianyong Li
- Department of Biochemistry, Virginia Tech University, Blacksburg, Virginia 24061.
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Rossi F, Garavaglia S, Montalbano V, Walsh MA, Rizzi M. Crystal structure of human kynurenine aminotransferase II, a drug target for the treatment of schizophrenia. J Biol Chem 2007; 283:3559-3566. [PMID: 18056996 DOI: 10.1074/jbc.m707925200] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Kynurenic acid is an endogenous neuroactive compound whose unbalancing is involved in the pathogenesis and progression of several neurological diseases. Kynurenic acid synthesis in the human brain is sustained by the catalytic activity of two kynurenine aminotransferases, hKAT I and hKAT II. A wealth of pharmacological data highlight hKAT II as a sensible target for the treatment of neuropathological conditions characterized by a kynurenic acid excess, such as schizophrenia and cognitive impairment. We have solved the structure of human KAT II by means of the single-wavelength anomalous dispersion method at 2.3-A resolution. Although closely resembling the classical aminotransferase fold, the hKAT II architecture displays unique features. Structural comparison with a prototypical aspartate aminotransferase reveals a novel antiparallel strand-loop-strand motif that forms an unprecedented intersubunit beta-sheet in the functional hKAT II dimer. Moreover, the N-terminal regions of hKAT II and aspartate aminotransferase appear to have converged to highly similar although 2-fold symmetry-related conformations, which fulfill the same functional role. A detailed structural comparison of hKAT I and hKAT II reveals a larger and more aliphatic character to the active site of hKAT II due to the absence of the aromatic cage involved in ligand binding in hKAT I. The observed structural differences could be exploited for the rational design of highly selective hKAT II inhibitors.
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Affiliation(s)
- Franca Rossi
- DiSCAFF-INFM, University of Piemonte Orientale "A. Avogadro", 28100 Novara, Italy
| | - Silvia Garavaglia
- DiSCAFF-INFM, University of Piemonte Orientale "A. Avogadro", 28100 Novara, Italy
| | - Valeria Montalbano
- DiSCAFF-INFM, University of Piemonte Orientale "A. Avogadro", 28100 Novara, Italy
| | - Martin A Walsh
- Medical Research Council France, c/o European Synchrotron Radiation Facility, 38043 Grenoble Cedex, France
| | - Menico Rizzi
- DiSCAFF-INFM, University of Piemonte Orientale "A. Avogadro", 28100 Novara, Italy.
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