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Solomou G, Finch A, Asghar A, Bardella C. Mutant IDH in Gliomas: Role in Cancer and Treatment Options. Cancers (Basel) 2023; 15:cancers15112883. [PMID: 37296846 DOI: 10.3390/cancers15112883] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2023] [Revised: 05/18/2023] [Accepted: 05/19/2023] [Indexed: 06/12/2023] Open
Abstract
Altered metabolism is a common feature of many cancers and, in some cases, is a consequence of mutation in metabolic genes, such as the ones involved in the TCA cycle. Isocitrate dehydrogenase (IDH) is mutated in many gliomas and other cancers. Physiologically, IDH converts isocitrate to α-ketoglutarate (α-KG), but when mutated, IDH reduces α-KG to D2-hydroxyglutarate (D2-HG). D2-HG accumulates at elevated levels in IDH mutant tumours, and in the last decade, a massive effort has been made to develop small inhibitors targeting mutant IDH. In this review, we summarise the current knowledge about the cellular and molecular consequences of IDH mutations and the therapeutic approaches developed to target IDH mutant tumours, focusing on gliomas.
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Affiliation(s)
- Georgios Solomou
- Institute of Cancer and Genomic Sciences, College of Medical and Dental Sciences, University of Birmingham, Birmingham, B15 2TT, UK
- Division of Academic Neurosurgery, Department of Clinical Neurosciences, University of Cambridge, Cambridge CB2 0QQ, UK
- Wellcome MRC Cambridge Stem Cell Institute, University of Cambridge, Cambridge CB2 0AW, UK
| | - Alina Finch
- Institute of Cancer and Genomic Sciences, College of Medical and Dental Sciences, University of Birmingham, Birmingham, B15 2TT, UK
| | - Asim Asghar
- Institute of Cancer and Genomic Sciences, College of Medical and Dental Sciences, University of Birmingham, Birmingham, B15 2TT, UK
| | - Chiara Bardella
- Institute of Cancer and Genomic Sciences, College of Medical and Dental Sciences, University of Birmingham, Birmingham, B15 2TT, UK
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2
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Atalay EB, Senturk S, Kayali HA. Wild-type IDH1 Knockout Leads to G0/G1 Arrest, Impairs Cancer Cell Proliferation, Altering Glycolysis, and the TCA Cycle in Colon Cancer. Biochem Genet 2023:10.1007/s10528-022-10325-1. [PMID: 36633771 DOI: 10.1007/s10528-022-10325-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2022] [Accepted: 12/28/2022] [Indexed: 01/13/2023]
Abstract
The isocitrate dehydrogenase (IDH), which participates in the TCA cycle, is an important key enzyme in regulating cell metabolism. The effect of the metabolic IDH enzyme on cancer pathogenesis has recently been shown in different types of cancer. However, the role of wild-type (wt) IDH1 in the development of colon cancer is still unknown. Our study investigated the role of the IDH1 enzyme in key hallmarks of colon cancer using various methods such as wound healing, cell cycle, colony formation ability, invasion, and apoptosis analysis. Furthermore, cell metabolism was investigated by pyruvate analysis, dinitrosalicylic acid, and HPLC methods. In addition, CRISPR/Cas9 tool was utilized to knockout the IDH1 gene in colon adenocarcinoma cells (SW620). Further studies were performed in two isogenic IDH1 KO clones. Our findings in both clones suggest that IDH1 KO results in G0/G1 arrest, and reduces proliferation by approximately twofold compared to IDH1 WT cells. In addition, the invasion, migration, and colony formation abilities of IDH1 KO clones were significantly decreased accompanied by significant morphological changes. In the context of metabolism, intracellular glucose, pyruvate, αKG, and malate levels were decreased, while the intracellular citrate level was increased in IDH1 KO clones as compared to IDH1 WT cells. Our results reveal that wt IDH1 knockout leads to a decrease in the aggressive features of colon cancer cells. In conclusion, we reported that wt IDH1 has an effective role in colon cancer progression and could be a potential therapeutic target.
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Affiliation(s)
- Esra Bulut Atalay
- Izmir Biomedicine and Genome Center, Izmir, 35340, Turkey
- Izmir International Biomedicine and Genome Institute (IBG), Dokuz Eylül University, Mithatpasa St. No: 58/5, Balcova, 35340, Izmir, Turkey
| | - Serif Senturk
- Izmir Biomedicine and Genome Center, Izmir, 35340, Turkey
- Izmir International Biomedicine and Genome Institute (IBG), Dokuz Eylül University, Mithatpasa St. No: 58/5, Balcova, 35340, Izmir, Turkey
| | - Hulya Ayar Kayali
- Izmir Biomedicine and Genome Center, Izmir, 35340, Turkey.
- Izmir International Biomedicine and Genome Institute (IBG), Dokuz Eylül University, Mithatpasa St. No: 58/5, Balcova, 35340, Izmir, Turkey.
- Department of Chemistry, Division of Biochemistry, Faculty of Science, Dokuz Eylul University, 35160, İzmir, Turkey.
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Fan X, Wang X, Liu XR, Li KX, Liu Y. Effects of ferulic acid on regulating the neurovascular unit: Implications for ischemic stroke treatment. WORLD JOURNAL OF TRADITIONAL CHINESE MEDICINE 2022. [DOI: 10.4103/wjtcm.wjtcm_76_21] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022] Open
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Kang JB, Park DJ, Koh PO. Identification of proteins differentially expressed by glutamate treatment in cerebral cortex of neonatal rats. Lab Anim Res 2019; 35:24. [PMID: 32257912 PMCID: PMC7081608 DOI: 10.1186/s42826-019-0026-9] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2019] [Accepted: 11/12/2019] [Indexed: 11/22/2022] Open
Abstract
Glutamate leads to neuronal cell damage by generating neurotoxicity during brain development. The objective of this study is to identify proteins that differently expressed by glutamate treatment in neonatal cerebral cortex. Sprague-Dawley rat pups (post-natal day 7) were intraperitoneally injected with vehicle or glutamate (10 mg/kg). Brain tissues were isolated 4 h after drug treatment and fixed for morphological study. Moreover, cerebral cortices were collected for protein study. Two-dimensional gel electrophoresis and mass spectrometry were carried out to identify specific proteins. We observed severe histopathological changes in glutamate-exposed cerebral cortex. We identified various proteins that differentially expressed by glutamate exposure. Identified proteins were thioredoxin, peroxiredoxin 5, ubiquitin carboxy-terminal hydrolase L1, proteasome subunit alpha proteins, isocitrate dehydrogenase, and heat shock protein 60. Heat shock protein 60 was increased in glutamate exposed condition. However, other proteins were decreased in glutamate-treated animals. These proteins are related to anti-oxidant, protein degradation, metabolism, signal transduction, and anti-apoptotic function. Thus, our findings can suggest that glutamate leads to neonatal cerebral cortex damage by regulation of specific proteins that mediated with various functions.
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Affiliation(s)
- Ju-Bin Kang
- Department of Anatomy, College of Veterinary Medicine, Research Institute of Life Science, Gyeongsang National University, 501 Jinju-daero, Jinju, 52828 South Korea
| | - Dong-Ju Park
- Department of Anatomy, College of Veterinary Medicine, Research Institute of Life Science, Gyeongsang National University, 501 Jinju-daero, Jinju, 52828 South Korea
| | - Phil-Ok Koh
- Department of Anatomy, College of Veterinary Medicine, Research Institute of Life Science, Gyeongsang National University, 501 Jinju-daero, Jinju, 52828 South Korea
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5
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Maruyama Y, Toya Y, Kurokawa H, Fukano Y, Sato A, Umemura H, Yamada K, Iwasaki H, Tobori N, Shimizu H. Characterization of oil-producing yeast Lipomyces starkeyi on glycerol carbon source based on metabolomics and 13C-labeling. Appl Microbiol Biotechnol 2018; 102:8909-8920. [PMID: 30097695 DOI: 10.1007/s00253-018-9261-5] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2018] [Revised: 05/30/2018] [Accepted: 07/19/2018] [Indexed: 11/27/2022]
Abstract
Lipomyces starkeyi is an oil-producing yeast that can produce triacylglycerol (TAG) from glycerol as a carbon source. The TAG was mainly produced after nitrogen depletion alongside reduced cell proliferation. To obtain clues for enhancing the TAG production, cell metabolism during the TAG-producing phase was characterized by metabolomics with 13C labeling. The turnover analysis showed that the time constants of intermediates from glycerol to pyruvate (Pyr) were large, whereas those of tricarboxylic acid (TCA) cycle intermediates were much smaller than that of Pyr. Surprisingly, the time constants of intermediates in gluconeogenesis and the pentose phosphate (PP) pathway were large, suggesting that a large amount of the uptaken glycerol was metabolized via the PP pathway. To synthesize fatty acids that make up TAG from acetyl-CoA (AcCoA), 14 molecules of nicotinamide adenine dinucleotide phosphate (NADPH) per C16 fatty acid molecule are required. Because the oxidative PP pathway generates NADPH, this pathway would contribute to supply NADPH for fatty acid synthesis. To confirm that the oxidative PP pathway can supply the NADPH required for TAG production, flux analysis was conducted based on the measured specific rates and mass balances. Flux analysis revealed that the NADPH necessary for TAG production was supplied by metabolizing 48.2% of the uptaken glycerol through gluconeogenesis and the PP pathway. This result was consistent with the result of the 13C-labeling experiment. Furthermore, comparison of the actual flux distribution with the ideal flux distribution for TAG production suggested that it is necessary to flow more dihydroxyacetonephosphate (DHAP) through gluconeogenesis to improve TAG yield.
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Affiliation(s)
- Yuki Maruyama
- Analytical Technology Research Center, Research and Development Headquarters, Lion Corporation, 7-2-1 Hirai, Edogawa-ku, Tokyo, 132-0035, Japan.
| | - Yoshihiro Toya
- Department of Bioinformatic Engineering, Graduate School of Information Science and Technology, Osaka University, 1-5 Yamadaoka, Suita, Osaka, 565-0871, Japan
| | - Hiroshi Kurokawa
- Functional Materials Science Research Laboratories, Research and Development Headquarters, Lion Corporation, 7-2-1 Hirai, Edogawa-ku, Tokyo, 132-0035, Japan
| | - Yuka Fukano
- Functional Materials Science Research Laboratories, Research and Development Headquarters, Lion Corporation, 7-2-1 Hirai, Edogawa-ku, Tokyo, 132-0035, Japan
| | - Atsushi Sato
- Analytical Technology Research Center, Research and Development Headquarters, Lion Corporation, 7-2-1 Hirai, Edogawa-ku, Tokyo, 132-0035, Japan
| | - Hiroyasu Umemura
- Analytical Technology Research Center, Research and Development Headquarters, Lion Corporation, 7-2-1 Hirai, Edogawa-ku, Tokyo, 132-0035, Japan
| | - Kaoru Yamada
- Analytical Technology Research Center, Research and Development Headquarters, Lion Corporation, 7-2-1 Hirai, Edogawa-ku, Tokyo, 132-0035, Japan
| | - Hideaki Iwasaki
- Analytical Technology Research Center, Research and Development Headquarters, Lion Corporation, 7-2-1 Hirai, Edogawa-ku, Tokyo, 132-0035, Japan
| | - Norio Tobori
- Functional Materials Science Research Laboratories, Research and Development Headquarters, Lion Corporation, 7-2-1 Hirai, Edogawa-ku, Tokyo, 132-0035, Japan
| | - Hiroshi Shimizu
- Department of Bioinformatic Engineering, Graduate School of Information Science and Technology, Osaka University, 1-5 Yamadaoka, Suita, Osaka, 565-0871, Japan
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Al-Khallaf H. Isocitrate dehydrogenases in physiology and cancer: biochemical and molecular insight. Cell Biosci 2017; 7:37. [PMID: 28785398 PMCID: PMC5543436 DOI: 10.1186/s13578-017-0165-3] [Citation(s) in RCA: 56] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2017] [Accepted: 08/01/2017] [Indexed: 01/31/2023] Open
Abstract
Isocitrate dehydrogenases play important roles in cellular metabolism and cancer. This review will discuss how the roles of isoforms 1 and 2 in normal cell and cancer metabolism are distinct from those of isoform 3. It will also explain why, unlike 1 and 2, mutations in isoform 3 in tumor are not likely to be driver ones. A model explaining two important features of isocitrate dehydrogenases 1 and 2 mutations, their dominant negative effect and their mutual exclusivity, will be provided. The importance of targeting these mutations and the possibility of augmenting such therapy by targeting other cancer-related pathways will also be discussed.
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Affiliation(s)
- Hamoud Al-Khallaf
- Department of Pathology and Laboratory Medicine, King Fahad Specialist Hospital, 6830 Ammar Bin Thabit St, Al Muraikabat, Dammam, 32253 Saudi Arabia
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Shah FA, Gim SA, Sung JH, Jeon SJ, Kim MO, Koh PO. Identification of proteins regulated by curcumin in cerebral ischemia. J Surg Res 2016; 201:141-8. [DOI: 10.1016/j.jss.2015.10.025] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2015] [Revised: 10/08/2015] [Accepted: 10/14/2015] [Indexed: 01/01/2023]
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Kesten D, Kummer U, Sahle S, Hübner K. A new model for the aerobic metabolism of yeast allows the detailed analysis of the metabolic regulation during glucose pulse. Biophys Chem 2015; 206:40-57. [DOI: 10.1016/j.bpc.2015.06.010] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2015] [Revised: 06/23/2015] [Accepted: 06/25/2015] [Indexed: 01/08/2023]
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9
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Identification of proteins in hyperglycemia and stroke animal models. J Surg Res 2015; 200:365-73. [PMID: 26265382 DOI: 10.1016/j.jss.2015.07.020] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2015] [Revised: 07/08/2015] [Accepted: 07/09/2015] [Indexed: 01/23/2023]
Abstract
BACKGROUND Stroke is a major cause of disability and death in adults. Diabetes mellitus is a metabolic disorder that strongly increases the risk of severe vascular diseases. This study compared changes in proteins of the cerebral cortex during ischemic brain injury between nondiabetic and diabetic animals. METHODS Adult male rats were injected with streptozotocin (40 mg/kg) via the intraperitoneal route to induce diabetes and underwent surgical middle cerebral artery occlusion (MCAO) 4 wk after streptozotocin treatment. Cerebral cortex tissues were collected 24 h after MCAO and cerebral cortex proteins were analyzed by two-dimensional gel electrophoresis and mass spectrometry. RESULTS Several proteins were identified as differentially expressed between nondiabetic and diabetic animals. Among the identified proteins, we focused on the following metabolism-related enzymes: isocitrate dehydrogenase, glyceraldehyde-3-phosphate dehydrogenase, adenosylhomocysteinase, pyruvate kinase, and glucose-6-phosphate isomerase (neuroleukin). Expression of these proteins was decreased in animals that underwent MCAO. Moreover, protein expression was reduced to a greater extent in diabetic animals than in nondiabetic animals. Reverse transcription-polymerase chain reaction analysis confirmed that the diabetic condition exacerbates the decrease in expression of metabolism-related proteins after MCAO. CONCLUSIONS These results suggest that the diabetic condition may exacerbate brain damage during focal cerebral ischemia through the downregulation of metabolism-related proteins.
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Shah FA, Gim SA, Kim MO, Koh PO. Proteomic identification of proteins differentially expressed in response to resveratrol treatment in middle cerebral artery occlusion stroke model. J Vet Med Sci 2014; 76:1367-74. [PMID: 24998396 PMCID: PMC4221170 DOI: 10.1292/jvms.14-0169] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Resveratrol has a
neuroprotective effect against cerebral ischemia. The objective of this study was to
identify proteins that are differentially expressed in the cerebral cortex of vehicle- and
resveratrol-treated animals during ischemic injury. Focal cerebral ischemia was induced as
middle cerebral artery occlusion (MCAO) in male rats. Rats were treated with vehicle or
resveratrol before MCAO, and cerebral cortex was collected 24 hr after MCAO. Cerebral
cortex proteins were identified by two-dimensional gel electrophoresis and mass
spectrometry. Several proteins were identified as differentially expressed between
vehicle- and resveratrol-treated animals. Among these proteins, expression of
peroxiredoxin-5, isocitrate dehydrogenase [NAD+], apolipoprotein A-I and
ubiquitin carboxy terminal hydrolase L1 was decreased in the vehicle-treated group,
whereas resveratrol attenuated the injury-induced decrease in expression of these
proteins. However, expression of collapsing response mediator protein 2 was increased in
the vehicle-treated group, whereas resveratrol prevented the injury-induced increase in
the expression of this protein. These findings suggest that resveratrol modulates the
expression of various proteins that associated with oxidative stress and energy metabolism
in focal cerebral ischemia.
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Affiliation(s)
- Fawad-Ali Shah
- Department of Anatomy, College of Veterinary Medicine, Research Institute of Life Science, Gyeongsang National University, Jinju, South Korea
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11
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Losman JA, Kaelin WG. What a difference a hydroxyl makes: mutant IDH, (R)-2-hydroxyglutarate, and cancer. Genes Dev 2013; 27:836-52. [PMID: 23630074 DOI: 10.1101/gad.217406.113] [Citation(s) in RCA: 446] [Impact Index Per Article: 40.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Mutations in metabolic enzymes, including isocitrate dehydrogenase 1 (IDH1) and IDH2, in cancer strongly implicate altered metabolism in tumorigenesis. IDH1 and IDH2 catalyze the interconversion of isocitrate and 2-oxoglutarate (2OG). 2OG is a TCA cycle intermediate and an essential cofactor for many enzymes, including JmjC domain-containing histone demethylases, TET 5-methylcytosine hydroxylases, and EglN prolyl-4-hydroxylases. Cancer-associated IDH mutations alter the enzymes such that they reduce 2OG to the structurally similar metabolite (R)-2-hydroxyglutarate [(R)-2HG]. Here we review what is known about the molecular mechanisms of transformation by mutant IDH and discuss their implications for the development of targeted therapies to treat IDH mutant malignancies.
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Affiliation(s)
- Julie-Aurore Losman
- Department of Medical Oncology, Dana-Farber Cancer Institute, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts 02215, USA
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12
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Sung JH, Cho EH, Cho JH, Won CK, Kim MO, Koh PO. Identification of proteins regulated by ferulic acid in a middle cerebral artery occlusion animal model-a proteomics approach. J Vet Med Sci 2012; 74:1401-7. [PMID: 22785056 DOI: 10.1292/jvms.12-0063] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Ferulic acid plays a neuroprotective role in cerebral ischemia. The aim of this study was to identify the proteins that are differentially expressed following ferulic acid treatment during ischemic brain injury using a proteomics technique. Middle cerebral artery occlusion (MCAO) was performed to induce a focal cerebral ischemic injury in adult male rats, and ferulic acid (100 mg/kg) or vehicle was administered immediately after MCAO. Brain tissues were collected 24 hr after MCAO. The proteins in the cerebral cortex were separated using two-dimensional gel electrophoresis and were identified by mass spectrometry. We detected differentially expressed proteins between vehicle- and ferulic acid-treated animals. Adenosylhomocysteinase, isocitrate dehydrogenase [NAD(+)], mitogen-activated protein kinase kinase 1 and glyceraldehyde-3-phosphate dehydrogenase were decreased in the vehicle-treated group, and ferulic acid prevented the injury-induced decreases in these proteins. However, pyridoxal phosphate phosphatase and heat shock protein 60 were increased in the vehicle-treated group, while ferulic acid prevented the injury-induced increase in these proteins. It is accepted that these enzymes are involved in cellular metabolism and differentiation. Thus, these findings suggest evidence that ferulic acid plays a neuroprotective role against focal cerebral ischemia through the up- and down-modulation of specific enzymes.
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Affiliation(s)
- Jin-Hee Sung
- Department of Anatomy, College of Veterinary Medicine and Research Institute of Life Science, Gyeongsang National University, Jinju, South Korea
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Ligand binding and structural changes associated with allostery in yeast NAD(+)-specific isocitrate dehydrogenase. Arch Biochem Biophys 2011; 519:112-7. [PMID: 22008468 DOI: 10.1016/j.abb.2011.10.003] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2011] [Revised: 09/30/2011] [Accepted: 10/03/2011] [Indexed: 11/20/2022]
Abstract
Yeast NAD(+)-specific isocitrate dehydrogenase (IDH) is an octameric enzyme composed of four each of regulatory IDH1 and catalytic IDH2 subunits that share 42% sequence identity. IDH2 contains catalytic isocitrate/Mg2+ and NAD+ binding sites whereas IDH1 contains homologous binding sites, respectively, for cooperative binding of isocitrate and for allosteric binding of AMP. Ligand binding is highly ordered in vitro, and IDH exhibits the unusual property of half-site binding for all ligands. The structures of IDH solved in the absence or presence of ligands have shown: (a) a heterodimer to be the basic structural/functional unit of the enzyme, (b) the organization of heterodimers to form tetramer and octamer structures, (c) structural differences that may underlie cooperative and allosteric regulatory mechanisms, and (d) the possibility for formation of a disulfide bond that could reduce catalytic activity. In vivo analyses of mutant enzymes have elucidated the physiological importance of catalytic activity and allosteric regulation of this tricarboxylic acid cycle enzyme. Other studies have established the importance of a disulfide bond in regulation of IDH activity in vivo, as well as contributions of this bond to the property of half-site ligand binding exhibited by the wild-type enzyme.
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14
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Simcock DC, Walker LR, Pedley KC, Simpson HV, Brown S. The tricarboxylic acid cycle in L₃ Teladorsagia circumcincta: metabolism of acetyl CoA to succinyl CoA. Exp Parasitol 2011; 128:68-75. [PMID: 21320492 DOI: 10.1016/j.exppara.2011.02.008] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2010] [Revised: 02/02/2011] [Accepted: 02/08/2011] [Indexed: 11/30/2022]
Abstract
Nematodes, like other species, derive much of the energy for cellular processes from mitochondrial pathways including the TCA cycle. Previously, we have shown L₃ Teladorsagia circumcincta consume oxygen and so may utilise a full TCA cycle for aerobic energy metabolism. We have assessed the relative activity levels and substrate affinities of citrate synthase, aconitase, isocitrate dehydrogenase (both NAD+ and NADP+ specific) and α-ketoglutarate dehydrogenase in homogenates of L₃ T. circumcincta. All of these enzymes were present in homogenates. Compared with citrate synthase, low levels of enzyme activity and low catalytic efficiency was observed for NAD+ isocitrate dehydrogenase and especially α-ketoglutarate dehydrogenase. Therefore, it is likely that the activity of these to enzymes regulate overall metabolite flow through the TCA cycle, especially when [NAD+] limits enzyme activity. Of the enzymes tested, only citrate synthase had substrate affinities which were markedly different from values obtained from mammalian species. Overall, the results are consistent with the suggestion that a full TCA cycle exists withinL₃ T. circumcincta. While there may subtle variations in enzyme properties, particularly for citrate synthase, the control points for the TCA cycle inL₃ T. circumcincta are probably similar to those in the tissues of their host species.
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Affiliation(s)
- D C Simcock
- Institute of Food Nutrition and Human Health, Massey University, Palmerston North 4442, New Zealand.
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15
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Detection and localisation of protein–protein interactions in Saccharomyces cerevisiae using a split-GFP method. Fungal Genet Biol 2008; 45:597-604. [DOI: 10.1016/j.fgb.2008.01.003] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2007] [Revised: 10/23/2007] [Accepted: 01/07/2008] [Indexed: 11/23/2022]
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16
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Lin AP, Hakala KW, Weintraub ST, McAlister-Henn L. Suppression of metabolic defects of yeast isocitrate dehydrogenase and aconitase mutants by loss of citrate synthase. Arch Biochem Biophys 2008; 474:205-12. [PMID: 18359281 DOI: 10.1016/j.abb.2008.03.005] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2008] [Revised: 03/05/2008] [Accepted: 03/05/2008] [Indexed: 11/15/2022]
Abstract
Yeast mutants lacking mitochondrial NAD(+)-specific isocitrate dehydrogenase (idhDelta) or aconitase (aco1Delta) were found to share several growth phenotypes as well as patterns of specific protein expression that differed from the parental strain. These shared properties of idhDelta and aco1Delta strains were eliminated or moderated by co-disruption of the CIT1 gene encoding mitochondrial citrate synthase. Gas chromatography/mass spectrometry analyses indicated a particularly dramatic increase in cellular citrate levels in idhDelta and aco1Delta strains, whereas citrate levels were substantially lower in idhDeltacit1Delta and aco1Deltacit1Delta strains. Exogenous addition of citrate to parental strain cultures partially recapitulated effects of high endogenous levels of citrate in idhDelta and aco1Delta strains. Finally, effects of elevated cellular citrate in idhDelta and aco1Delta mutant strains were partially alleviated by addition of iron or by an increase in pH of the growth medium, suggesting that detrimental effects of citrate are due to elevated levels of the ionized form of this metabolite.
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Affiliation(s)
- An-Ping Lin
- Department of Biochemistry, University of Texas Health Science Center, 7703 Floyd Curl Dr., San Antonio, TX 78229-3900, USA
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17
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Taylor AB, Hu G, Hart PJ, McAlister-Henn L. Allosteric motions in structures of yeast NAD+-specific isocitrate dehydrogenase. J Biol Chem 2008; 283:10872-80. [PMID: 18256028 DOI: 10.1074/jbc.m708719200] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Mitochondrial NAD(+)-specific isocitrate dehydrogenases (IDHs) are key regulators of flux through biosynthetic and oxidative pathways in response to cellular energy levels. Here we present the first structures of a eukaryotic member of this enzyme family, the allosteric, hetero-octameric, NAD(+)-specific IDH from yeast in three forms: 1) without ligands, 2) with bound analog citrate, and 3) with bound citrate + AMP. The structures reveal the molecular basis for ligand binding to homologous but distinct regulatory and catalytic sites positioned at the interfaces between IDH1 and IDH2 subunits and define pathways of communication between heterodimers and heterotetramers in the hetero-octamer. Disulfide bonds observed at the heterotetrameric interfaces in the unliganded IDH hetero-octamer are reduced in the ligand-bound forms, suggesting a redox regulatory mechanism that may be analogous to the "on-off" regulation of non-allosteric bacterial IDHs via phosphorylation. The results strongly suggest that eukaryotic IDH enzymes are exquisitely tuned to ensure that allosteric activation occurs only when concentrations of isocitrate are elevated.
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Affiliation(s)
- Alexander B Taylor
- Department of Biochemistry and X-ray Crystallography Core Laboratory, The University of Texas Health Science Center, San Antonio, Texas 78229, USA
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18
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Hu G, McAlister-Henn L. Novel allosteric properties produced by residue substitutions in the subunit interface of yeast NAD+-specific isocitrate dehydrogenase. Arch Biochem Biophys 2006; 453:207-16. [PMID: 16884682 DOI: 10.1016/j.abb.2006.06.022] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2006] [Revised: 06/23/2006] [Accepted: 06/25/2006] [Indexed: 10/24/2022]
Abstract
Yeast NAD+-specific isocitrate dehydrogenase (IDH) is an octamer of four IDH1 and four IDH2 subunits, and the basic structural unit of the enzyme is an IDH1/IDH2 heterodimer. To investigate one aspect of the interaction between IDH1 and IDH2, residues in a hydrophobic region at the heterodimer interface (Val-216, Ser-220, and Val-224 in IDH1; Ile-221, Val-225, and Val-229 in IDH2) were replaced by alanine residues in each and in both subunits. Gel filtration and sedimentation velocity analyses demonstrated that the residue substitutions do not disrupt the octameric structure of IDH. However, these substitutions produce novel kinetic properties including, with respect to cofactor, positive allosteric regulation by AMP and cooperativity in the absence of AMP. These allosteric properties are also apparent in NAD+-binding experiments. Despite substantial measurable activity for the mutant enzyme containing residue substitutions in both subunits, expression of this enzyme produces growth phenotypes indicative of IDH dysfunction in vivo.
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Affiliation(s)
- Gang Hu
- Department of Biochemistry, University of Texas Health Science Center, San Antonio, TX 78229-3900, USA
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Hu G, Lin AP, McAlister-Henn L. Physiological consequences of loss of allosteric activation of yeast NAD+-specific isocitrate dehydrogenase. J Biol Chem 2006; 281:16935-16942. [PMID: 16621803 DOI: 10.1074/jbc.m512281200] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Based on allosteric regulatory properties, NAD+-specific isocitrate dehydrogenase (IDH) is believed to control flux through the tricarboxylic acid cycle in vivo. To distinguish growth phenotypes associated with regulatory dysfunction of this enzyme in Saccharomyces cerevisiae, we analyzed strains expressing well defined mutant forms of IDH or a non-allosteric bacterial NAD+-specific isocitrate dehydrogenase (IDHa). As previously reported, expression of mutant forms of IDH with severe catalytic defects but intact regulatory properties produced an inability to grow with acetate as the carbon source and a dramatic increase in the frequency of generation of petite colonies, phenotypes also exhibited by a strain (idh1Deltaidh2Delta) lacking IDH. Reduced growth rates on acetate medium were also observed with expression of enzymes with severe regulatory defects or of the bacterial IDHa enzyme, suggesting that allosteric regulation is also important for optimal growth on this carbon source. However, expression of IDHa produced no effect on petite frequency, suggesting that the intermediate petite frequencies observed for strains expressing regulatory mutant forms of IDH are likely to correlate with the slight reductions in catalytic efficiency observed for these enzymes. Finally, rates of increase in oxygen consumption were measured during culture shifts from medium with glucose to medium with ethanol as the carbon source. Strains expressing wild-type or catalytically deficient mutant forms of IDH exhibited rapid respiratory transitions, whereas strains expressing regulatory mutant forms of IDH or the bacterial IDHa enzyme exhibited much slower respiratory transitions. This suggests an important physiological role for allosteric activation of IDH during changes in environmental conditions.
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Affiliation(s)
- Gang Hu
- Department of Biochemistry, University of Texas Health Science Center, San Antonio, Texas 78229-3900
| | - An-Ping Lin
- Department of Biochemistry, University of Texas Health Science Center, San Antonio, Texas 78229-3900
| | - Lee McAlister-Henn
- Department of Biochemistry, University of Texas Health Science Center, San Antonio, Texas 78229-3900.
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Contreras-Shannon V, Lin AP, McCammon MT, McAlister-Henn L. Kinetic properties and metabolic contributions of yeast mitochondrial and cytosolic NADP+-specific isocitrate dehydrogenases. J Biol Chem 2004; 280:4469-75. [PMID: 15574419 DOI: 10.1074/jbc.m410140200] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
To compare kinetic properties of homologous isozymes of NADP+-specific isocitrate dehydrogenase, histidine-tagged forms of yeast mitochondrial (IDP1) and cytosolic (IDP2) enzymes were expressed and purified. The isozymes were found to share similar apparent affinities for cofactors. However, with respect to isocitrate, IDP1 had an apparent Km value approximately 7-fold lower than that of IDP2, whereas, with respect to alpha-ketoglutarate, IDP2 had an apparent Km value approximately 10-fold lower than that of IDP1. Similar Km values for substrates and cofactors in decarboxylation and carboxylation reactions were obtained for IDP2, suggesting a capacity for bidirectional catalysis in vivo. Concentrations of isocitrate and alpha-ketoglutarate measured in extracts from the parental strain were found to be similar with growth on different carbon sources. For mutant strains lacking IDP1, IDP2, and/or the mitochondrial NAD+-specific isocitrate dehydrogenase (IDH), metabolite measurements indicated that major cellular flux is through the IDH-catalyzed reaction in glucose-grown cells and through the IDP2-catalyzed reaction in cells grown with a nonfermentable carbon source (glycerol and lactate). A substantial cellular pool of alpha-ketoglutarate is attributed to IDH function during glucose growth, and to both IDP1 and IDH function during growth on glycerol/lactate. Complementation experiments using a strain lacking IDH demonstrated that overexpression of IDP1 partially compensated for the glutamate auxotrophy associated with loss of IDH. Collectively, these results suggest an ancillary role for IDP1 in cellular glutamate synthesis and a role for IDP2 in equilibrating and maintaining cellular levels of isocitrate and alpha-ketoglutarate.
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Affiliation(s)
- Veronica Contreras-Shannon
- Department of Biochemistry, University of Texas Health Science Center, San Antonio, Texas 78229-3900, USA
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Okamoto K, Matsuzaka Y, Yoshikawa Y, Takaki A, Kulski JK, Tamiya G, Inoko H. Identification of NAD+-dependent isocitrate dehydrogenase 3 gamma-like (IDH3GL) gene and its genetic polymorphisms. Gene 2004; 323:141-8. [PMID: 14659887 DOI: 10.1016/j.gene.2003.09.014] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
We have identified a novel human gene designated as IDH3GL (isocitrate dehydrogenase 3 gamma-like) that is expressed specifically in human testis. The gene corresponds in sequence to an EST (expressed sequence tag) A1476435 that was first detected by differential expression analysis using a microarray assay. The full-length cDNA sequence (1037 bp) was isolated from the human testis 5'-3'-RACE cDNA libraries and found to have 83% nucleotide sequence identity with part of the IDH3G (isocitrate dehydrogenase 3 gamma). The IDH3GL gene consists of 3 exons spanning approximately 220 kb within the region of the NELL1 gene on chromosome 11p15.1. Sequence analysis of the IDH3GL cDNA revealed the presence of a premature stop codon at nucleotide positions 337-339 that results in a truncated peptide with 112 amino acids. This stop codon is conserved in various human ethnic populations and in the chimpanzee (Pan troglodytes). In order to assess the functional status of IDH3GL, especially in relation to the presence of the putative premature stop codon, single nucleotide polymorphisms (SNPs) were screened in the upstream, coding and non-coding regions of the IDH3GL gene in a Japanese population. As a result, a total of 10 SNPs were identified, seven were novel and one of them was a non-synonymous amino acid substitution from Leu to Val. We conclude that the IDH3GL gene sequence is a splice variant of the NELL1 gene and that it probably evolved from a transposed pseudogene of the IDH3 gene.
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Affiliation(s)
- Koichi Okamoto
- Department of Genetic Information, Division of Molecular Life Science, Tokai University School of Medicine, Bohseidai, Kanagawa 259-1193, Isehara, Japan
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Lin AP, McAlister-Henn L. Isocitrate binding at two functionally distinct sites in yeast NAD+-specific isocitrate dehydrogenase. J Biol Chem 2002; 277:22475-83. [PMID: 11953438 DOI: 10.1074/jbc.m202534200] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Yeast NAD(+)-specific isocitrate dehydrogenase (IDH) is an octamer containing two types of homologous subunits. Ligand-binding analyses were conducted to examine effects of residue changes in putative catalytic and regulatory isocitrate-binding sites respectively contained in IDH2 and IDH1 subunits. Replacement of homologous serine residues in either subunit site, S98A in IDH2 or S92A in IDH1, was found to reduce by half the total number of holoenzyme isocitrate-binding sites, confirming a correlation between detrimental effects on isocitrate binding and respective kinetic defects in catalysis and allosteric activation by AMP. Replacement of both serine residues eliminates isocitrate binding and measurable catalytic activity. The putative isocitrate-binding sites of IDH1 and IDH2 contain five identical and four nonidentical residues. Reciprocal replacement of the four nonidentical residues in either or both subunits (A108R, F136Y, T241D, and N245D in IDH1 and/or R114A, Y142F, D248T, and D252N in IDH2) was found to be permissive for isocitrate binding. This provides further evidence for two types of binding sites in IDH, although the authentic residues have been shown to be necessary for normal kinetic contributions. Finally, the mutant enzymes with residue replacements in the IDH1 site were found to be unable to bind AMP, suggesting that allosteric activation is dependent both upon binding of isocitrate at the IDH1 site and upon the changes in the enzyme normally elicited by this binding.
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Affiliation(s)
- An-Ping Lin
- Department of Biochemistry, University of Texas Health Science Center, San Antonio, Texas 78229-3900, USA
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24
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Steen IH, Madern D, Karlström M, Lien T, Ladenstein R, Birkeland NK. Comparison of isocitrate dehydrogenase from three hyperthermophiles reveals differences in thermostability, cofactor specificity, oligomeric state, and phylogenetic affiliation. J Biol Chem 2001; 276:43924-31. [PMID: 11533060 DOI: 10.1074/jbc.m105999200] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
With the aim of gaining insight into the molecular and phylogenetic relationships of isocitrate dehydrogenase (IDH) from hyperthermophiles, we carried out a comparative study of putative IDHs identified in the genomes of the eubacterium Thermotoga maritima and the archaea Aeropyrum pernix and Pyrococcus furiosus. An optimum for activity at 90 degrees C or above was found for each IDH. PfIDH and ApIDH were the most thermostable with a melting temperature of 103.7 and 109.9 degrees C, respectively, compared with 98.3 and 98.5 degrees C for TmIDH and AfIDH, respectively. Analytical ultracentrifugation revealed a tetrameric oligomeric state for TmIDH and a homodimeric state for ApIDH and PfIDH. TmIDH and ApIDH were NADP-dependent (K(m)((NADP)) of 55.2 and 44.4 microm, respectively) whereas PfIDH was NAD-dependent (K(m)((NAD)) of 68.3 microm). These data document that TmIDH represents a novel tetrameric NADP-dependent form of IDH and that PfIDH is a homodimeric NAD-dependent IDH not previously found among the archaea. The homodimeric NADP-IDH present in A. pernix is the most common form of IDH known so far. The evolutionary relationships of ApIDH, PfIDH, and TmIDH with all of the available amino acid sequences of di- and multimeric IDHs are described and discussed.
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Affiliation(s)
- I H Steen
- Department of Microbiology, University of Bergen, P. O. Box 7800, Jahnebakken 5, N-5020 Bergen, Norway
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25
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Panisko EA, McAlister-Henn L. Subunit interactions of yeast NAD+-specific isocitrate dehydrogenase. J Biol Chem 2001; 276:1204-10. [PMID: 11042198 DOI: 10.1074/jbc.m005056200] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Yeast mitochondrial NAD(+)-specific isocitrate dehydrogenase is an octamer composed of four each of two nonidentical but related subunits designated IDH1 and IDH2. IDH2 was previously shown to contain the catalytic site, whereas IDH1 contributes regulatory properties including cooperativity with respect to isocitrate and allosteric activation by AMP. In this study, interactions between IDH1 and IDH2 were detected using the yeast two-hybrid system, but interactions between identical subunit polypeptides were not detected with this or other methods. A model for heterodimeric interactions between the subunits is therefore proposed for this enzyme. A corollary of this model, based on the three-dimensional structure of the homologous enzyme from Escherichia coli, is that some interactions between subunits occur at isocitrate binding sites. Based on this model, two residues (Lys-183 and Asp-217) in the regulatory IDH1 subunit were predicted to be important in the catalytic site of IDH2. We found that individually replacing these residues with alanine results in mutant enzymes that exhibit a drastic reduction in catalysis both in vitro and in vivo. Also based on this model, the two analogous residues (Lys-189 and Asp-222) of the catalytic IDH2 subunit were predicted to contribute to the regulatory site of IDH1. A K189A substitution in IDH2 was found to produce a decrease in activation of the enzyme by AMP and a loss of cooperativity with respect to isocitrate. A D222A substitution in IDH2 produces similar regulatory defects and a substantial reduction in V(max) in the absence of AMP. Collectively, these results suggest that the basic structural/functional unit of yeast isocitrate dehydrogenase is a heterodimer of IDH1 and IDH2 subunits and that each subunit contributes to the isocitrate binding site of the other.
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Affiliation(s)
- E A Panisko
- Department of Biochemistry, University of Texas Health Science Center, San Antonio, Texas 78229-3900, USA
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26
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Weiss C, Zeng Y, Huang J, Sobocka MB, Rushbrook JI. Bovine NAD+-dependent isocitrate dehydrogenase: alternative splicing and tissue-dependent expression of subunit 1. Biochemistry 2000; 39:1807-16. [PMID: 10677231 DOI: 10.1021/bi991691i] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
NAD+-dependent isocitrate dehydrogenase (IDH), a key regulatory enzyme in the Krebs cycle, is a multi-tetrameric enzyme. At least three of the subunits in the core tetramer of mammals are unique gene products. Subunits 1/beta and 2/gamma are considered to be regulatory, while subunits 3,4/alpha, comprising half the tetramer, are catalytic. The full sequence was obtained for the major subunit 1 cDNA in bovine heart, IDH 1-A. A second cDNA, rare in heart, was also identified (IDH 1-B). Differences in the two were confined to the 3'-region, suggesting alternative splicing. Screening of brain, kidney, and liver RNA showed the presence of IDH 1-A and 1-B and a third major species, IDH 1-C. Amplification of bovine genomic DNA by PCR across the regions of difference produced a single product. Comparison of the genomic and mRNA sequences showed that IDH 1-A resulted from splicing of exon W to exon Y, eliminating intron w, exon X, and intron x. IDH 1-B was formed by splice junctions between exon W, exon X, and exon Y. IDH 1-C resulted from splicing of exon W to exon X and subsequent retention of intron x. The 2 proteins predicted from these 3 mRNAs are identical over their first 357 residues. Protein IDH 1-A, resulting from a termination codon within exon Y, contains an additional 26 residues. Proteins IDH 1-B and 1-C derive from a common termination codon within exon X and contain an additional 28 residues. The two C-terminal regions differ notably in the number and nature of charged residues, resulting in proteins with a charge difference of 3.2 at pH 7.0. Subunit 1 sequences previously reported from other species grouped with one or the other of the bovine proteins. No evidence was found for alternative splicing in subunit 3,4/alpha. The results of the present study, together with recent work on the 2/gamma subunit [Brenner,V., Nyakatura, G., Rosenthal, A., and Platzer, M. (1998) Genomics 44, 8], indicate that the regulatory subunits of the enzyme, but not the catalytic, possess alternatively spliced forms varying in C-terminal properties with tissue-specific expression. The finding is suggestive of a mechanism for modulation of allosteric regulation tailored to the needs of different tissues.
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Affiliation(s)
- C Weiss
- Department of Biochemistry, State University of New York Downstate Medical Center, 450 Clarkson Avenue, Brooklyn, New York 11203, USA
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27
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Kim YO, Koh HJ, Kim SH, Jo SH, Huh JW, Jeong KS, Lee IJ, Song BJ, Huh TL. Identification and functional characterization of a novel, tissue-specific NAD(+)-dependent isocitrate dehydrogenase beta subunit isoform. J Biol Chem 1999; 274:36866-75. [PMID: 10601238 DOI: 10.1074/jbc.274.52.36866] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
To understand the interactions and functional role of each of the three mitochondrial NAD(+)-dependent isocitrate dehydrogenase (IDH) subunits (alpha, beta, and gamma), we have characterized human cDNAs encoding two beta isoforms (beta(1) and beta(2)) and the gamma subunit. Analysis of deduced amino acid sequences revealed that beta(1) and beta(2) encode 349 and 354 amino acids, respectively, and the two isoforms only differ in the most carboxyl 28 amino acids. The gamma cDNA encodes 354 amino acids and is almost identical to monkey IDHgamma. Northern analyses revealed that the smaller beta(2) transcript (1.3 kilobases) is primarily expressed in heart and skeletal muscle, whereas the larger beta(1) mRNA (1.6 kilobases) is prevalent in nonmuscle tissues. Sequence analysis of the IDHbeta gene indicates that the difference in the C-terminal 28 amino acids between beta(1) and beta(2) proteins results from alternative splicing of a single transcript. Among the various combinations of human IDH subunits co-expressed in bacteria, alphabetagamma, alphabeta, and alphagamma combinations exhibited significant amounts of IDH activity, whereas subunits produced alone and betagamma showed no detectable activity. These data suggest that the alpha is the catalytic subunit and that at least one of the other two subunits plays an essential supporting role for activity. Substitution of beta(1) with beta(2) in the co-expression system lowered the pH optimum for IDH activity from 8.0 to 7.6. This difference in optimal pH was analogous to what was observed in mouse kidney and brain (beta(1) prevalent; optimal pH 8.0) versus heart (beta(2) prevalent; pH 7.6) mitochondria. Experiments with a specially designed splicing reporter construct stably transfected into HT1080 cells indicate that acidic conditions favor a splicing pattern responsible for the muscle- and heart-specific beta(2) isoform. Taken together, these data indicate a regulatory role of IDHbeta isoforms in determining the pH optimum for IDH activity through the tissue-specific alternative splicing.
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Affiliation(s)
- Y O Kim
- Department of Genetic Engineering, College of Natural Sciences, Kyungpook National University, Taegu 702-701, Korea
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28
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Popova TN, Pinheiro de Carvalho MA. Citrate and isocitrate in plant metabolism. BIOCHIMICA ET BIOPHYSICA ACTA 1998; 1364:307-25. [PMID: 9630693 DOI: 10.1016/s0005-2728(98)00008-5] [Citation(s) in RCA: 66] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The relevance of citrate and isocitrate metabolism in plants is discussed in connection with the different pathways for their conversions. The routes for citrate and isocitrate conversions are incorporated into the system of cross-linked metabolic processes and may provide carbon skeletons for nitrogen assimilation and reducing equivalents for biosynthetic reactions, support the functioning of the glyoxylate cycle and play an important role in the TCA and energy metabolism as a whole. The possibility of the coupling of citrate and isocitrate metabolism with various electron transport systems is discussed from the point of view of the efficiency of the balancing cellular NAD(P)H/NAD(P)+ and ATP/ADP ratios. The role of citrate and isocitrate and their derivations as potent effectors of some enzymes is considered. Special attention is paid to the enzymes associated with citrate and isocitrate metabolism and to the mechanisms which regulate their activity. The possibilities of the coordination of the main processes of energy and biosynthetic metabolism at the level of citrate and isocitrate distribution are discussed.
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Affiliation(s)
- T N Popova
- Department of Plant Physiology and Biochemistry, Voronezh State University, 394693 Voronezh, Russian Federation.
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29
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Chen R, Greer AF, Dean AM. Structural constraints in protein engineering--the coenzyme specificity of Escherichia coli isocitrate dehydrogenase. EUROPEAN JOURNAL OF BIOCHEMISTRY 1997; 250:578-82. [PMID: 9428712 DOI: 10.1111/j.1432-1033.1997.0578a.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
In a previous study we reported on the successful inversion of coenzyme specificity in isocitrate dehydrogenase (IDH) from NADP to NAD [Chen, R., Greer, A. & Dean, A. M. (1995) A highly active decarboxylating dehydrogenase with rationally inverted coenzyme specificity, Proc. Natl Acad. Sci. USA 92, 11666-11670]. Here, we explore alternative means to generate NAD dependence in the NADP-dependent scaffold of Escherichia coli IDH. The results reveal that engineering a preference for NAD is constrained by the architecture of the IDH coenzyme binding pocket and confirms that the substituted Asp344 in the engineered enzyme is the major determinant of coenzyme specificity. Mutations in the 316-325 loop, which forms part of the coenzyme binding site, reduce activity through transmission of long-range conformational changes into the active site some 14 A distant. Conformational changes seen upon substituting Cys332-->Tyr are not directly involved with improving activity. Replacements at Cys201 reveal that subtle changes in the packing of hydrophobic residues (Met and Ile versus Leu) can elicit markedly different responses. We caution against using sequence alignments as the sole guide for mutagenesis and show how a combination of rational design of active-site residues based on X-ray structures and random substitutions at surrounding residues provides an efficient means to improve enzyme preference and catalytic efficiency towards novel substrates.
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Affiliation(s)
- R Chen
- Department of Biochemistry, College of Medicine, University of Saskatchewan, Saskatoon, Canada
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30
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Zhao WN, McAlister-Henn L. Affinity purification and kinetic analysis of mutant forms of yeast NAD+-specific isocitrate dehydrogenase. J Biol Chem 1997; 272:21811-7. [PMID: 9268311 DOI: 10.1074/jbc.272.35.21811] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Polyhistidine tags were added to the carboxyl termini of the two homologous subunits of yeast NAD+-specific isocitrate dehydrogenase (IDH). The tag in either the IDH1 or IDH2 subunit permits one-step affinity purification from yeast cellular extracts of catalytically active and allosterically responsive holoenzyme. This expression system was used to investigate subunit-specific contributions of residues with putative functions in adenine nucleotide binding. The primary effect of simultaneous replacement of the adjacent Asp-279 and Ile-280 residues in IDH1 with alanines is a dramatic loss of activation by AMP. In contrast, alanine replacement of the homologous Asp-286 and Ile-287 residues in IDH2 does not alter the allosteric response to AMP, but produces a 160-fold reduction in Vmax due to a 70-fold increase in the S0.5 value for NAD+. These results suggest that the targeted aspartate/isoleucine residues may contribute to regulator binding in IDH1 and to cofactor binding in IDH2, i.e. that these homologous residues are located in regions that have evolved for binding the adenine nucleotide components of different ligands. In other mutant enzymes, an alanine replacement of Asp-191 in IDH1 eliminates measurable catalytic activity, and a similar substitution of the homologous Asp-197 in IDH2 produces pleiotropic catalytic effects. A model is presented for the primary function of IDH2 in catalysis and of IDH1 in regulation, with crucial roles for these single aspartate residues in the communication and functional interdependence of the two subunits.
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Affiliation(s)
- W N Zhao
- Department of Biochemistry, University of Texas Health Science Center, San Antonio, Texas 78284-7760, USA
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31
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Kim H, Mozaffar Z, Weete JD. A dual cofactor-specific isocitrate dehydrogenase from Pythium ultimum. Can J Microbiol 1996; 42:1241-7. [PMID: 8989862 DOI: 10.1139/m96-160] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Isocitrate dehydrogenase is considered to be one of the key regulatory enzymes in the conversion of glucose into fatty acids by oleaginous microorganisms. A dual coenzyme-specific isocitrate dehydrogenase (EC 1.1.1.41) (IDH) was isolated from the primitive fungus Pythium ultimum and purified by 211-fold by sequential ion-exchange, affinity, and gel filtration chromatographies. Specific activity of the partially purified enzyme was 76.2 mumol/(min.mg protein) with NAD+ and 40% less active with NADP+. Optimum pH for activity was 8.5-9.5. K(m) values for threo-D-isocitrate and NAD+ were 0.031 and 0.55 mM, respectively. The estimated molecular mass of the IDH was 96 kDa under nondenaturing conditions and 48 kDa under denaturing conditions, suggesting that the enzyme is composed of two subunits of the same size. The enzyme was relatively stable up to 55 degrees C, but no activity was detected after exposure to 65 degrees C for 15 min. Mg2+ or Mn2+ were required for activity.
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Affiliation(s)
- H Kim
- Department of Botany and Microbiology, Alabama Agricultural Experiment Station, Auburn University 36849, USA
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32
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Zhao WN, McAlister-Henn L. Assembly and Function of a Cytosolic Form of NADH-specific Isocitrate Dehydrogenase in Yeast. J Biol Chem 1996. [DOI: 10.1074/jbc.271.17.10347] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
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Zeng Y, Weiss C, Yao TT, Huang J, Siconolfi-Baez L, Hsu P, Rushbrook JI. Isocitrate dehydrogenase from bovine heart: primary structure of subunit 3/4. Biochem J 1995; 310 ( Pt 2):507-16. [PMID: 7654189 PMCID: PMC1135924 DOI: 10.1042/bj3100507] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Bovine NAD(+)-dependent isocitrate dehydrogenase was shown previously to contain four subunits of approx. 40 kDa (subunits 1-4) possessing different peptide maps and electrophoretic properties [Rushbrook and Harvey (1978) Biochemistry 17, 5339-5346]. In this study the heterogeneity is confirmed using enzyme purified by updated methods and from single animals, ruling out allelic variability. Subunits 1 and 2 were differentiated from each other and from subunits 3 and 4 by N-terminal amino acid sequencing. Subunits 3 and 4 (subunits 3/4) were identical in sequence over 30 residues. The N-terminal residues of subunits 1 and 2 were homologous but not identical with the beta- and gamma-subunits respectively of the comparable pig heart enzyme. Subunits 3/4 were identical over 30 residues with the N-terminus of the pig heart alpha-subunit. Full-length sequence, including that for mitochondrial import, is presented for a protein with the processed N-terminus of subunits 3/4, deduced from cloned cDNA obtained utilizing the N-terminal sequence information. The derived amino acid sequence for the mature protein contains 339 amino acids and has a molecular mass of 36,685 Da. Complete identity with N-terminal and Cys-containing peptides totalling 92 residues from the alpha-subunit of the pig heart enzyme [Huang and Colman (1990) Biochemistry 29, 8266-8273] suggests that maintenance of a particular three-dimensional structure in this subunit is crucial to the function of the enzyme. An electrophoretic heterogeneity within the pig heart alpha-subunit, similar to that shown by bovine subunits 3/4, was demonstrated. One reordering of the Cys-containing peptides of the pig heart alpha-subunit is indicated. Sequence comparison with the distantly related NADP(+)-dependent enzyme from Escherichia coli, for which the three-dimensional structure is known [Stoddard, Dean and Koshland (1993) Biochemistry 32, 9310-9316] shows strong conservation of residues binding isocitrate, Mg2+ and the NAD+ moiety of NADP+, consistent with a catalytic function.
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Affiliation(s)
- Y Zeng
- Department of Biochemistry, State University of New York Health Science Center at Brooklyn 11203, USA
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Nichols BJ, Denton RM. Towards the molecular basis for the regulation of mitochondrial dehydrogenases by calcium ions. Mol Cell Biochem 1995; 149-150:203-12. [PMID: 8569730 DOI: 10.1007/bf01076578] [Citation(s) in RCA: 64] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
In mammalian cells, increases in calcium concentration cause increases in oxidative phosphorylation. This effect is mediated by the activation of four mitochondrial dehydrogenases by calcium ions; FAD-glycerol 3-phosphate dehydrogenase, pyruvate dehydrogenase, NAD-isocitrate dehydrogenase and oxoglutarate dehydrogenase. FAD-glycerol 3-phosphate dehydrogenase, being located on the outer surface of the inner mitochondrial membrane, is exposed to fluctuations in cytoplasmic calcium concentration. The other three enzymes are located within the mitochondrial matrix. While the kinetic properties of all of these enzymes are well characterised, the molecular basis for their regulation by calcium is not. This review uses information derived from calcium binding studies, analysis of conserved calcium binding motifs and comparison of amino acid sequences from calcium sensitive and non-sensitive enzymes to discuss how the recent cloning of several subunits from the four dehydrogenases enhances our understanding of the ways in which these enzymes bind calcium. FAD-glycerol 3-phosphate dehydrogenase binds calcium ions through a domain which is part of the polypeptide chain of the enzyme. In contrast, it is possible that the calcium sensitivity of the other three dehydrogenases may involve separate calcium binding subunits.
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Affiliation(s)
- B J Nichols
- Department of Biochemistry, School of Medical Sciences, University of Bristol, UK
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Kim YO, Oh IU, Park HS, Jeng J, Song BJ, Huh TL. Characterization of a cDNA clone for human NAD(+)-specific isocitrate dehydrogenase alpha-subunit and structural comparison with its isoenzymes from different species. Biochem J 1995; 308 ( Pt 1):63-8. [PMID: 7755589 PMCID: PMC1136843 DOI: 10.1042/bj3080063] [Citation(s) in RCA: 26] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
A 0.6 kb cDNA fragment encoding the human NAD(+)-specific isocitrate dehydrogenase alpha-subunit (H-IDH alpha) was amplified by PCR using oligonucleotide primers synthesized on the basis of pig tryptic peptide sequences [Huang and Colman (1990) Biochemistry 29, 8266-8273]. With the amplified cDNA as a probe, cDNA clones for IDH alpha were isolated from a human heart lambda gt11 cDNA library. The deduced protein sequence of the largest cDNA clone (2628 bp) rendered a precursor protein of 366 amino acids (39,591 Da) and a mature protein of 339 amino acids (36,640 Da). The deduced H-IDH alpha protein sequence is highly similar to the partial peptide sequences of the pig enzyme. It is 55, 43 and 44% identical with yeast NAD(+)-specific IDH2, yeast NAD(+)-specific IDH1 and monkey NAD(+)-specific IDH gamma-subunit (IDH gamma) respectively. However, it has less similarity (about 30%) to NADP(+)-specific IDH from Escherichia coli and bovine mitochondria. These results indicate that the structure of IDH alpha closely resembles that of IDH2, the catalytic subunit of the yeast enzyme. Structural analysis of the deduced H-IDH alpha protein revealed that the amino acids responsible for the binding of isocitrate, Mg2+ and NAD+ are highly conserved. It also has two conserved motifs for the binding sites of ATP and ADP, but a canonical Ca(2+)-binding motif was not recognized. Unusual penta-(ATTTA) and tri-(TAA or ATT) nucleotides which are respectively believed to interact with RNA-binding proteins and be near the endonuclease cleavage sites were frequently recognized in its 3' untranslated region, indicating the possibility of an additional method of regulation of this enzyme. Northern-blot analysis suggests that one mRNA transcript (2.8 kb) exists in cultured HeLa cells. Genomic DNA Southern-blot analysis indicates that the IDH alpha gene is not closely related to that of the other IDH isoenzymes, and IDH alpha appears to be encoded by a single gene.
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Affiliation(s)
- Y O Kim
- Department of Genetic Engineering, College of Natural Sciences, Kyungpook National University, Taegu, Korea
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Nichols BJ, Rigoulet M, Denton RM. Comparison of the effects of Ca2+, adenine nucleotides and pH on the kinetic properties of mitochondrial NAD(+)-isocitrate dehydrogenase and oxoglutarate dehydrogenase from the yeast Saccharomyces cerevisiae and rat heart. Biochem J 1994; 303 ( Pt 2):461-5. [PMID: 7980405 PMCID: PMC1137350 DOI: 10.1042/bj3030461] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
The regulatory properties of NAD(+)-isocitrate dehydrogenase and oxoglutarate dehydrogenase in extracts of yeast and rat heart mitochondria were studied under identical conditions. Yeast NAD(+)-isocitrate dehydrogenase exhibits a low K0.5 for isocitrate and is activated by AMP and ADP, but is insensitive to ATP and Ca2+. In contrast, the rat heart NAD(+)-isocitrate dehydrogenase was insensitive to AMP, but was activated by ADP and by Ca2+ in the presence of ADP or ATP. Both yeast and rat heart oxoglutarate dehydrogenase were stimulated by ADP, but only the heart enzyme was activated by Ca2+. All the enzymes studied were activated by decreases in pH, but to differing extents. The effects of Ca2+, adenine nucleotides and pH were through K0.5 for isocitrate or 2-oxoglutarate. These observations are discussed with reference to the deduced amino acid sequences of the constituent subunits of the enzymes, where they are available.
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Affiliation(s)
- B J Nichols
- Department of Biochemistry, School of Medical Sciences, University of Bristol, UK
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37
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Kelly SM, Duncan D, Price NC. Unfolding and refolding of the NAD(+)-dependent isocitrate dehydrogenase from yeast. Int J Biol Macromol 1993; 15:75-9. [PMID: 8485106 DOI: 10.1016/0141-8130(93)90001-3] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
The unfolding of the NAD(+)-dependent isocitrate dehydrogenase from yeast in guanidinium chloride (GdnHCl) has been monitored by changes in c.d. and fluorescence. Major structural changes occur over the range of GdnHCl concentrations from 0.5 to 1.5 M, although loss of catalytic activity is complete at 0.3 M. After incubation in GdnHCl, activity can be regained on dilution; however, the extent of this regain is dependent on the initial concentration of GdnHCl and is very small at a concentration of 2 M or above. Under these conditions there is only limited regain of the secondary and tertiary structure of the enzyme. Considerably more structure and activity can be regained if the concentration of GdnHCl is lowered by dialysis. The implications of these results for the folding and assembly of the enzyme are discussed.
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Affiliation(s)
- S M Kelly
- Department of Biological and Molecular Sciences, University of Stirling, Scotland, UK
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Cloning and characterization of the gene encoding the IDH1 subunit of NAD(+)-dependent isocitrate dehydrogenase from Saccharomyces cerevisiae. J Biol Chem 1992. [DOI: 10.1016/s0021-9258(18)42019-4] [Citation(s) in RCA: 72] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
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NAD(+)-dependent isocitrate dehydrogenase. Cloning, nucleotide sequence, and disruption of the IDH2 gene from Saccharomyces cerevisiae. J Biol Chem 1991. [DOI: 10.1016/s0021-9258(18)54554-3] [Citation(s) in RCA: 100] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
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Keys DA, McAlister-Henn L. Subunit structure, expression, and function of NAD(H)-specific isocitrate dehydrogenase in Saccharomyces cerevisiae. J Bacteriol 1990; 172:4280-7. [PMID: 2198251 PMCID: PMC213252 DOI: 10.1128/jb.172.8.4280-4287.1990] [Citation(s) in RCA: 85] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Mitochondrial NAD(H)-specific isocitrate dehydrogenase was purified from Saccharomyces cerevisiae for analyses of subunit structure and expression. Two subunits of the enzyme with different molecular weights (39,000 and 40,000) and slightly different isoelectric points were resolved by denaturing electrophoretic techniques. Sequence analysis of the purified subunits showed that the polypeptides have different amino termini. By using an antiserum to the native enzyme prepared in rabbits, subunit-specific immunoglobulin G fractions were obtained by affinity purification, indicating that the subunits are also immunochemically distinct. The levels of NAD(H)-specific isocitrate dehydrogenase activity and immunoreactivity were found to correlate closely with those of a second tricarboxylic acid cycle enzyme, malate dehydrogenase, in yeast cells grown under a variety of conditions. S. cerevisiae mutants with defects in NAD(H)-specific isocitrate dehydrogenase were identified by screening a collection of yeast mutants with acetate-negative growth phenotypes. Immunochemical assays were used to demonstrate that one mutant strain lacks the 40,000-molecular-weight subunit (IDH1) and that a second strain lacks the 39,000-molecular-weight subunit (IDH2). Mitochondria isolated from the IDH1 and IDH2 mutants exhibited a markedly reduced capacity for utilization of either isocitrate or citrate for respiratory O2 consumption. This confirms an essential role for NAD(H)-specific isocitrate dehydrogenase in oxidative functions in the tricarboxylic acid cycle.
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Affiliation(s)
- D A Keys
- Department of Biological Chemistry, College of Medicine, University of California, Irvine 92717
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Gabriel JL, Plaut GW. Structural requirements for the binding of AMP to the allosteric site of NAD-specific isocitrate dehydrogenase from bakers' yeast. Biochemistry 1990; 29:3528-35. [PMID: 2162196 DOI: 10.1021/bi00466a016] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
The specificity of yeast NAD-specific isocitrate dehydrogenase for the structures of the allosteric effector 5'-AMP was examined with analogues modified in the purine ring, pentosyl group, and 5'-phosphate group. An unsubstituted 6-amino group was essential for activation as was the phosphoryl group at the 5'-position. Activity was retained when an oxygen function of the 5'-phosphoryl was replaced by sulfur (Murry & Atkinson, 1968) or by nitrogen (phosphoramidates). 2-NH2-AMP, 2-azido-AMP, and 8-NH2-AMP were active; 8-azido-AMP and 8-Br-AMP were inactive. The configuration or nature of substituents about carbons 2' and 3' of the pentosyl portion of AMP was not critical for allosteric activation since AMP analogues containing, e.g., 2',3'-dideoxyribose or the bulky 2',3'-O-(2,4,6-trinitrocyclo-hexadienylidene) substituent (TNP-AMP) were active. TNP-AMP was bound to the enzyme with fluorescence enhancement and had an S0.5 for activation similar to the S0.5 for AMP. Positive effector activity was decreased when the pentosyl moiety of 5'-AMP was replaced by the six-membered nitrogen-containing morpholine group, indicating that the pentosyl group may be critical as a spacer for the proper geometry of binding to enzyme at the 6-amino and 5'-phosphoryl groups of 5'-AMP. A comparison of molecular models of 5'-AMP with 8,5'-cycloAMP suggests that the species of 5'-AMP required for binding to the enzyme contains the purine and ribose moieties in an anti conformation and positioning of the 5'-phosphate trans with respect to carbon 4'.(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- J L Gabriel
- Temple University School of Medicine, Philadelphia, Pennsylvania 19140
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Abstract
The activity of crude and pure enzyme preparations as well as the molecular weight of these enzymes were obtained from the literature for several organisms. From these data enzyme concentrations were calculated and compared to the concentration(s) of their substrates in the same organism. The data are expressed as molar ratios of metabolite concentration to enzyme site concentration. Of the 140 ratios calculated, 88% were one or greater, indicating that in general substrates exceed their cognate enzyme concentrations. Of the 17 cases where enzyme exceeds metabolite concentration, 16 were in glycolysis. The data in general justify the use of enzyme kinetic mechanisms determined in vitro in the construction of dynamic models which simulate in vivo metabolism.
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Affiliation(s)
- K R Albe
- Microbiology Department, University of Montana, Missoula 59812
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Evans CT, Scragg AH, Ratledge C. Regulation of citrate efflux from mitochondria of oleaginous and non-oleaginous yeasts by adenine nucleotides. EUROPEAN JOURNAL OF BIOCHEMISTRY 1983; 132:609-15. [PMID: 6682758 DOI: 10.1111/j.1432-1033.1983.tb07407.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
The regulation of mitochondrial citrate metabolism has been investigated in oleaginous and non-oleaginous yeasts to ascertain its importance in controlling the rate of citrate efflux from mitochondria. The following observations were made: 1. Citrate efflux from mitochondria of the oleaginous yeast Candida curvata D, in the presence of L-malate and pyruvate, was stimulated by adding ATP and reduced by AMP. In the non-oleaginous yeast, Candida utilis 359, there was very little stimulation of citrate efflux by ATP but it was reduced by AMP. These effects appeared to be generalized as similar results were obtained in an examination of eight further yeasts (seven oleaginous and one non-oleaginous). 2. The effects of ATP and AMP were not observed in mitochondria whose metabolism had been inhibited by antimycin A and rotenone indicating the direct regulation of the citrate translocase was not involved. 3. In C. curvata D, ATP increased the total mitochondrial citrate content and reduced that of 2-oxoglutarate whereas AMP had the reverse effect. In C. utilis 359, AMP had a similar effect but that of ATP was much smaller. 4. To explain these observations the mitochondrial NAD+-dependent isocitrate dehydrogenase was studied in a number of yeasts. The enzyme from oleaginous yeasts had a requirement for AMP for activity and was inhibited by ATP. In non-oleaginous yeasts the enzyme was active in the absence of AMP and increased in activity as the isocitrate concentration increased. 5. The enzyme in C. curvata D was constantly more sensitive to increasing energy charge than that of the non-oleaginous yeast. These results indicate that the supply of citrate (and hence acetyl-CoA) to the cytosol is controlled by the activity of the intramitochondrial NAD+-dependent isocitrate dehydrogenase which in turn is regulated by adenine nucleotides. The sensitivity of this enzyme to the ATP/AMP ratio during lipogenesis is therefore an important control in the accumulation of lipid by yeasts.
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Ehrlich R, Colman R. Binding of ligands to half of subunits of NAD-dependent isocitrate dehydrogenase from pig heart. Binding of manganous ion, isocitrate, ADP and NAD. J Biol Chem 1981. [DOI: 10.1016/s0021-9258(19)69960-6] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
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Chemical characterization of distinct subunits of pig heart DPN-specific isocitrate dehydrogenase. J Biol Chem 1980. [DOI: 10.1016/s0021-9258(18)43581-8] [Citation(s) in RCA: 81] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
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47
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Mitsushima K, Shinmyo A, Enatsu T. Control of citrate and 2-oxoglutarate formation in Candida lipolytica mitochondria by adenine nucleotides. BIOCHIMICA ET BIOPHYSICA ACTA 1978; 538:481-92. [PMID: 626752 DOI: 10.1016/0304-4165(78)90409-9] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
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Ramachandran N, Colman RF. Evidence for the presence of two nonidentical subunits in NAD-dependent isocitrate dehydrogenase of pig heart. Proc Natl Acad Sci U S A 1978; 75:252-5. [PMID: 203934 PMCID: PMC411224 DOI: 10.1073/pnas.75.1.252] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
The NAD-dependent isocitrate dehydrogenase [threo-D(S)-isocitrate:NAD(+) oxidoreductase (decarboxylating); EC 1.1.1.41] from pig heart is a multisubunit enzyme with a molecular weight of approximately 340,000. Electrophoresis of the enzyme in 10% polyacrylamide gels containing sodium dodecyl sulfate reveals two discrete bands with molecular weights of 41,000 and 39,000. The two bands exhibit approximately equal intensity when stained with Coomassie Blue, Amido Black, and Bromophenol Blue, suggesting that these polypeptide chains are present in equimolar quantities in the native enzyme. The same two-band pattern is observed when the sulfhydryl groups of the enzyme are blocked by alkylation with iodoacetate prior to electrophoresis, indicating that sulfhydryl oxidation is not responsible for the observed heterogeneity. Each of the subunits appears as a single band when eluted from the gel and again subjected to electrophoresis under the same conditions. Isocitrate dehydrogenase contains a total of 41 lysine and arginine residues per average subunit of 40,000 daltons. The observation of approximately 80 peptides upon paper chromatography and high voltage electrophoresis of tryptic digests of the enzyme is consistent with the existence of two distinct polypeptide chains. Dansylation yields two NH(2)-terminal amino acid derivatives: dansyl-phenylalanine and dansyl-alanine. It is concluded that the NAD-specific isocitrate dehydrogenase is composed of equal numbers of two nonidentical subunits.
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49
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Morris CA, Weber MM. Purification and properties of a soluble nicotinamide adenine dinucleotide-linked isocitrate dehydrogenase from Crithidia fasciculata. J Biol Chem 1975. [DOI: 10.1016/s0021-9258(19)41656-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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