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Chen X, Ding J. Molecular insights into the catalysis and regulation of mammalian NAD-dependent isocitrate dehydrogenases. Curr Opin Struct Biol 2023; 82:102672. [PMID: 37542909 DOI: 10.1016/j.sbi.2023.102672] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2023] [Revised: 07/08/2023] [Accepted: 07/10/2023] [Indexed: 08/07/2023]
Abstract
Eukaryotic NAD-dependent isocitrate dehydrogenases (NAD-IDHs) are mitochondria-localized enzymes which catalyze the oxidative decarboxylation of isocitrate to α-ketoglutarate using NAD as a cofactor. In mammals, NAD-IDHs (or IDH3) consist of three types of subunits (α, β, and γ), and exist as (α2βγ)2 heterooctamer. Mammalian NAD-IDHs are regulated allosterically and/or competitively by a diversity of metabolites including citrate, ADP, ATP, NADH, and NADPH, which are associated with cellular metabolite flux, energy demands, and redox status. Proper assembly of the component subunits is essential for the catalysis and regulation of the enzymes. Recently, crystal structures of human IDH3 have been solved in apo form and in complex with various ligands, revealing the molecular mechanisms for the assembly, catalysis, and regulation of the enzyme.
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Affiliation(s)
- Xingchen Chen
- State Key Laboratory of Molecular Biology, Shanghai Institute of Biochemistry and Cell Biology, Center for Excellence in Molecular Cell Science, Chinese Academy of Sciences, 320 Yueyang Road, Shanghai 200031, China
| | - Jianping Ding
- State Key Laboratory of Molecular Biology, Shanghai Institute of Biochemistry and Cell Biology, Center for Excellence in Molecular Cell Science, Chinese Academy of Sciences, 320 Yueyang Road, Shanghai 200031, China; School of Life Science and Technology, ShanghaiTech University, 393 Huaxia Zhong Road, Shanghai 201210, China.
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2
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Structures of a constitutively active mutant of human IDH3 reveal new insights into the mechanisms of allosteric activation and the catalytic reaction. J Biol Chem 2022; 298:102695. [PMID: 36375638 PMCID: PMC9731866 DOI: 10.1016/j.jbc.2022.102695] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2022] [Revised: 10/28/2022] [Accepted: 11/09/2022] [Indexed: 11/13/2022] Open
Abstract
Human NAD-dependent isocitrate dehydrogenase or IDH3 (HsIDH3) catalyzes the decarboxylation of isocitrate into α-ketoglutarate in the tricarboxylic acid cycle. It consists of three types of subunits (α, β, and γ) and exists and functions as the (αβαγ)2 heterooctamer. HsIDH3 is regulated allosterically and/or competitively by numerous metabolites including CIT, ADP, ATP, and NADH. Our previous studies have revealed the molecular basis for the activity and regulation of the αβ and αγ heterodimers. However, the molecular mechanism for the allosteric activation of the HsIDH3 holoenzyme remains elusive. In this work, we report the crystal structures of the αβ and αγ heterodimers and the (αβαγ)2 heterooctamer containing an α-Q139A mutation in the clasp domain, which renders all the heterodimers and the heterooctamer constitutively active in the absence of activators. Our structural analysis shows that the α-Q139A mutation alters the hydrogen-bonding network at the heterodimer-heterodimer interface in a manner similar to that in the activator-bound αγ heterodimer. This alteration not only stabilizes the active sites of both αQ139Aβ and αQ139Aγ heterodimers in active conformations but also induces conformational changes of the pseudo-allosteric site of the αQ139Aβ heterodimer enabling it to bind activators. In addition, the αQ139AICT+Ca+NADβNAD structure presents the first pseudo-Michaelis complex of HsIDH3, which allows us to identify the key residues involved in the binding of cofactor, substrate, and metal ion. Our structural and biochemical data together reveal new insights into the molecular mechanisms for allosteric regulation and the catalytic reaction of HsIDH3.
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3
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Yang Q, Guo X, Liu Y, Jiang H. Biocatalytic C-C Bond Formation for One Carbon Resource Utilization. Int J Mol Sci 2021; 22:ijms22041890. [PMID: 33672882 PMCID: PMC7918591 DOI: 10.3390/ijms22041890] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2020] [Revised: 01/31/2021] [Accepted: 02/05/2021] [Indexed: 12/22/2022] Open
Abstract
The carbon-carbon bond formation has always been one of the most important reactions in C1 resource utilization. Compared to traditional organic synthesis methods, biocatalytic C-C bond formation offers a green and potent alternative for C1 transformation. In recent years, with the development of synthetic biology, more and more carboxylases and C-C ligases have been mined and designed for the C1 transformation in vitro and C1 assimilation in vivo. This article presents an overview of C-C bond formation in biocatalytic C1 resource utilization is first provided. Sets of newly mined and designed carboxylases and ligases capable of catalyzing C-C bond formation for the transformation of CO2, formaldehyde, CO, and formate are then reviewed, and their catalytic mechanisms are discussed. Finally, the current advances and the future perspectives for the development of catalysts for C1 resource utilization are provided.
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Affiliation(s)
- Qiaoyu Yang
- Key Laboratory of Systems Microbial Biotechnology, Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, Tianjin 300308, China; (Q.Y.); (X.G.)
- National Technology Innovation Center of Synthetic Biology, Tianjin 300308, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Xiaoxian Guo
- Key Laboratory of Systems Microbial Biotechnology, Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, Tianjin 300308, China; (Q.Y.); (X.G.)
- National Technology Innovation Center of Synthetic Biology, Tianjin 300308, China
| | - Yuwan Liu
- Key Laboratory of Systems Microbial Biotechnology, Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, Tianjin 300308, China; (Q.Y.); (X.G.)
- National Technology Innovation Center of Synthetic Biology, Tianjin 300308, China
- Correspondence: (Y.L.); (H.J.)
| | - Huifeng Jiang
- Key Laboratory of Systems Microbial Biotechnology, Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, Tianjin 300308, China; (Q.Y.); (X.G.)
- National Technology Innovation Center of Synthetic Biology, Tianjin 300308, China
- Correspondence: (Y.L.); (H.J.)
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4
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Sun P, Liu Y, Ma T, Ding J. Structure and allosteric regulation of human NAD-dependent isocitrate dehydrogenase. Cell Discov 2020; 6:94. [PMID: 33349631 PMCID: PMC7752914 DOI: 10.1038/s41421-020-00220-7] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2020] [Revised: 09/24/2020] [Accepted: 09/25/2020] [Indexed: 11/09/2022] Open
Abstract
Human NAD-dependent isocitrate dehydrogenase or HsIDH3 catalyzes the decarboxylation of isocitrate into α-ketoglutarate in the TCA cycle. HsIDH3 exists and functions as a heterooctamer composed of the αβ and αγ heterodimers, and is regulated allosterically and/or competitively by numerous metabolites including CIT, ADP, ATP, and NADH. In this work, we report the crystal structure of HsIDH3 containing a β mutant in apo form. In the HsIDH3 structure, the αβ and αγ heterodimers form the α2βγ heterotetramer via their clasp domains, and two α2βγ heterotetramers form the (α2βγ)2 heterooctamer through insertion of the N-terminus of the γ subunit of one heterotetramer into the back cleft of the β subunit of the other heterotetramer. The functional roles of the key residues at the allosteric site, the pseudo allosteric site, the heterodimer and heterodimer-heterodimer interfaces, and the N-terminal of the γ subunit are validated by mutagenesis and kinetic studies. Our structural and biochemical data together demonstrate that the allosteric site plays an important role but the pseudo allosteric site plays no role in the allosteric activation of the enzyme; the activation signal from the allosteric site is transmitted to the active sites of both αβ and αγ heterodimers via the clasp domains; and the N-terminal of the γ subunit plays a critical role in the formation of the heterooctamer to ensure the optimal activity of the enzyme. These findings reveal the molecular mechanism of the assembly and allosteric regulation of HsIDH3.
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Affiliation(s)
- Pengkai Sun
- State Key Laboratory of Molecular Biology, Shanghai Institute of Biochemistry and Cell Biology, Center for Excellence in Molecular Cell Science, University of Chinese Academy of Sciences, Chinese Academy of Sciences, 320 Yueyang Road, Shanghai 200031, China
| | - Yan Liu
- School of Life Science and Technology, ShanghaiTech University, 393 Huaxia Zhong Road, Shanghai 201210, China
| | - Tengfei Ma
- State Key Laboratory of Molecular Biology, Shanghai Institute of Biochemistry and Cell Biology, Center for Excellence in Molecular Cell Science, University of Chinese Academy of Sciences, Chinese Academy of Sciences, 320 Yueyang Road, Shanghai 200031, China
| | - Jianping Ding
- State Key Laboratory of Molecular Biology, Shanghai Institute of Biochemistry and Cell Biology, Center for Excellence in Molecular Cell Science, University of Chinese Academy of Sciences, Chinese Academy of Sciences, 320 Yueyang Road, Shanghai 200031, China. .,School of Life Science and Technology, ShanghaiTech University, 393 Huaxia Zhong Road, Shanghai 201210, China. .,School of Life Science, Hangzhou Institute for Advanced Study, University of Chinese Academy of Sciences, 1 Xiangshan Road, Hangzhou, Zhejiang 310024, China.
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5
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May JL, Kouri FM, Hurley LA, Liu J, Tommasini-Ghelfi S, Ji Y, Gao P, Calvert AE, Lee A, Chandel NS, Davuluri RV, Horbinski CM, Locasale JW, Stegh AH. IDH3α regulates one-carbon metabolism in glioblastoma. SCIENCE ADVANCES 2019; 5:eaat0456. [PMID: 30613765 PMCID: PMC6314828 DOI: 10.1126/sciadv.aat0456] [Citation(s) in RCA: 51] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/18/2018] [Accepted: 11/26/2018] [Indexed: 05/17/2023]
Abstract
Mutation or transcriptional up-regulation of isocitrate dehydrogenases 1 and 2 (IDH1 and IDH2) promotes cancer progression through metabolic reprogramming and epigenetic deregulation of gene expression. Here, we demonstrate that IDH3α, a subunit of the IDH3 heterotetramer, is elevated in glioblastoma (GBM) patient samples compared to normal brain tissue and promotes GBM progression in orthotopic glioma mouse models. IDH3α loss of function reduces tricarboxylic acid (TCA) cycle turnover and inhibits oxidative phosphorylation. In addition to its impact on mitochondrial energy metabolism, IDH3α binds to cytosolic serine hydroxymethyltransferase (cSHMT). This interaction enhances nucleotide availability during DNA replication, while the absence of IDH3α promotes methionine cycle activity, S-adenosyl methionine generation, and DNA methylation. Thus, the regulation of one-carbon metabolism via an IDH3α-cSHMT signaling axis represents a novel mechanism of metabolic adaptation in GBM.
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Affiliation(s)
- Jasmine L. May
- Ken and Ruth Davee Department of Neurology, The Northwestern Brain Tumor Institute, The Robert H. Lurie Comprehensive Cancer Center, Northwestern University, 303 East Superior, Chicago, IL 60611, USA
- International Institute for Nanotechnology, Northwestern University, 2145 Sheridan Road, Evanston, IL 60208, USA
| | - Fotini M. Kouri
- Ken and Ruth Davee Department of Neurology, The Northwestern Brain Tumor Institute, The Robert H. Lurie Comprehensive Cancer Center, Northwestern University, 303 East Superior, Chicago, IL 60611, USA
- International Institute for Nanotechnology, Northwestern University, 2145 Sheridan Road, Evanston, IL 60208, USA
| | - Lisa A. Hurley
- Ken and Ruth Davee Department of Neurology, The Northwestern Brain Tumor Institute, The Robert H. Lurie Comprehensive Cancer Center, Northwestern University, 303 East Superior, Chicago, IL 60611, USA
- International Institute for Nanotechnology, Northwestern University, 2145 Sheridan Road, Evanston, IL 60208, USA
| | - Juan Liu
- Department of Pharmacology and Cancer Biology, Duke University School of Medicine, Durham, NC 27710, USA
| | - Serena Tommasini-Ghelfi
- Ken and Ruth Davee Department of Neurology, The Northwestern Brain Tumor Institute, The Robert H. Lurie Comprehensive Cancer Center, Northwestern University, 303 East Superior, Chicago, IL 60611, USA
- International Institute for Nanotechnology, Northwestern University, 2145 Sheridan Road, Evanston, IL 60208, USA
| | - Yanrong Ji
- Preventive Medicine, Health and Biomedical Informatics, Feinberg School of Medicine, The Robert H. Lurie Comprehensive Cancer Center, Northwestern University, Chicago, IL 60611, USA
| | - Peng Gao
- Metabolomics Core Facility of Robert H. Lurie Comprehensive Cancer Center, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, USA
| | - Andrea E. Calvert
- Ken and Ruth Davee Department of Neurology, The Northwestern Brain Tumor Institute, The Robert H. Lurie Comprehensive Cancer Center, Northwestern University, 303 East Superior, Chicago, IL 60611, USA
- International Institute for Nanotechnology, Northwestern University, 2145 Sheridan Road, Evanston, IL 60208, USA
| | - Andrew Lee
- Department of Chemical and Biological Engineering, Northwestern University, Evanston, IL 60208, USA
| | - Navdeep S. Chandel
- Department of Medicine, Northwestern University Feinberg School of Medicine, Chicago, IL 60615, USA
| | - Ramana V. Davuluri
- Preventive Medicine, Health and Biomedical Informatics, Feinberg School of Medicine, The Robert H. Lurie Comprehensive Cancer Center, Northwestern University, Chicago, IL 60611, USA
| | - Craig M. Horbinski
- Department of Neurological Surgery, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, USA
- Department of Pathology, Northwestern University Feinberg School of Medicine, Chicago, IL 60615, USA
| | - Jason W. Locasale
- Department of Pharmacology and Cancer Biology, Duke University School of Medicine, Durham, NC 27710, USA
| | - Alexander H. Stegh
- Ken and Ruth Davee Department of Neurology, The Northwestern Brain Tumor Institute, The Robert H. Lurie Comprehensive Cancer Center, Northwestern University, 303 East Superior, Chicago, IL 60611, USA
- International Institute for Nanotechnology, Northwestern University, 2145 Sheridan Road, Evanston, IL 60208, USA
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Comparative Proteomic Analysis of Rana chensinensis Oviduct. Molecules 2018; 23:molecules23061384. [PMID: 29890619 PMCID: PMC6099995 DOI: 10.3390/molecules23061384] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2018] [Revised: 05/31/2018] [Accepted: 06/05/2018] [Indexed: 12/31/2022] Open
Abstract
As one of most important traditional Chinese medicine resources, the oviduct of female Rana chensinensis (Chinese brown frog) was widely used in the treatment of asthenia after sickness or delivery, deficiency in vigor, palpitation, and insomnia. Unlike other vertebrates, the oviduct of Rana chensinensis oviduct significantly expands during prehibernation, in contrast to the breeding period. To explain this phenomenon at the molecular level, the protein expression profiles of Rana chensinensis oviduct during the breeding period and prehibernation were observed using isobaric tags for relative and absolute quantitation (iTRAQ) technique. Then, all identified proteins were used to obtain gene ontology (GO) annotation. Ultimately, KEGG (Kyoto Encyclopedia of Genes and Genomes) enrichment analysis was performed to predict the pathway on differentially expressed proteins (DEPs). A total of 4479 proteins were identified, and 312 of them presented different expression profiling between prehibernation and breeding period. Compared with prehibernation group, 86 proteins were upregulated, and 226 proteins were downregulated in breeding period. After KEGG enrichment analysis, 163 DEPs were involved in 6 pathways, which were lysosome, RNA transport, glycosaminoglycan degradation, extracellular matrix (ECM)–receptor interaction, metabolic pathways and focal adhesion. This is the first report on the protein profiling of Rana chensinensis oviduct during the breeding period and prehibernation. Results show that this distinctive physiological phenomenon of Rana chensinensis oviduct was mainly involved in ECM–receptor interaction, metabolic pathways, and focal adhesion.
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7
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Insights into the inhibitory mechanisms of NADH on the αγ heterodimer of human NAD-dependent isocitrate dehydrogenase. Sci Rep 2018; 8:3146. [PMID: 29453450 PMCID: PMC5816668 DOI: 10.1038/s41598-018-21584-7] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2017] [Accepted: 02/07/2018] [Indexed: 11/09/2022] Open
Abstract
Human NAD-dependent isocitrate dehydrogenase (NAD-IDH) catalyzes the oxidative decarboxylation of isocitrate in the citric acid cycle. In the α2βγ heterotetramer of NAD-IDH, the γ subunit plays the regulatory role and the β subunit the structural role. Previous biochemical data have shown that mammalian NAD-IDHs can be inhibited by NADH; however, the molecular mechanism is unclear. In this work, we show that the αβ, αγ and α2βγ enzymes of human NAD-IDH can be inhibited by NADH, and further determine the crystal structure of the αγ heterodimer bound with an Mg2+ and an NADH at the active site and an NADH at the allosteric site, which resembles that of the inactive αMgγ heterodimer. The NADH at the active site occupies the binding site for NAD+ and prevents the binding of the cofactor. The NADH at the allosteric site occupies the binding sites for ADP and citrate and blocks the binding of the activators. The biochemical data confirm that the NADH binding competes with the binding of NAD+ and the binding of citrate and ADP, and the two effects together contribute to the NADH inhibition on the activity. These findings provide insights into the inhibitory mechanisms of the αγ heterodimer by NADH.
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8
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Kim YR, Kim KH, Lee S, Oh SK, Park JW, Lee KY, Baek JI, Kim UK. Expression patterns of members of the isocitrate dehydrogenase gene family in murine inner ear. Biotech Histochem 2017; 92:536-544. [PMID: 28925723 DOI: 10.1080/10520295.2017.1367034] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022] Open
Abstract
Age-related hearing loss (ARHL) is characterized by an age-dependent decline of auditory function characterized by with loss of sensory hair cells, spiral ganglion neurons, and stria vascularis (SV) cells in the cochlea of the inner ear. Aging and age-related diseases result from accumulated oxidative damage caused by reactive oxygen species (ROS) generated by mitochondria. The isocitrate dehydrogenase (IDH) family includes three enzymes in human cells: IDH1, IDH2, and IDH3. Although all three enzymes catalyze the same enzymatic reaction, that is, oxidative decarboxylation of isocitrate to produce α-ketoglutarate, each IDH enzyme has unique features. We identified and characterized IDH expression in the cochlea and vestibule of the murine inner ear. We examined the mRNA expression levels of Idh family members in the cochlea and vestibule using reverse transcription-PCR (RT-PCR) and detected expression of IDH family members in both tissues. We also used immunohistochemistry to localize IDH family members within the cochlea and vestibule of the adult mouse inner ear. IDH1 was detected throughout the cochlea. IDH2 was expressed specifically in the hair cells, spiral ganglion, and stria vascularis. IDH3α was found in the cell bodies of neurons of the spiral ganglion, the stria vascularis, and in types II, IV, and V cells of the spiral ligament in a pattern that resembled the location of the Na+, K+-ATPase ion channel. We postulate that the IDH family participates in transporting K+ ions in the cochlea. In the vestibule, all IDH family members were detected in both hair cells and the vestibular ganglion. We hypothesize that IDH1, IDH2, and IDH3 function to protect proteins in the inner ear from oxidative stress during K+ recycling.
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Affiliation(s)
- Y-R Kim
- a Department of Biology, College of Natural Sciences , Kyungpook National University.,b School of Life Sciences, KNU Creative BioResearch Group (BK21 plus project) , Kyungpook National University
| | - K-H Kim
- a Department of Biology, College of Natural Sciences , Kyungpook National University.,b School of Life Sciences, KNU Creative BioResearch Group (BK21 plus project) , Kyungpook National University
| | - S Lee
- a Department of Biology, College of Natural Sciences , Kyungpook National University.,b School of Life Sciences, KNU Creative BioResearch Group (BK21 plus project) , Kyungpook National University
| | - S-K Oh
- c Laboratory Animal Center, Daegu-Gyeonbuk Medical Innovation Foundation
| | - J-W Park
- a Department of Biology, College of Natural Sciences , Kyungpook National University.,b School of Life Sciences, KNU Creative BioResearch Group (BK21 plus project) , Kyungpook National University
| | - K-Y Lee
- d Department of Otorhinolaryngology-Head and Neck Surgery , Kyungpook National University Hospital, Kyungpook National University School of Medicine
| | - J-I Baek
- e Department of Aroma Applied Industry , College of Herbal Bio-industry, Daegu Haany University , Daegu , Republic of Korea
| | - U-K Kim
- a Department of Biology, College of Natural Sciences , Kyungpook National University.,b School of Life Sciences, KNU Creative BioResearch Group (BK21 plus project) , Kyungpook National University
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The β and γ subunits play distinct functional roles in the α 2βγ heterotetramer of human NAD-dependent isocitrate dehydrogenase. Sci Rep 2017; 7:41882. [PMID: 28139779 PMCID: PMC5282582 DOI: 10.1038/srep41882] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2016] [Accepted: 12/28/2016] [Indexed: 01/24/2023] Open
Abstract
Human NAD-dependent isocitrate dehydrogenase existing as the α2βγ heterotetramer, catalyzes the decarboxylation of isocitrate into α-ketoglutarate in the Krebs cycle, and is allosterically regulated by citrate, ADP and ATP. To explore the functional roles of the regulatory β and γ subunits, we systematically characterized the enzymatic properties of the holoenzyme and the composing αβ and αγ heterodimers in the absence and presence of regulators. The biochemical and mutagenesis data show that αβ and αγ alone have considerable basal activity but the full activity of α2βγ requires the assembly and cooperative function of both heterodimers. α2βγ and αγ can be activated by citrate or/and ADP, whereas αβ cannot. The binding of citrate or/and ADP decreases the S0.5,isocitrate and thus enhances the catalytic efficiencies of the enzymes, and the two activators can act independently or synergistically. Moreover, ATP can activate α2βγ and αγ at low concentration and inhibit the enzymes at high concentration, but has only inhibitory effect on αβ. Furthermore, the allosteric activation of α2βγ is through the γ subunit not the β subunit. These results demonstrate that the γ subunit plays regulatory role to activate the holoenzyme, and the β subunit the structural role to facilitate the assembly of the holoenzyme.
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10
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Ma T, Peng Y, Huang W, Ding J. Molecular mechanism of the allosteric regulation of the αγ heterodimer of human NAD-dependent isocitrate dehydrogenase. Sci Rep 2017; 7:40921. [PMID: 28098230 PMCID: PMC5241874 DOI: 10.1038/srep40921] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2016] [Accepted: 12/13/2016] [Indexed: 11/12/2022] Open
Abstract
Human NAD-dependent isocitrate dehydrogenase catalyzes the decarboxylation of isocitrate (ICT) into α-ketoglutarate in the Krebs cycle. It exists as the α2βγ heterotetramer composed of the αβ and αγ heterodimers. Previously, we have demonstrated biochemically that the α2βγ heterotetramer and αγ heterodimer can be allosterically activated by citrate (CIT) and ADP. In this work, we report the crystal structures of the αγ heterodimer with the γ subunit bound without or with different activators. Structural analyses show that CIT, ADP and Mg2+ bind adjacent to each other at the allosteric site. The CIT binding induces conformational changes at the allosteric site, which are transmitted to the active site through the heterodimer interface, leading to stabilization of the ICT binding at the active site and thus activation of the enzyme. The ADP binding induces no further conformational changes but enhances the CIT binding through Mg2+-mediated interactions, yielding a synergistic activation effect. ICT can also bind to the CIT-binding subsite, which induces similar conformational changes but exhibits a weaker activation effect. The functional roles of the key residues are verified by mutagenesis, kinetic and structural studies. Our structural and functional data together reveal the molecular mechanism of the allosteric regulation of the αγ heterodimer.
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Affiliation(s)
- Tengfei Ma
- National Center for Protein Science Shanghai, State Key Laboratory of Molecular Biology, Center for Excellence in Molecular Cell Science, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, 320 Yueyang Road, Shanghai 200031, China
| | - Yingjie Peng
- National Center for Protein Science Shanghai, State Key Laboratory of Molecular Biology, Center for Excellence in Molecular Cell Science, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, 320 Yueyang Road, Shanghai 200031, China
| | - Wei Huang
- National Center for Protein Science Shanghai, State Key Laboratory of Molecular Biology, Center for Excellence in Molecular Cell Science, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, 320 Yueyang Road, Shanghai 200031, China
| | - Jianping Ding
- National Center for Protein Science Shanghai, State Key Laboratory of Molecular Biology, Center for Excellence in Molecular Cell Science, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, 320 Yueyang Road, Shanghai 200031, China
- School of Life Science and Technology, ShanghaiTech University, 100 Haike Road, Shanghai 201210, China
- Shanghai Science Research Center, Chinese Academy of Sciences, 333 Haike Road, Shanghai 201210, China
- Collaborative Innovation Center for Genetics and Development, Fudan University, 2005 Songhu Road, Shanghai 200438, China
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11
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Fattal-Valevski A, Eliyahu H, Fraenkel NID, Elmaliach G, Hausman-Kedem M, Shaag A, Mandel D, Pines O, Elpeleg O. Homozygous mutation, p.Pro304His, in IDH3A, encoding isocitrate dehydrogenase subunit is associated with severe encephalopathy in infancy. Neurogenetics 2017; 18:57-61. [PMID: 28058510 DOI: 10.1007/s10048-016-0507-z] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2016] [Accepted: 12/20/2016] [Indexed: 10/20/2022]
Abstract
Mitochondrial encephalopathies are a heterogeneous group of disorders which generally carries a grave prognosis. Using exome sequencing, we identified a homozygous mutation, Pro-304-His in the IDH3A gene, in a patient suffering from infantile encephalopathy with peripheral and autonomic nervous system involvement. Mammalian isocitrate dehydrogenase (IDH) 3 is a heterotetramer of 2alfa, 1beta, and 1gamma subunits, and IDH3A encodes the alfa subunit of the mitochondrial NAD+-dependent IDH. Here we show that in contrast to wild-type human IDH3A, the human IDH3A which harbor the p.Pro304His mutation does not complement the yeast Δidh1/Δidh2 growth defect on ethanol-acetate. We therefore propose that homozygosity for the p.Pro304His mutation is deleterious for mitochondrial NAD+-specific IDH3A activity in human. IDH3A now joins the list of TCA cycle-related proteins, which includes ACO2, DLD, SLC25A19, FH, and succinate dehydrogenase subunits, all associated with neurological disorders.
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Affiliation(s)
- Aviva Fattal-Valevski
- Pediatric Neurology Unit, Dana-Dwek Children's Hospital, Tel Aviv Medical Center & Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Hila Eliyahu
- Department of Microbiology Molecular Genetics, IMRIC, Faculty of Medicine, Hebrew University of Jerusalem, Jerusalem, Israel
| | - NItai D Fraenkel
- Department of Respiratory Rehabilitation, Alyn Hospital, Jerusalem, Israel
| | - Ganit Elmaliach
- Department of Microbiology Molecular Genetics, IMRIC, Faculty of Medicine, Hebrew University of Jerusalem, Jerusalem, Israel
| | - Moran Hausman-Kedem
- Pediatric Neurology Unit, Dana-Dwek Children's Hospital, Tel Aviv Medical Center & Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Avraham Shaag
- Monique and Jacques Roboh Department of Genetic Research, Hadassah, Hebrew University Medical Center, Jerusalem, Israel
| | - Dror Mandel
- Department of Neonatology, Lis Maternity Hospital, Tel Aviv Medical Center & Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Ophry Pines
- Department of Microbiology Molecular Genetics, IMRIC, Faculty of Medicine, Hebrew University of Jerusalem, Jerusalem, Israel.
| | - Orly Elpeleg
- Monique and Jacques Roboh Department of Genetic Research, Hadassah, Hebrew University Medical Center, Jerusalem, Israel.
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12
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Wang P, Lv C, Zhu G. Novel type II and monomeric NAD+ specific isocitrate dehydrogenases: phylogenetic affinity, enzymatic characterization, and evolutionary implication. Sci Rep 2015; 5:9150. [PMID: 25775177 PMCID: PMC4360740 DOI: 10.1038/srep09150] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2014] [Accepted: 02/23/2015] [Indexed: 11/09/2022] Open
Abstract
NAD(+) use is an ancestral trait of isocitrate dehydrogenase (IDH), and the NADP(+) phenotype arose through evolution as an ancient adaptation event. However, no NAD(+)-specific IDHs have been found among type II IDHs and monomeric IDHs. In this study, novel type II homodimeric NAD-IDHs from Ostreococcus lucimarinus CCE9901 IDH (OlIDH) and Micromonas sp. RCC299 (MiIDH), and novel monomeric NAD-IDHs from Campylobacter sp. FOBRC14 IDH (CaIDH) and Campylobacter curvus (CcIDH) were reported for the first time. The homodimeric OlIDH and monomeric CaIDH were determined by size exclusion chromatography and MALDI-TOF/TOF mass spectrometry. All the four IDHs were demonstrated to be NAD(+)-specific, since OlIDH, MiIDH, CaIDH and CcIDH displayed 99-fold, 224-fold, 61-fold and 37-fold preferences for NAD(+) over NADP(+), respectively. The putative coenzyme discriminating amino acids (Asp326/Met327 in OlIDH, Leu584/Asp595 in CaIDH) were evaluated, and the coenzyme specificities of the two mutants, OlIDH R(326)H(327) and CaIDH H(584)R(595), were completely reversed from NAD(+) to NADP(+). The detailed biochemical properties, including optimal reaction pH and temperature, thermostability, and metal ion effects, of OlIDH and CaIDH were further investigated. The evolutionary connections among OlIDH, CaIDH, and all the other forms of IDHs were described and discussed thoroughly.
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Affiliation(s)
- Peng Wang
- Institute of Molecular Biology and Biotechnology, College of Life Sciences, Anhui Normal University, No.1 Beijing East Road, Wuhu 241000, Anhui, China
| | - Changqi Lv
- Institute of Molecular Biology and Biotechnology, College of Life Sciences, Anhui Normal University, No.1 Beijing East Road, Wuhu 241000, Anhui, China
| | - Guoping Zhu
- Institute of Molecular Biology and Biotechnology, College of Life Sciences, Anhui Normal University, No.1 Beijing East Road, Wuhu 241000, Anhui, China
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Tang WG, Song P, Cao ZY, Wang P, Zhu GP. A unique homodimeric NAD⁺-linked isocitrate dehydrogenase from the smallest autotrophic eukaryote Ostreococcus tauri. FASEB J 2015; 29:2462-72. [PMID: 25724193 DOI: 10.1096/fj.14-257014] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2014] [Accepted: 02/03/2015] [Indexed: 11/11/2022]
Abstract
In eukaryotes, NAD(+)-dependent isocitrate dehydrogenase (IDH) is strictly mitochondrial and is a key enzyme in the Krebs cycle. To date, all known NAD(+)-specific IDHs (NAD-IDHs) in the mitochondria are believed to be heteromeric in solution. Here, a unique homodimeric NAD-IDH from Ostreococcus tauri (OtIDH), the smallest autotrophic picoeukaryote, was unveiled. Active OtIDH has a molecular weight of ∼93 kDa with each subunit of 46.7 kDa. In the presence of Mn(2+) and Mg(2+), OtIDH displayed 42-fold and 51-fold preference for NAD(+) over NADP(+), respectively. Interestingly, OtIDH exhibited a sigmoidal kinetic behavior in response to isocitrate unlike other homodimeric homologs, and a remarkably high affinity for isocitrate (S0.5 < 10 μM) unlike other hetero-oligomeric homologs. Furthermore, its coenzyme specificity can be completely converted from NAD(+) (ancient trait) to NADP(+) (adaptive trait) by rational mutagenesis based on the evolutionary trace. Mutants D344R and D344R/M345H displayed a 15-fold and 72-fold preference for NADP(+) over NAD(+), respectively, indicating that D344 and M345 are the determinants of NAD(+) specificity. These findings also suggest that OtIDH may be an ancestral form of type II IDHs (all reported members are NADP(+)-linked enzymes) and may have evolved into NADP(+)-dependent IDH for adaptation to the increased demand of NADPH under carbon starvation.
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Affiliation(s)
- Wang-Gang Tang
- Institute of Molecular Biology and Biotechnology, College of Life Sciences, Anhui Normal University, Wuhu, China
| | - Ping Song
- Institute of Molecular Biology and Biotechnology, College of Life Sciences, Anhui Normal University, Wuhu, China
| | - Zheng-Yu Cao
- Institute of Molecular Biology and Biotechnology, College of Life Sciences, Anhui Normal University, Wuhu, China
| | - Peng Wang
- Institute of Molecular Biology and Biotechnology, College of Life Sciences, Anhui Normal University, Wuhu, China
| | - Guo-Ping Zhu
- Institute of Molecular Biology and Biotechnology, College of Life Sciences, Anhui Normal University, Wuhu, China
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14
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Song P, Wei H, Cao Z, Wang P, Zhu G. Single arginine mutation in two yeast isocitrate dehydrogenases: biochemical characterization and functional implication. PLoS One 2014; 9:e115025. [PMID: 25502799 PMCID: PMC4263744 DOI: 10.1371/journal.pone.0115025] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2014] [Accepted: 11/17/2014] [Indexed: 11/18/2022] Open
Abstract
Isocitrate dehydrogenase (IDH), a housekeeping gene, has drawn the attention of cancer experts. Mutation of the catalytic Arg132 residue of human IDH1 (HcIDH) eliminates the enzyme's wild-type isocitrate oxidation activity, but confer the mutant an ability of reducing α-ketoglutarate (α-KG) to 2-hydroxyglutarate (2-HG). To examine whether an analogous mutation in IDHs of other eukaryotes could cause similar effects, two yeast mitochondrial IDHs, Saccharomyces cerevisiae NADP+-IDH1 (ScIDH1) and Yarrowia lipolytica NADP+-IDH (YlIDH), were studied. The analogous Arg residues (Arg148 of ScIDH1 and Arg141 of YlIDH) were mutated to His. The Km values of ScIDH1 R148H and YlIDH R141H for isocitrate were determined to be 2.4-fold and 2.2-fold higher, respectively, than those of the corresponding wild-type enzymes. The catalytic efficiencies (kcat/Km) of ScIDH1 R148H and YlIDH R141H for isocitrate oxidation were drastically reduced by 227-fold and 460-fold, respectively, of those of the wild-type enzymes. As expected, both ScIDH1 R148H and YlIDH R141H acquired the neomorphic activity of catalyzing α-KG to 2-HG, and the generation of 2-HG was confirmed using gas chromatography/time of flight-mass spectrometry (GC/TOF-MS). Kinetic analysis showed that ScIDH1 R148H and YlIDH R141H displayed 5.2-fold and 3.3-fold higher affinities, respectively, for α-KG than the HcIDH R132H mutant. The catalytic efficiencies of ScIDH1 R148H and YlIDH R141H for α-KG were 5.5-fold and 4.5-fold, respectively, of that of the HcIDH R132H mutant. Since the HcIDH Arg132 mutation is associated with the tumorigenesis, this study provides fundamental information for further research on the physiological role of this IDH mutation in vivo using yeast.
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Affiliation(s)
- Ping Song
- Institute of Molecular Biology and Biotechnology, Anhui Normal University, No. 1 Beijing East Road, Wuhu, 241000, Anhui, China
| | - Huanhuan Wei
- Institute of Molecular Biology and Biotechnology, Anhui Normal University, No. 1 Beijing East Road, Wuhu, 241000, Anhui, China
| | - Zhengyu Cao
- Institute of Molecular Biology and Biotechnology, Anhui Normal University, No. 1 Beijing East Road, Wuhu, 241000, Anhui, China
| | - Peng Wang
- Institute of Molecular Biology and Biotechnology, Anhui Normal University, No. 1 Beijing East Road, Wuhu, 241000, Anhui, China
- * E-mail: (PW); (GPZ)
| | - Guoping Zhu
- Institute of Molecular Biology and Biotechnology, Anhui Normal University, No. 1 Beijing East Road, Wuhu, 241000, Anhui, China
- * E-mail: (PW); (GPZ)
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15
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Ma D, Cui L, Gao J, Yan W, Liu Y, Xu S, Wu B. Proteomic analysis of mesenchymal stem cells from normal and deep carious dental pulp. PLoS One 2014; 9:e97026. [PMID: 24809979 PMCID: PMC4014579 DOI: 10.1371/journal.pone.0097026] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2014] [Accepted: 04/14/2014] [Indexed: 12/19/2022] Open
Abstract
Dental pulp stem cells (DPSCs), precursor cells of odontoblasts, are ideal seed cells for tooth tissue engineering and regeneration. Our previous study has demonstrated that stem cells exist in dental pulp with deep caries and are called carious dental pulp stem cells (CDPSCs). The results indicated that CDPSCs had a higher proliferative and stronger osteogenic differentiation potential than DPSCs. However, the molecular mechanisms responsible for the biological differences between DPSCs and CDPSCs are poorly understood. The aim of this study was to define the molecular features of DPSCs and CDPSCs by comparing the proteomic profiles using two-dimensional fluorescence difference gel electrophoresis (2-D DIGE) in combination with matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS). Our results revealed that there were 18 protein spots differentially expressed between DPSCs and CDPSCs in a narrow pH range of 4 to 7. These differently expressed proteins are mostly involved in the regulation of cell proliferation, differentiation, cell cytoskeleton and motility. In addition, our results suggested that CDPSCs had a higher expression of antioxidative proteins that might protect CDPSCs from oxidative stress. This study explores some potential proteins responsible for the biological differences between DPSCs and CDPSCs and expands our understanding on the molecular mechanisms of mineralization of DPSCs in the formation of the dentin-pulp complex.
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Affiliation(s)
- Dandan Ma
- Department of Stomatology, Nanfang Hospital, Guangzhou, P.R. China
- College of Stomatology, Southern Medical University, Guangzhou, P.R. China
| | - Li Cui
- Department of Stomatology, Nanfang Hospital, Guangzhou, P.R. China
- College of Stomatology, Southern Medical University, Guangzhou, P.R. China
| | - Jie Gao
- Department of Stomatology, Nanfang Hospital, Guangzhou, P.R. China
- College of Stomatology, Southern Medical University, Guangzhou, P.R. China
| | - Wenjuan Yan
- Department of Stomatology, Nanfang Hospital, Guangzhou, P.R. China
- College of Stomatology, Southern Medical University, Guangzhou, P.R. China
| | - Ying Liu
- Department of Stomatology, Nanfang Hospital, Guangzhou, P.R. China
- College of Stomatology, Southern Medical University, Guangzhou, P.R. China
| | - Shuaimei Xu
- Department of Stomatology, Nanfang Hospital, Guangzhou, P.R. China
- College of Stomatology, Southern Medical University, Guangzhou, P.R. China
| | - Buling Wu
- Department of Stomatology, Nanfang Hospital, Guangzhou, P.R. China
- College of Stomatology, Southern Medical University, Guangzhou, P.R. China
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Dange M, Colman RF. Each conserved active site tyr in the three subunits of human isocitrate dehydrogenase has a different function. J Biol Chem 2010; 285:20520-5. [PMID: 20435888 DOI: 10.1074/jbc.m110.115386] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The human NAD-dependent isocitrate dehydrogenase (IDH) is a heterotetrameric mitochondrial enzyme with 2alpha:1beta:1gamma subunit ratio. The three subunits share 40-52% identity in amino acid sequence and each includes a tyrosine in a comparable position: alphaY126, betaY137, and gammaY135. To study the role of the corresponding tyrosines of each of the subunits of human NAD-IDH, the tyrosines were mutated (one subunit at a time) to Ser, Phe, or Glu. Enzymes were expressed with one mutant and two wild-type subunits. The results of characterization of the mutant enzymes suggest that betaY137 is involved in NAD binding and allosteric activation by ADP. The alphaY126 is required for catalytic activity and likely acts as a general acid in the reaction. The gammaY135 is also required for catalytic activity and may be involved in proper folding of the enzyme. The corresponding tyrosines in the three dissimilar subunits of NAD-IDH thus have distinctive functions.
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Affiliation(s)
- Mayura Dange
- Department of Chemistry and Biochemistry, University of Delaware, Newark, DE 19716, USA
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Cummins TD, Barati MT, Coventry SC, Salyer SA, Klein JB, Powell DW. Quantitative mass spectrometry of diabetic kidney tubules identifies GRAP as a novel regulator of TGF-beta signaling. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2009; 1804:653-61. [PMID: 19836472 DOI: 10.1016/j.bbapap.2009.09.029] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/24/2009] [Revised: 09/22/2009] [Accepted: 09/29/2009] [Indexed: 01/13/2023]
Abstract
The aim of this study was to define novel mediators of tubule injury in diabetic kidney disease. For this, we used state-of-the-art proteomic methods combined with a label-free quantitative strategy to define protein expression differences in kidney tubules from transgenic OVE26 type 1 diabetic and control mice. The analysis was performed with diabetic samples that displayed a pro-fibrotic phenotype. We have identified 476 differentially expressed proteins. Bioinformatic analysis indicated several clusters of regulated proteins in relevant functional groups such as TGF-beta signaling, tight junction maintenance, oxidative stress, and glucose metabolism. Mass spectrometry detected expression changes of four physiologically relevant proteins were confirmed by immunoblot analysis. Of these, the Grb2-related adaptor protein (GRAP) was up-regulated in kidney tubules from diabetic mice and fibrotic kidneys from diabetic patients, and subsequently confirmed as a novel component of TGF-beta signaling in cultured human renal tubule cells. Thus, indicating a potential novel role for GRAP in TGF-beta-induced tubule injury in diabetic kidney disease. Although we targeted a specific disease, this approach offers a robust, high-sensitivity methodology that can be applied to the discovery of novel mediators for any experimental or disease condition.
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Affiliation(s)
- Timothy D Cummins
- Department of Biochemistry and Molecular Biology, University of Louisville School of Medicine, Louisville, KY, USA
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18
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Denton RM. Regulation of mitochondrial dehydrogenases by calcium ions. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2009; 1787:1309-16. [PMID: 19413950 DOI: 10.1016/j.bbabio.2009.01.005] [Citation(s) in RCA: 591] [Impact Index Per Article: 39.4] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Received: 11/21/2008] [Revised: 01/08/2009] [Accepted: 01/09/2009] [Indexed: 11/24/2022]
Abstract
Studies in Bristol in the 1960s and 1970s, led to the recognition that four mitochondrial dehydrogenases are activated by calcium ions. These are FAD-glycerol phosphate dehydrogenase, pyruvate dehydrogenase, NAD-isocitrate dehydrogenase and oxoglutarate dehydrogenase. FAD-glycerol phosphate dehydrogenase is located on the outer surface of the inner mitochondrial membrane and is influenced by changes in cytoplasmic calcium ion concentration. The other three enzymes are located within mitochondria and are regulated by changes in mitochondrial matrix calcium ion concentration. These and subsequent studies on purified enzymes, mitochondria and intact cell preparations have led to the widely accepted view that the activation of these enzymes is important in the stimulation of the respiratory chain and hence ATP supply under conditions of increased ATP demand in many stimulated mammalian cells. The effects of calcium ions on FAD-isocitrate dehydrogenase involve binding to an EF-hand binding motif within this enzyme but the binding sites involved in the effects of calcium ions on the three intramitochondrial dehydrogenases remain to be fully established. It is also emphasised in this article that these three dehydrogenases appear only to be regulated by calcium ions in vertebrates and that this raises some interesting and potentially important developmental issues.
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Affiliation(s)
- Richard M Denton
- Department of Biochemistry, School of Medical Sciences, University of Bristol, University Walk, Bristol, BS8 ITD, UK.
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19
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Mamoon NM, Smith JK, Chatti K, Lee S, Kundrapu K, Duhé RJ. Multiple cysteine residues are implicated in Janus kinase 2-mediated catalysis. Biochemistry 2007; 46:14810-8. [PMID: 18052197 DOI: 10.1021/bi701118u] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The redox regulation of Janus kinase 2 (JAK2) is poorly understood, and there are contradictory reports as to whether the enzyme's activity is inhibited or stimulated by oxidizing conditions in the cell. Here we demonstrate that multiple cysteine residues within the JAK2 catalytic domain may be crucial for enzymatic activity. The enzyme is catalytically inactive when oxidized; activity can be restored via reduction to the thiol state. A series of recombinant variants of JAK2 were overproduced using the baculoviral expression vector system. A truncated variant of JAK2, GST/(NDelta661)rJAK2, provided evidence that the amino-terminal autoinhibitory domain was not essential for direct redox regulation and that only nine cysteine residues were potentially involved. The effect of individually and combinatorially altering these nine cysteines was examined via cysteine-to-serine mutagenesis. This identified four cysteine residues in the catalytic domain (Cys866, Cys917, Cys1094, and Cys1105) that cooperatively maintain JAK2's catalytic competency. Our data are consistent with a direct mechanism for redox regulation of JAK2 via oxidation and reduction of critical cysteine residues.
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Affiliation(s)
- Naila M Mamoon
- Department of Pharmacology and Toxicology, University of Mississippi Medical Center, Jackson, Mississippi 39216-4505, USA
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Bzymek KP, Colman RF. Role of alpha-Asp181, beta-Asp192, and gamma-Asp190 in the distinctive subunits of human NAD-specific isocitrate dehydrogenase. Biochemistry 2007; 46:5391-7. [PMID: 17432878 DOI: 10.1021/bi700061t] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Human NAD-dependent isocitrate dehydrogenase (IDH) is allosterically activated by ADP by lowering the Km for isocitrate. The enzyme has three subunit types with distinguishable sequences present in the approximate ratio 2alpha:1beta:1gamma and, per tetramer, binds 2 mol of each ligand. To evaluate whether the subunits also have distinct functions, we replaced equivalent aspartates, one subunit at a time, by asparagines; each expressed, purified enzyme was composed of one mutant and two wild-type subunits. The aspartates were chosen because beta-Asp192 and gamma-Asp190 had previously been affinity labeled by a reactive ADP analogue and alpha-Asp181 is equivalent based on sequence alignments. The alpha-D181N IDH mutant exhibits a 2000-fold decrease in Vmax, with increases of 15-fold in the Kms for Mn(II) and NAD and a much smaller change in the Km for isocitrate. In contrast, the Vmax values of the beta-D192N and gamma-D190N IDHs are only reduced 4-5-fold as compared to wild-type enzyme. The Km for NAD of the beta-D192N enzyme is 9 times that of the normal enzyme with little or no effect on the affinity for Mn(II) or isocitrate, while the Kms for coenzyme and for Mn(II) of the gamma-D190N enzyme are 19 and 72 times, respectively, that of the normal enzyme with a much smaller effect on the Km for isocitrate. Finally, all three mutant enzymes fail to respond to ADP by lowering the Km for isocitrate, although they do bind ADP. Thus, these aspartates are close to but not in the ADP site and are required for communication between the ADP and isocitrate sites. These results demonstrate that alpha-Asp181 is the only one of these aspartates essential for catalysis. Beta-Asp192 is a determinant of the enzyme's affinity for NAD, as is gamma-Asp190, while gamma-Asp190 also influences the enzyme's affinity for metal ion. We conclude that the NAD and ADP sites are shared between alpha- and beta- and alpha- and gamma-subunits, and the Mn(II) site is shared between alpha- and gamma-subunits, while the alpha-subunit is essential for catalysis. Although alpha-Asp181, beta-Asp192, and gamma-Asp190 may have derived from a common progenitor, these aspartates of the three subunits have evolved distinct functions.
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Affiliation(s)
- Krzysztof P Bzymek
- Department of Chemistry and Biochemistry, University of Delaware, Newark, Delaware 19716, USA
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Diamond TL, Bushman FD. Role of metal ions in catalysis by HIV integrase analyzed using a quantitative PCR disintegration assay. Nucleic Acids Res 2006; 34:6116-25. [PMID: 17085478 PMCID: PMC1693899 DOI: 10.1093/nar/gkl862] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Paired metal ions have been proposed to be central to the catalytic mechanisms of RNase H nucleases, bacterial transposases, Holliday junction resolvases, retroviral integrases and many other enzymes. Here we present a sensitive assay for DNA transesterification in which catalysis by human immunodeficiency virus-type 1 (HIV-1) integrase (IN) connects two DNA strands (disintegration reaction), allowing detection using quantitative PCR (qPCR). We present evidence suggesting that the three acidic residues of the IN active site function through metal binding using metal rescue. In this method, the catalytic acidic residues were each substituted with cysteines. Mn2+ binds tightly to the sulfur atoms of the cysteine residues, but Mg2+ does not. We found that Mn2+, but not Mg2+, could rescue catalysis of each cysteine-substituted enzyme, providing evidence for functionally important metal binding by all three residues. We also used the PCR-boosted assay to show that HIV-1 IN could carry out transesterification reactions involving DNA 5' hydroxyl groups as well as 3' hydroxyls as nucleophiles. Lastly, we show that Mn2+ by itself (i.e. without enzyme) can catalyze formation of a low level of PCR-amplifiable product under extreme conditions, allowing us to estimate the rate enhancement due to the IN-protein scaffold as at least 60 million-fold.
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Affiliation(s)
| | - Frederic D. Bushman
- To whom correspondence should be addressed. Tel: +1 215 573 8732; Fax: +1 215 573 4856;
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