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Cortés I, Sarotti AM. E/ Z configurational determination of oximes and related derivatives through quantum mechanics NMR calculations: scope and limitations of the leading probabilistic methods. Org Biomol Chem 2023; 21:2935-2940. [PMID: 36942946 DOI: 10.1039/d3ob00291h] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/16/2023]
Abstract
Oximes and related derivatives featuring a CN double bond are important in many areas of chemistry. Different methods for the determination of the E/Z configuration have been developed, each with its own scope and limitations. While some cannot be used when only one isomer is available, others require special NMR experiments. Here, three popular computational methodologies (DP4, DP4+, and ML-J-DP4) have been thoroughly studied using a challenging test set. Although DP4+ provides the best confidence, its computational cost might be high. On the other hand, ML-J-DP4 shows excellent performance in most cases in a fraction of CPU time. A detailed analysis of the structural factors affecting the NMR prediction and sense of the assignment is also provided.
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Affiliation(s)
- Iván Cortés
- Instituto de Química Rosario (CONICET), Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Suipacha 531, Rosario 2000, Argentina.
| | - Ariel M Sarotti
- Instituto de Química Rosario (CONICET), Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Suipacha 531, Rosario 2000, Argentina.
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2
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Wang J, Wen Y, Zheng L, Dou B, Li L, Zhao K, Wang N, Ma J. Characterization of chemical profiles of pH-sensitive cleavable D-gluconhydroximo-1, 5-lactam hydrolysates by LC–MS: A potential agent for promoting tumor-targeted drug delivery. J Pharm Biomed Anal 2020; 185:113244. [DOI: 10.1016/j.jpba.2020.113244] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2020] [Revised: 03/04/2020] [Accepted: 03/06/2020] [Indexed: 12/26/2022]
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3
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A new stereoselective synthesis of dimethyl (E)-2-[[(1-arylethylidene)amino]oxy]-3-(dimethoxyphosphoryl)succinate substituents. MONATSHEFTE FUR CHEMIE 2015. [DOI: 10.1007/s00706-014-1353-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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4
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Martin JC, Fadda E, Ito K, Woods RJ. Defining the structural origin of the substrate sequence independence of O-GlcNAcase using a combination of molecular docking and dynamics simulation. Glycobiology 2014; 24:85-96. [PMID: 24134879 PMCID: PMC3854502 DOI: 10.1093/glycob/cwt094] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2013] [Revised: 10/05/2013] [Accepted: 10/13/2013] [Indexed: 11/13/2022] Open
Abstract
Protein glycosylation with O-linked N-acetylglucosamine (O-GlcNAc) is a post-translational modification of serine/threonine residues in nucleocytoplasmic proteins. O-GlcNAc has been shown to play a role in many different cellular processes and O-GlcNAcylation is often found at sites that are also known to be phosphorylated. Unlike phosphorylation, O-GlcNAc levels are regulated by only two enzymes, O-GlcNAc transferase (OGT) and O-GlcNAc hydrolase (O-GlcNAcase or OGA). So far, no obvious consensus sequence has been found for sites of O-GlcNAcylation. Additionally, O-GlcNAcase recognizes and cleaves all O-GlcNAcylated proteins, independent of their sequence. In this work, we generate and analyze five models of O-GlcNAcylated peptides in complex with a bacterial OGA. Each of the five glycopeptides bind to OGA in a similar fashion, with OGA-peptide interactions primarily, but not exclusively, involving the peptide backbone atoms, thus explaining the lack of sensitivity to peptide sequence. Nonetheless, differences in peptide sequences, particularly at the -1 to -4 positions, lead to variations in predicted affinity, consistent with observed experimental variations in enzyme kinetics. The potential exists, therefore, to employ the present analysis to guide the development glycopeptide-specific inhibitors, or conversely, the conversion of OGA into a reagent that could target specific O-GlcNAcylated peptide sequences.
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Affiliation(s)
- Joanne C Martin
- School of Chemistry, National University of Ireland, University Road, Galway, Ireland
| | - Elisa Fadda
- School of Chemistry, National University of Ireland, University Road, Galway, Ireland
| | - Keigo Ito
- Complex Carbohydrate Research Centre, University of Georgia, 315 Riverbend Road, Athens, GA 30602, USA
| | - Robert J Woods
- School of Chemistry, National University of Ireland, University Road, Galway, Ireland
- Complex Carbohydrate Research Centre, University of Georgia, 315 Riverbend Road, Athens, GA 30602, USA
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5
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Tandon VK, Awasthi AK, Maurya HK, Mishra P. InBr3- and AgOTf-catalyzed beckmann rearrangement of (E)-benzoheterocyclic oximes. J Heterocycl Chem 2011. [DOI: 10.1002/jhet.438] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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6
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A simple and straightforward method for determination of oxime group configuration in ethanone oximes by differential NOE experiments. Tetrahedron Lett 2011. [DOI: 10.1016/j.tetlet.2011.08.117] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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7
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Usuki H, Yamamoto Y, Kumagai Y, Nitoda T, Kanzaki H, Hatanaka T. MS/MS fragmentation-guided search of TMG-chitooligomycins and their structure–activity relationship in specific β-N-acetylglucosaminidase inhibition. Org Biomol Chem 2011; 9:2943-51. [DOI: 10.1039/c0ob01090a] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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8
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Chikanishi T, Fujiki R, Hashiba W, Sekine H, Yokoyama A, Kato S. Glucose-induced expression of MIP-1 genes requires O-GlcNAc transferase in monocytes. Biochem Biophys Res Commun 2010; 394:865-70. [PMID: 20206135 DOI: 10.1016/j.bbrc.2010.02.167] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2010] [Accepted: 02/26/2010] [Indexed: 11/29/2022]
Abstract
O-glycosylation has emerged as an important modification of nuclear proteins, and it appears to be involved in gene regulation. Recently, we have shown that one of the histone methyl transferases (MLL5) is activated through O-glycosylation by O-GlcNAc transferase (OGT). Addition of this monosaccharide is essential for forming a functional complex. However, in spite of the abundance of OGT in the nucleus, the impact of nuclear O-glycosylation by OGT remains largely unclear. To address this issue, the present study was undertaken to test the impact of nuclear O-glycosylation in a monocytic cell line, THP-1. Using a cytokine array, MIP-1alpha and -1beta genes were found to be regulated by nuclear O-glycosylation. Biochemical purification of the OGT interactants from THP-1 revealed that OGT is an associating partner for distinct co-regulatory complexes. OGT recruitment and protein O-glycosylation were observed at the MIP-1alpha gene promoter; however, the known OGT partner (HCF-1) was absent when the MIP-1alpha gene promoter was not activated. From these findings, we suggest that OGT could be a co-regulatory subunit shared by functionally distinct complexes supporting epigenetic regulation.
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Affiliation(s)
- Toshihiro Chikanishi
- Institute of Molecular and Cellular Biosciences, University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-0032, Japan
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9
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Chatham JC, Marchase RB. The role of protein O-linked beta-N-acetylglucosamine in mediating cardiac stress responses. BIOCHIMICA ET BIOPHYSICA ACTA 2010; 1800:57-66. [PMID: 19607882 PMCID: PMC2814923 DOI: 10.1016/j.bbagen.2009.07.004] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/16/2009] [Revised: 07/01/2009] [Accepted: 07/06/2009] [Indexed: 11/24/2022]
Abstract
The modification of serine and threonine residues of nuclear and cytoplasmic proteins by O-linked beta-N-acetylglucosamine (O-GlcNAc) has emerged as a highly dynamic post-translational modification that plays a critical role in regulating numerous biological processes. Much of our understanding of the mechanisms underlying the role of O-GlcNAc on cellular function has been in the context of its adverse effects in mediating a range of chronic disease processes, including diabetes, cancer and neurodegenerative diseases. However, at the cellular level it has been shown that O-GlcNAc levels are increased in response to stress; augmentation of this response improved cell survival while attenuation decreased cell viability. Thus, it has become apparent that strategies that augment O-GlcNAc levels are pro-survival, whereas those that reduce O-GlcNAc levels decrease cell survival. There is a long history demonstrating the effectiveness of acute glucose-insulin-potassium (GIK) treatment and to a lesser extent glutamine in protecting against a range of stresses, including myocardial ischemia. A common feature of these approaches for metabolic cardioprotection is that they both have the potential to stimulate O-GlcNAc synthesis. Consequently, here we examine the links between metabolic cardioprotection with the ischemic cardioprotection associated with acute increases in O-GlcNAc levels. Some of the protective mechanisms associated with activation of O-GlcNAcylation appear to be transcriptionally mediated; however, there is also strong evidence to suggest that transcriptionally independent mechanisms also play a critical role. In this context we discuss the potential link between O-GlcNAcylation and cardiomyocyte calcium homeostasis including the role of non-voltage gated, capacitative calcium entry as a potential mechanism contributing to this protection.
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Affiliation(s)
- John C Chatham
- Department of Medicine, Division of Cardiovascular Disease, Center for Free Radical Biology, Center for Aging and Clinical Nutrition Research Center, University of Alabama at Birmingham, Birmingham, AL, USA.
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10
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Zou L, Yang S, Champattanachai V, Hu S, Chaudry IH, Marchase RB, Chatham JC. Glucosamine improves cardiac function following trauma-hemorrhage by increased protein O-GlcNAcylation and attenuation of NF-{kappa}B signaling. Am J Physiol Heart Circ Physiol 2009; 296:H515-23. [PMID: 19098112 PMCID: PMC2643896 DOI: 10.1152/ajpheart.01025.2008] [Citation(s) in RCA: 111] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/24/2008] [Accepted: 12/08/2008] [Indexed: 11/22/2022]
Abstract
We have previously demonstrated that in a rat model of trauma-hemorrhage (T-H), glucosamine administration during resuscitation improved cardiac function, reduced circulating levels of inflammatory cytokines, and increased tissue levels of O-linked N-acetylglucosamine (O-GlcNAc) on proteins. The mechanism(s) by which glucosamine mediated its protective effect were not determined; therefore, the goal of this study was to test the hypothesis that glucosamine treatment attenuated the activation of the nuclear factor-kappaB (NF-kappaB) signaling pathway in the heart via an increase in protein O-GlcNAc levels. Fasted male rats were subjected to T-H by bleeding to a mean arterial blood pressure of 40 mmHg for 90 min followed by resuscitation. Glucosamine treatment during resuscitation significantly attenuated the T-H-induced increase in cardiac levels of TNF-alpha and IL-6 mRNA, IkappaB-alpha phosphorylation, NF-kappaB, NF-kappaB DNA binding activity, ICAM-1, and MPO activity. LPS (2 microg/ml) increased the levels of IkappaB-alpha phosphorylation, TNF-alpha, ICAM-1, and NF-kappaB in primary cultured cardiomyocytes, which was significantly attenuated by glucosamine treatment and overexpression of O-GlcNAc transferase; both interventions also significantly increased O-GlcNAc levels. In contrast, the transfection of neonatal rat ventricular myocytes with OGT small-interfering RNA decreased O-GlcNAc transferase and O-GlcNAc levels and enhanced the LPS-induced increase in IkappaB-alpha phosphorylation. Glucosamine treatment of macrophage cell line RAW 264.7 also increased O-GlcNAc levels and attenuated the LPS-induced activation of NF-kappaB. These results demonstrate that the modulation of O-GlcNAc levels alters the response of cardiomyocytes to the activation of the NF-kappaB pathway, which may contribute to the glucosamine-mediated improvement in cardiac function following hemorrhagic shock.
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MESH Headings
- Acetylglucosamine/metabolism
- Acylation
- Animals
- Animals, Newborn
- Cardiotonic Agents/pharmacology
- Cells, Cultured
- Disease Models, Animal
- Glucosamine/pharmacology
- Hemodynamics/drug effects
- I-kappa B Proteins/metabolism
- Intercellular Adhesion Molecule-1/metabolism
- Interleukin-6/metabolism
- Lipopolysaccharides/pharmacology
- Macrophages/drug effects
- Macrophages/metabolism
- Male
- Mice
- Myocardial Contraction/drug effects
- Myocytes, Cardiac/drug effects
- Myocytes, Cardiac/enzymology
- Myocytes, Cardiac/metabolism
- N-Acetylglucosaminyltransferases/metabolism
- NF-KappaB Inhibitor alpha
- NF-kappa B/metabolism
- Peroxidase/metabolism
- Phosphorylation
- Protein Processing, Post-Translational/drug effects
- RNA Interference
- RNA, Small Interfering/metabolism
- Rats
- Rats, Sprague-Dawley
- Resuscitation
- Shock, Hemorrhagic/drug therapy
- Shock, Hemorrhagic/metabolism
- Shock, Hemorrhagic/physiopathology
- Signal Transduction/drug effects
- Transfection
- Tumor Necrosis Factor-alpha/metabolism
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Affiliation(s)
- Luyun Zou
- University of Alabama at Birmingham, Birmingham, AL, USA
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11
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Champattanachai V, Marchase RB, Chatham J. Glucosamine protects neonatal cardiomyocytes from ischemia-reperfusion injury via increased protein O-GlcNAc and increased mitochondrial Bcl-2. Am J Physiol Cell Physiol 2008; 294:C1509-20. [PMID: 18367586 PMCID: PMC2800950 DOI: 10.1152/ajpcell.00456.2007] [Citation(s) in RCA: 124] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We have previously reported that glucosamine protected neonatal rat ventricular myocytes against ischemia-reperfusion (I/R) injury, and this was associated with an increase in protein O-linked-N-acetylglucosamine (O-GlcNAc) levels. However, the protective effect of glucosamine could be mediated via pathways other that O-GlcNAc formation; thus the initial goal of the present study was to determine whether increasing O-GlcNAc transferase (OGT) expression, which catalyzes the formation of O-GlcNAc, had a protective effect similar to that of glucosamine. To better understand the potential mechanism underlying O-GlcNAc-mediated cytoprotection, we examined whether increased O-GlcNAc levels altered the expression and translocation of members of the Bcl-2 protein family. Both glucosamine (5 mM) and OGT overexpression increased basal and I/R-induced O-GlcNAc levels, significantly decreased cellular injury, and attenuated loss of cytochrome c. Both interventions also attenuated the loss of mitochondrial membrane potential induced by H2O2 and were also associated with an increase in mitochondrial Bcl-2 levels but had no effect on Bad or Bax levels. Compared with glucosamine and OGT overexpression, NButGT (100 microM), an inhibitor of O-GlcNAcase, was less protective against I/R and H2O2 and did not affect Bcl-2 expression, despite a 5- to 10-fold greater increase in overall O-GlcNAc levels. Decreased OGT expression resulted in lower basal O-GlcNAc levels, prevented the I/R-induced increase in O-GlcNAc and mitochondrial Bcl-2, and increased cellular injury. These results demonstrate that the protective effects of glucosamine are mediated via increased formation of O-GlcNAc and suggest that this is due, in part, to enhanced mitochondrial Bcl-2 translocation.
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MESH Headings
- Acetylglucosamine/metabolism
- Animals
- Animals, Newborn
- Cell Survival
- Cells, Cultured
- Cytochromes c/metabolism
- Cytoprotection
- Enzyme Inhibitors/pharmacology
- Glucosamine/metabolism
- Glycosylation
- Hydrogen Peroxide/metabolism
- Membrane Potential, Mitochondrial
- Mitochondria, Heart/drug effects
- Mitochondria, Heart/enzymology
- Mitochondria, Heart/metabolism
- Myocardial Reperfusion Injury/metabolism
- Myocardial Reperfusion Injury/pathology
- Myocardial Reperfusion Injury/prevention & control
- Myocytes, Cardiac/drug effects
- Myocytes, Cardiac/enzymology
- Myocytes, Cardiac/metabolism
- Myocytes, Cardiac/pathology
- N-Acetylglucosaminyltransferases/genetics
- N-Acetylglucosaminyltransferases/metabolism
- Protein Processing, Post-Translational/drug effects
- Protein Transport
- Proto-Oncogene Proteins c-bcl-2/metabolism
- RNA Interference
- Rats
- Rats, Sprague-Dawley
- Transfection
- Up-Regulation
- beta-N-Acetylhexosaminidases/antagonists & inhibitors
- beta-N-Acetylhexosaminidases/metabolism
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Affiliation(s)
- Voraratt Champattanachai
- Department of Cell Biology, University of Alabama at Birmingham, 1918 University Boulevard, MCLM 690, Birmingham, AL, 35294
| | - Richard B. Marchase
- Department of Cell Biology, University of Alabama at Birmingham, 1918 University Boulevard, MCLM 690, Birmingham, AL, 35294
| | - John Chatham
- Department of Cell Biology, University of Alabama at Birmingham, 1918 University Boulevard, MCLM 690, Birmingham, AL, 35294
- Department of Medicine, Division of Cardiovascular Disease, University of Alabama at Birmingham, 1918 University Boulevard, MCLM 690, Birmingham, AL, 35294
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12
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Gurcel C, Vercoutter-Edouart AS, Fonbonne C, Mortuaire M, Salvador A, Michalski JC, Lemoine J. Identification of new O-GlcNAc modified proteins using a click-chemistry-based tagging. Anal Bioanal Chem 2008; 390:2089-97. [DOI: 10.1007/s00216-008-1950-y] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2007] [Revised: 01/30/2008] [Accepted: 02/06/2008] [Indexed: 11/28/2022]
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13
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Park JE, Kwon HJ, Kang Y, Kim YS. Proteomic Analysis of O-GlcNAc Modifications Derived from Streptozotocin and Glucosamine Induced β-cell Apoptosis. BMB Rep 2007; 40:1058-68. [DOI: 10.5483/bmbrep.2007.40.6.1058] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
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14
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Forsythe ME, Love DC, Lazarus BD, Kim EJ, Prinz WA, Ashwell G, Krause MW, Hanover JA. Caenorhabditis elegans ortholog of a diabetes susceptibility locus: oga-1 (O-GlcNAcase) knockout impacts O-GlcNAc cycling, metabolism, and dauer. Proc Natl Acad Sci U S A 2006; 103:11952-7. [PMID: 16882729 PMCID: PMC1567679 DOI: 10.1073/pnas.0601931103] [Citation(s) in RCA: 134] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
A dynamic cycle of O-linked N-acetylglucosamine (O-GlcNAc) addition and removal acts on nuclear pore proteins, transcription factors, and kinases to modulate cellular signaling cascades. Two highly conserved enzymes (O-GlcNAc transferase and O-GlcNAcase) catalyze the final steps in this nutrient-driven "hexosamine-signaling pathway." A single nucleotide polymorphism in the human O-GlcNAcase gene is linked to type 2 diabetes. Here, we show that Caenorhabditis elegans oga-1 encodes an active O-GlcNAcase. We also describe a knockout allele, oga-1(ok1207), that is viable and fertile yet accumulates O-GlcNAc on nuclear pores and other cellular proteins. Interfering with O-GlcNAc cycling with either oga-1(ok1207) or the O-GlcNAc transferase-null ogt-1(ok430) altered Ser- and Thr-phosphoprotein profiles and increased glycogen synthase kinase 3beta (GSK-3beta) levels. Both the oga-1(ok1207) and ogt-1(ok430) strains showed elevated stores of glycogen and trehalose, and decreased lipid storage. These striking metabolic changes prompted us to examine the insulin-like signaling pathway controlling nutrient storage, longevity, and dauer formation in the C. elegans O-GlcNAc cycling mutants. Indeed, we found that the oga-1(ok1207) knockout augmented dauer formation induced by a temperature sensitive insulin-like receptor (daf-2) mutant under conditions in which the ogt-1(ok430)-null diminished dauer formation. Our findings suggest that the enzymes of O-GlcNAc cycling "fine-tune" insulin-like signaling in response to nutrient flux. The knockout of O-GlcNAcase (oga-1) in C. elegans mimics many of the metabolic and signaling changes associated with human insulin resistance and provides a genetically amenable model of non-insulin-dependent diabetes.
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Affiliation(s)
- Michele E. Forsythe
- Laboratory of Cell Biochemistry and Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892-0850
| | - Dona C. Love
- Laboratory of Cell Biochemistry and Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892-0850
| | - Brooke D. Lazarus
- Laboratory of Cell Biochemistry and Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892-0850
| | - Eun Ju Kim
- Laboratory of Cell Biochemistry and Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892-0850
| | - William A. Prinz
- Laboratory of Cell Biochemistry and Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892-0850
| | - Gilbert Ashwell
- Laboratory of Cell Biochemistry and Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892-0850
- *To whom correspondence may be addressed. E-mail:
or
| | - Michael W. Krause
- Laboratory of Cell Biochemistry and Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892-0850
| | - John A. Hanover
- Laboratory of Cell Biochemistry and Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892-0850
- *To whom correspondence may be addressed. E-mail:
or
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15
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Kim EJ, Kang DO, Love DC, Hanover JA. Enzymatic characterization of O-GlcNAcase isoforms using a fluorogenic GlcNAc substrate. Carbohydr Res 2006; 341:971-82. [PMID: 16584714 PMCID: PMC10561171 DOI: 10.1016/j.carres.2006.03.004] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2005] [Revised: 02/17/2006] [Accepted: 03/02/2006] [Indexed: 11/26/2022]
Abstract
A highly sensitive fluorogenic hexosaminidase substrate, fluorescein di(N-acetyl-beta-D-glucosaminide) (FDGlcNAc), was prepared essentially as described previously [Chem. Pharm. Bull. 1993, 41, 314] with some modifications. The fluorescent analog is a substrate for a number of hexosaminidases but here we have focused on the cytoplasmic O-GlcNAcase isoforms. Kinetic analysis using purified O-GlcNAcase and its splice variant (v-O-GlcNAcase) expressed in Escherichia coli suggests that FDGlcNAc is a much more efficient substrate (Km = 84.9 microM) than the conventional substrate, para-nitrophenyl 2-acetamido-2-deoxy-beta-D-glucopyranoside (pNP-beta-GlcNAc, Km = 1.1 mM) and a previously developed fluorogenic substrate, 4-methylumbelliferyl 2-acetamido-2-deoxy-beta-D-glucopyranoside [MUGlcNAc, Km = 0.43 mM; J. Biol. Chem. 2005, 280, 25313] for O-GlcNAcase. The variant O-GlcNAcase, a protein lacking the C-terminal third of the full-length O-GlcNAcase, exhibited a Km of 2.1 mM with respect to FDGlcNAc. This shorter isoform was not previously thought to exhibit O-GlcNAcase activity based on in vitro studies with pNP-beta-GlcNAc. However, both O-GlcNAcase isoforms reduced O-GlcNAc protein levels extracted from HeLa and HT-29 cells in vitro, indicating that the splice variant is a bona fide O-GlcNAcase. Fluorescein di-N-acetyl-beta-D-galactosaminide (FDGalNAc) is not cleaved by these enzymes, consistent with previous findings that the O-GlcNAcase has substrate specificity toward O-GlcNAc but not O-GalNAc. The enzymatic activity of the shorter isoform of O-GlcNAcase was first detected by using highly sensitive fluorogenic FDGlcNAc substrate. The finding that O-GlcNAcase exists as two distinct isoforms has a number of important implications for the role of O-GlcNAcase in hexosamine signaling.
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Affiliation(s)
- Eun Ju Kim
- Laboratory of Cell Biochemistry and Biology, NIDDK, National Institutes of Health, MD 20892, USA.
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16
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Rao FV, Dorfmueller HC, Villa F, Allwood M, Eggleston IM, van Aalten DMF. Structural insights into the mechanism and inhibition of eukaryotic O-GlcNAc hydrolysis. EMBO J 2006; 25:1569-78. [PMID: 16541109 PMCID: PMC1440316 DOI: 10.1038/sj.emboj.7601026] [Citation(s) in RCA: 160] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2005] [Accepted: 02/08/2006] [Indexed: 11/08/2022] Open
Abstract
O-linked N-acetylglucosamine (O-GlcNAc) modification of specific serines/threonines on intracellular proteins in higher eukaryotes has been shown to directly regulate important processes such as the cell cycle, insulin sensitivity and transcription. The structure, molecular mechanisms of catalysis, protein substrate recognition/specificity of the eukaryotic O-GlcNAc transferase and hydrolase are largely unknown. Here we describe the crystal structure, enzymology and in vitro activity on human substrates of Clostridium perfringens NagJ, a close homologue of human O-GlcNAcase (OGA), representing the first family 84 glycoside hydrolase structure. The structure reveals a deep active site pocket highly conserved with the human enzyme, compatible with binding of O-GlcNAcylated peptides. Together with mutagenesis data, the structure supports a variant of the substrate-assisted catalytic mechanism, involving two aspartic acids and an unusually positioned tyrosine. Insights into recognition of substrate come from a complex with the transition state mimic O-(2-acetamido-2-deoxy-D-glucopyranosylidene)amino-N-phenylcarbamate (Ki=5.4 nM). Strikingly, the enzyme is inhibited by the pseudosubstrate peptide Ala-Cys(-S-GlcNAc)-Ala, and has OGA activity against O-GlcNAcylated human proteins, suggesting that the enzyme is a suitable model for further studies into the function of human OGA.
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Affiliation(s)
- Francesco V Rao
- Division of Biological Chemistry & Molecular Microbiology, School of Life Sciences, University of Dundee, Dundee, UK
| | - Helge C Dorfmueller
- Division of Biological Chemistry & Molecular Microbiology, School of Life Sciences, University of Dundee, Dundee, UK
| | - Fabrizio Villa
- Division of Biological Chemistry & Molecular Microbiology, School of Life Sciences, University of Dundee, Dundee, UK
- MRC Protein Phosphorylation Unit, School of Life Sciences, University of Dundee, Dundee, UK
| | - Matthew Allwood
- Division of Biological Chemistry & Molecular Microbiology, School of Life Sciences, University of Dundee, Dundee, UK
| | - Ian M Eggleston
- Division of Biological Chemistry & Molecular Microbiology, School of Life Sciences, University of Dundee, Dundee, UK
| | - Daan M F van Aalten
- Division of Biological Chemistry & Molecular Microbiology, School of Life Sciences, University of Dundee, Dundee, UK
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