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Combret V, Rincé I, Budin-Verneuil A, Muller C, Deutscher J, Hartke A, Sauvageot N. Utilization of glycoprotein-derived N-acetylglucosamine-L-asparagine during Enterococcus faecalis infection depends on catabolic and transport enzymes of the glycosylasparaginase locus. Res Microbiol 2024; 175:104169. [PMID: 37977353 DOI: 10.1016/j.resmic.2023.104169] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2023] [Revised: 10/30/2023] [Accepted: 11/09/2023] [Indexed: 11/19/2023]
Abstract
Enterococcus faecalis is a Gram-positive clinical pathogen causing severe infections. Its survival during infection depends on its ability to utilize host-derived metabolites, such as protein-deglycosylation products. We have identified in E. faecalis OG1RF a locus (ega) involved in the catabolism of the glycoamino acid N-acetylglucosamine-L-asparagine. This locus is separated into two transcription units, genes egaRP and egaGBCD1D2, respectively. RT-qPCR experiments revealed that the expression of the ega locus is regulated by the transcriptional repressor EgaR. Electromobility shift assays evidenced that N-acetylglucosamine-L-asparagine interacts directly with the EgaR protein, which leads to the transcription of the ega genes. Growth studies with egaG, egaB and egaC mutants confirmed that the encoded proteins are necessary for N-acetylglucosamine-L-asparagine catabolism. This glycoamino acid is transported and phosphorylated by a specific phosphotransferase system EIIABC components (OG1RF_10751, EgaB, EgaC) and subsequently hydrolyzed by the glycosylasparaginase EgaG, which generates aspartate and 6-P-N-acetyl-β-d-glucosaminylamine. The latter can be used as a fermentable carbon source by E. faecalis. Moreover, Galleria mellonella larvae had a significantly higher survival rate when infected with ega mutants compared to the wild-type strain, suggesting that the loss of N-acetylglucosamine-L-asparagine utilization affects enterococcal virulence.
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Affiliation(s)
- Victor Combret
- Normandie Université, UNICAEN, CBSA, F-14000 Caen, France
| | - Isabelle Rincé
- Normandie Université, UNICAEN, CBSA, F-14000 Caen, France
| | | | - Cécile Muller
- Normandie Université, UNICAEN, CBSA, F-14000 Caen, France
| | - Josef Deutscher
- Université Paris Saclay, INRAE, Micalis Institute, 78350 Jouy en Josas, France; CNRS, Institut de Biologie Physico-Chimique UMR8261, Expression Génétique Microbienne, 75005 Paris, France
| | - Axel Hartke
- Normandie Université, UNICAEN, CBSA, F-14000 Caen, France
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Martin A, Heard R, Fung VSC. Carlos II of Spain, 'The Bewitched': cursed by aspartylglucosaminuria? BMJ Neurol Open 2021; 3:e000072. [PMID: 34632386 PMCID: PMC8477247 DOI: 10.1136/bmjno-2020-000072] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2021] [Accepted: 07/07/2021] [Indexed: 11/18/2022] Open
Abstract
Carlos II of Spain (1661–1700), last of the Spanish Habsburgs, was known as The ‘Bewitched’ due to his multiple medical issues and feeble nature. He suffered from a range of ailments extending beyond the well-known Habsburg jaw, including developmental delay, intellectual disability, dysarthria, skeletal deformity, recurrent infections, epilepsy and infertility, among others. The Habsburg dynasty of Spain was characterised by marked inbreeding, and the male line died out with Carlos II. Various diagnoses have been proffered to explain Carlos II’s infirmity, though none have been full satisfactory to explain the full breadth of his ailments. As illustrated here, it may be that aspartylglucosaminuria, an autosomal recessively inherited lysosomal storage disorder, can account for both the characteristic facial features and the wide variety of other features exhibited by Carlos II.
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Affiliation(s)
- Andrew Martin
- Movement Disorders Unit, Department of Neurology, Westmead Hospital, Westmead, New South Wales, Australia
| | - Robert Heard
- Department of Neurology, Gosford Hospital, Gosford, New South Wales, Australia.,Westmead Millennium Institute, The University of Sydney, Sydney, New South Wales, Australia
| | - Victor S C Fung
- Movement Disorders Unit, Department of Neurology, Westmead Hospital, Westmead, New South Wales, Australia
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3
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Nakamura S, Miyazaki T, Park EY. α-L-Fucosidase from Bombyx mori has broad substrate specificity and hydrolyzes core fucosylated N-glycans. INSECT BIOCHEMISTRY AND MOLECULAR BIOLOGY 2020; 124:103427. [PMID: 32561391 DOI: 10.1016/j.ibmb.2020.103427] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/27/2020] [Revised: 05/25/2020] [Accepted: 05/31/2020] [Indexed: 06/11/2023]
Abstract
N-glycans play a role in physiological functions, including glycoprotein conformation, signal transduction, and antigenicity. Insects display both α-1,6- and α-1,3-linked fucose residues bound to the innermost N-acetylglucosamine of N-glycans whereas core α-1,3-fucosylated N-glycans are not found in mammals. Functions of insect core-fucosylated glycans are not clear, and no α-L-fucosidase related to the N-glycan degradation has been identified. In the genome of the domestic silkworm, Bombyx mori, a gene for a protein, BmFucA, belonging to the glycoside hydrolase family 29 is a candidate for an α-L-fucosidase gene. In this study, BmFucA was cloned and recombinantly expressed as a glutathione-S-transferase tagged protein (GST-BmFucA). Recombinant GST-BmFucA exhibited broad substrate specificity and hydrolyzed p-nitrophenyl α-L-fucopyranoside, 2'-fucosyllactose, 3-fucosyllactose, 3-fucosyl-N,N'-diacetylchitobiose, and 6-fucosyl-N,N'-diacetylchitobiose. Further, GST-BmFucA released fucose from both pyridylaminated complex-type and paucimannose-type glycans that were core-α-1,6-fucosylated. GST-BmFucA also shows hydrolysis activity for core-fucosylated glycans attached to phospholipase A2 from bee venom. BmFucA may be involved in the catabolism of core-fucosylated N-glycans in B. mori.
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Affiliation(s)
- Shuntaro Nakamura
- Department of Agriculture, Graduate School of Integrated Science and Technology, Shizuoka University, 836 Ohya, Suruga-ku, Shizuoka, 422-8529, Japan
| | - Takatsugu Miyazaki
- Department of Agriculture, Graduate School of Integrated Science and Technology, Shizuoka University, 836 Ohya, Suruga-ku, Shizuoka, 422-8529, Japan; Green Chemistry Research Division, Research Institute of Green Science and Technology, Shizuoka University, 836 Ohya, Suruga-ku, Shizuoka, 422-8529, Japan.
| | - Enoch Y Park
- Department of Agriculture, Graduate School of Integrated Science and Technology, Shizuoka University, 836 Ohya, Suruga-ku, Shizuoka, 422-8529, Japan; Green Chemistry Research Division, Research Institute of Green Science and Technology, Shizuoka University, 836 Ohya, Suruga-ku, Shizuoka, 422-8529, Japan
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Unique Microbial Catabolic Pathway for the Human Core N-Glycan Constituent Fucosyl-α-1,6- N-Acetylglucosamine-Asparagine. mBio 2020; 11:mBio.02804-19. [PMID: 31937642 PMCID: PMC6960285 DOI: 10.1128/mbio.02804-19] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
The gastrointestinal tract accommodates more than 1014 microorganisms that have an enormous impact on human health. The mechanisms enabling commensal bacteria and administered probiotics to colonize the gut remain largely unknown. The ability to utilize host-derived carbon and energy resources available at the mucosal surfaces may provide these bacteria with a competitive advantage in the gut. Here, we have identified in the commensal species Lactobacillus casei a novel metabolic pathway for the utilization of the glycoamino acid fucosyl-α-1,6-N-GlcNAc-Asn, which is present in the core-fucosylated N-glycoproteins from mammalians. These results give insight into the molecular interactions between the host and commensal/probiotic bacteria and may help to devise new strategies to restore gut microbiota homeostasis in diseases associated with dysbiotic microbiota. The survival of commensal bacteria in the human gut partially depends on their ability to metabolize host-derived molecules. The use of the glycosidic moiety of N-glycoproteins by bacteria has been reported, but the role of N-glycopeptides or glycoamino acids as the substrates for bacterial growth has not been evaluated. We have identified in Lactobacillus casei strain BL23 a gene cluster (alf-2) involved in the catabolism of the glycoamino acid fucosyl-α-1,6-N-GlcNAc-Asn (6′FN-Asn), a constituent of the core-fucosylated structures of mammalian N-glycoproteins. The cluster consists of the genes alfHC, encoding a major facilitator superfamily (MFS) permease and the α-l-fucosidase AlfC, and the divergently oriented asdA (aspartate 4-decarboxylase), alfR2 (transcriptional regulator), pepV (peptidase), asnA2 (glycosyl-asparaginase), and sugK (sugar kinase) genes. Knockout mutants showed that alfH, alfC, asdA, asnA2, and sugK are necessary for efficient 6′FN-Asn utilization. The alf-2 genes are induced by 6′FN-Asn, but not by its glycan moiety, via the AlfR2 regulator. The constitutive expression of alf-2 genes in an alfR2 strain allowed the metabolism of a variety of 6′-fucosyl-glycans. However, GlcNAc-Asn did not support growth in this mutant background, indicating that the presence of a 6′-fucose moiety is crucial for substrate transport via AlfH. Within bacteria, 6′FN-Asn is defucosylated by AlfC, generating GlcNAc-Asn. This glycoamino acid is processed by the glycosylasparaginase AsnA2. GlcNAc-Asn hydrolysis generates aspartate and GlcNAc, which is used as a fermentable source by L.casei. These data establish the existence in a commensal bacterial species of an exclusive metabolic pathway likely to scavenge human milk and mucosal fucosylated N-glycopeptides in the gastrointestinal tract.
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Pande S, Guo HC. The T99K variant of glycosylasparaginase shows a new structural mechanism of the genetic disease aspartylglucosaminuria. Protein Sci 2019; 28:1013-1023. [PMID: 30901125 DOI: 10.1002/pro.3607] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2019] [Accepted: 03/21/2019] [Indexed: 12/16/2022]
Abstract
Aspartylglucosaminuria (AGU) is an inherited disease caused by mutations in a lysosomal amidase called aspartylglucosaminidase (AGA) or glycosylasparaginase (GA). This disorder results in an accumulation of glycoasparagines in the lysosomes of virtually all cell types, with severe clinical symptoms affecting the central nervous system, skeletal abnormalities, and connective tissue lesions. GA is synthesized as a single-chain precursor that requires an intramolecular autoprocessing to form a mature amidase. Previously, we showed that a Canadian AGU mutation disrupts this obligatory intramolecular autoprocessing with the enzyme trapped as an inactive precursor. Here, we report biochemical and structural characterization of a model enzyme corresponding to a new American AGU allele, the T99K variant. Unlike other variants with known 3D structures, this T99K model enzyme still has autoprocessing capacity to generate a mature form. However, its amidase activity to digest glycoasparagines remains low, consistent with its association with AGU. We have determined a 1.5-Å-resolution structure of this new AGU model enzyme and built an enzyme-substrate complex to provide a structural basis to analyze the negative effects of the T99K point mutation on KM and kcat of the amidase. It appears that a "molecular clamp" capable of fixing local disorders at the dimer interface might be able to rescue the deficiency of this new AGU variant.
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Affiliation(s)
- Suchita Pande
- Department of Biological Sciences, University of Massachusetts Lowell, Lowell, Massachusetts, 01854
| | - Hwai-Chen Guo
- Department of Biological Sciences, University of Massachusetts Lowell, Lowell, Massachusetts, 01854
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6
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Lu Y, Li C, Wei M, Jia Y, Song J, Zhang Y, Wang C, Huang L, Wang Z. Release, Separation, and Recovery of Monomeric Reducing N-Glycans with Pronase E Combined with 9-Chloromethyl Chloroformate and Glycosylasparaginase. Biochemistry 2019; 58:1120-1130. [PMID: 30661358 DOI: 10.1021/acs.biochem.8b01224] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The glycan moiety of glycoproteins plays key roles in various biological processes. However, there are few versatile methods for releasing, separating, and recovering monomeric reducing N-glycans for further functional analysis. In this study, we developed a new method to achieve the release, separation, and recovery of monomeric reducing N-glycans using enzyme E (Pronase E) combined with 9-chloromethyl chloroformate (Fmoc-Cl) and glycosylasparaginase (GA). Ovalbumin, ribonuclease B, ginkgo, and pine nut glycoproteins were used as materials and sequentially enzymatically hydrolyzed with Pronase E, derivatized with Fmoc-Cl, and enzymatically hydrolyzed with GA. The products produced by this method were then detected by electrospray ionization mass spectrometry, high-performance liquid chromatography (HPLC), and online hydrophilic interaction chromatography (HILIC-MS) separation. The results showed that all N-glycans with essentially one amino acid obtained with Pronase E were labeled with Fmoc-Cl and could be efficiently separated and detected via HPLC and HILIC-MS. Finally, the isolated Asn-glycan derivatives were digested with GA, enabling the recovery of all monomeric reducing N-glycans modified by core α-1,3 fucose. This method was simple, inexpensive, and broadly applicable and could therefore be quite important for analysis of the structure-function relationships of glycans.
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Affiliation(s)
- Yu Lu
- The College of Life Sciences , Northwest University , Xi'an 710069 , China
| | - Cheng Li
- The College of Life Sciences , Northwest University , Xi'an 710069 , China
| | - Ming Wei
- The College of Life Sciences , Northwest University , Xi'an 710069 , China
| | - Yue Jia
- The College of Life Sciences , Northwest University , Xi'an 710069 , China
| | - Jingjing Song
- The College of Life Sciences , Northwest University , Xi'an 710069 , China
| | - Ying Zhang
- The College of Life Sciences , Northwest University , Xi'an 710069 , China
| | - Chengjian Wang
- The College of Life Sciences , Northwest University , Xi'an 710069 , China.,Glycobiology and Glycotechnology Research Center, College of Food Science and Technology , Northwest University , Xi'an 710069 , China
| | - Linjuan Huang
- The College of Life Sciences , Northwest University , Xi'an 710069 , China.,Glycobiology and Glycotechnology Research Center, College of Food Science and Technology , Northwest University , Xi'an 710069 , China
| | - Zhongfu Wang
- The College of Life Sciences , Northwest University , Xi'an 710069 , China.,Glycobiology and Glycotechnology Research Center, College of Food Science and Technology , Northwest University , Xi'an 710069 , China
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7
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Abstract
Lysosomal storage diseases (LSDs) are a group of over 70 diseases that are characterized by lysosomal dysfunction, most of which are inherited as autosomal recessive traits. These disorders are individually rare but collectively affect 1 in 5,000 live births. LSDs typically present in infancy and childhood, although adult-onset forms also occur. Most LSDs have a progressive neurodegenerative clinical course, although symptoms in other organ systems are frequent. LSD-associated genes encode different lysosomal proteins, including lysosomal enzymes and lysosomal membrane proteins. The lysosome is the key cellular hub for macromolecule catabolism, recycling and signalling, and defects that impair any of these functions cause the accumulation of undigested or partially digested macromolecules in lysosomes (that is, 'storage') or impair the transport of molecules, which can result in cellular damage. Consequently, the cellular pathogenesis of these diseases is complex and is currently incompletely understood. Several LSDs can be treated with approved, disease-specific therapies that are mostly based on enzyme replacement. However, small-molecule therapies, including substrate reduction and chaperone therapies, have also been developed and are approved for some LSDs, whereas gene therapy and genome editing are at advanced preclinical stages and, for a few disorders, have already progressed to the clinic.
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8
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Pande S, Bizilj W, Guo HC. Biochemical and structural insights into an allelic variant causing the lysosomal storage disorder - aspartylglucosaminuria. FEBS Lett 2018; 592:2550-2561. [PMID: 29993127 DOI: 10.1002/1873-3468.13190] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2018] [Revised: 06/29/2018] [Accepted: 07/03/2018] [Indexed: 01/03/2023]
Abstract
Aspartylglucosaminuria (AGU) is a lysosomal storage disorder caused by defects of the hydrolase glycosylasparaginase (GA). Previously, we showed that a Canadian AGU mutation disrupts an obligatory intramolecular autoprocessing with the enzyme trapped as an inactive precursor. Here, we report biochemical and structural characterizations of a model enzyme corresponding to a Finnish AGU allele, the T234I variant. Unlike the Canadian counterpart, the Finnish variant is capable of a slow autoprocessing to generate detectible hydrolyzation activity of the natural substrate of GA. We have determined a 1.6 Å-resolution structure of the Finnish AGU model and built an enzyme-substrate complex to provide a structural basis for analyzing the negative effects of the point mutation on KM and kcat of the mature enzyme. ENZYME Glycosylasparaginase or aspartylglucosaminidase, EC3.5.1.26.
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Affiliation(s)
- Suchita Pande
- Department of Biological Sciences, University of Massachusetts Lowell, MA, USA
| | - William Bizilj
- Department of Biological Sciences, University of Massachusetts Lowell, MA, USA
| | - Hwai-Chen Guo
- Department of Biological Sciences, University of Massachusetts Lowell, MA, USA
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10
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Catabolism of N-glycoproteins in mammalian cells: Molecular mechanisms and genetic disorders related to the processes. Mol Aspects Med 2016; 51:89-103. [DOI: 10.1016/j.mam.2016.05.004] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2016] [Revised: 05/11/2016] [Accepted: 05/24/2016] [Indexed: 11/17/2022]
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Sui L, Lakshminarasimhan D, Pande S, Guo HC. Structural basis of a point mutation that causes the genetic disease aspartylglucosaminuria. Structure 2014; 22:1855-1861. [PMID: 25456816 DOI: 10.1016/j.str.2014.09.014] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2014] [Revised: 08/30/2014] [Accepted: 09/17/2014] [Indexed: 10/24/2022]
Abstract
Aspartylglucosaminuria (AGU) is a lysosomal storage disease caused by a metabolic disorder of lysosomes to digest Asn-linked glycoproteins. The specific enzyme linked to AGU is a lysosomal hydrolase called glycosylasparaginase. Crystallographic studies revealed that a surface loop blocks the catalytic center of the mature hydrolase. Autoproteolysis is therefore required to remove this P loop and open up the hydrolase center. Nonetheless, AGU mutations result in misprocessing of their precursors and are deficient in hydrolyzing glycoasparagines. To understand the catalytic and structural consequences of AGU mutations, we have characterized two AGU models, one corresponding to a Finnish allele and the other found in a Canadian family. We also report a 2.1 Å resolution structure of the latter AGU model. The current crystallographic study provides a high-resolution structure of an AGU mutant. It reveals substantial conformation changes at the defective autocleavage site of the AGU mutant, which is trapped as an inactive precursor.
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Affiliation(s)
- Lufei Sui
- Department of Biological Sciences, University of Massachusetts Lowell, 1 University Avenue, Lowell, MA 01854, USA
| | - Damodharan Lakshminarasimhan
- Department of Biological Sciences, University of Massachusetts Lowell, 1 University Avenue, Lowell, MA 01854, USA
| | - Suchita Pande
- Department of Biological Sciences, University of Massachusetts Lowell, 1 University Avenue, Lowell, MA 01854, USA
| | - Hwai-Chen Guo
- Department of Biological Sciences, University of Massachusetts Lowell, 1 University Avenue, Lowell, MA 01854, USA.
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Chantret I, Couvineau A, Moore S. [Novel deglycosylation-independent roles for peptide N-glycanase]. Med Sci (Paris) 2014; 30:47-54. [PMID: 24472459 DOI: 10.1051/medsci/20143001013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
The primary function of peptide N-glycanase (PNGase) is thought to be the deglycosylation of endoplasmic reticulum associated degradation (ERAD) substrates. However, inhibition of PNGase appears to have little effect upon the destruction rate of many ERAD substrates, and recent data demonstrate deglycosylation-independent functions for PNGase. Whatever the roles of PNGase turn out to be, the identification of a patient presenting with PNGase deficiency will advance our understanding of the importance of this multifunctional protein in human physiology.
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Affiliation(s)
- Isabelle Chantret
- Inserm U773, centre de recherche Bichat Beaujon CRB3, Faculté de médecine Xavier Bichat, 75018 Paris, France - Université Paris 7 Denis Diderot, site Bichat, 16, rue Henri Huchard, 75018, Paris, France
| | - Alain Couvineau
- Inserm U773, centre de recherche Bichat Beaujon CRB3, Faculté de médecine Xavier Bichat, 75018 Paris, France - Université Paris 7 Denis Diderot, site Bichat, 16, rue Henri Huchard, 75018, Paris, France
| | - Stuart Moore
- Inserm U773, centre de recherche Bichat Beaujon CRB3, Faculté de médecine Xavier Bichat, 75018 Paris, France - Université Paris 7 Denis Diderot, site Bichat, 16, rue Henri Huchard, 75018, Paris, France
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Genome-wide association study of serum selenium concentrations. Nutrients 2013; 5:1706-18. [PMID: 23698163 PMCID: PMC3708345 DOI: 10.3390/nu5051706] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2013] [Revised: 05/02/2013] [Accepted: 05/09/2013] [Indexed: 11/23/2022] Open
Abstract
Selenium is an essential trace element and circulating selenium concentrations have been associated with a wide range of diseases. Candidate gene studies suggest that circulating selenium concentrations may be impacted by genetic variation; however, no study has comprehensively investigated this hypothesis. Therefore, we conducted a two-stage genome-wide association study to identify genetic variants associated with serum selenium concentrations in 1203 European descents from two cohorts: the Prostate, Lung, Colorectal, and Ovarian (PLCO) Cancer Screening and the Women’s Health Initiative (WHI). We tested association between 2,474,333 single nucleotide polymorphisms (SNPs) and serum selenium concentrations using linear regression models. In the first stage (PLCO) 41 SNPs clustered in 15 regions had p < 1 × 10−5. None of these 41 SNPs reached the significant threshold (p = 0.05/15 regions = 0.003) in the second stage (WHI). Three SNPs had p < 0.05 in the second stage (rs1395479 and rs1506807 in 4q34.3/AGA-NEIL3; and rs891684 in 17q24.3/SLC39A11) and had p between 2.62 × 10−7 and 4.04 × 10−7 in the combined analysis (PLCO + WHI). Additional studies are needed to replicate these findings. Identification of genetic variation that impacts selenium concentrations may contribute to a better understanding of which genes regulate circulating selenium concentrations.
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Xia B, Asif G, Arthur L, Pervaiz MA, Li X, Liu R, Cummings RD, He M. Oligosaccharide analysis in urine by maldi-tof mass spectrometry for the diagnosis of lysosomal storage diseases. Clin Chem 2013; 59:1357-68. [PMID: 23676310 DOI: 10.1373/clinchem.2012.201053] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
BACKGROUND There are 45 known genetic diseases that impair the lysosomal degradation of macromolecules. The loss of a single lysosomal hydrolase leads to the accumulation of its undegraded substrates in tissues and increases of related glycoconjugates in urine, some of which can be detected by screening of free oligosaccharides (FOS) in urine. Traditional 1-dimensional TLC for urine oligosaccharide analysis has limited analytical specificity and sensitivity. We developed fast and robust urinary FOS and glycoaminoacid analyses by MALDI-time-of-flight/time-of-flight (MALDI-TOF/TOF) mass spectrometry for the diagnosis of oligosaccharidoses and other lysosomal storage diseases. METHODS The FOS in urine equivalent to 0.09 mg creatinine were purified through sequential passage over a Sep-Pak C18 column and a carbograph column and were then permethylated. MALDI-TOF/TOF was used to analyze the permethylated FOS. We studied urine samples from individuals in 7 different age groups ranging from 0-1 months to ≥ 17 years as well as urine from known patients with different lysosomal storage diseases. RESULTS We identified diagnostic urinary FOS patterns for α-mannosidosis, galactosialidosis, mucolipidosis type II/III, sialidosis, α-fucosidosis, aspartylglucosaminuria (AGU), Pompe disease, Gaucher disease, and GM1 and GM2 gangliosidosis. Interestingly, the increase in urinary FOS characteristic of lysosomal storage diseases relative to normal FOS appeared to correlate with the disease severity. CONCLUSIONS The analysis of urinary FOS by MALDI-TOF/TOF is a powerful tool for first-tier screening of oligosaccharidoses and lysosomal storage diseases.
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Affiliation(s)
- Baoyun Xia
- Department of Human Genetics, Emory University, 2165 N. Decatur Rd., Decatur, GA, 30033, USA
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15
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Witte MD, van der Marel GA, Aerts JMFG, Overkleeft HS. Irreversible inhibitors and activity-based probes as research tools in chemical glycobiology. Org Biomol Chem 2011; 9:5908-26. [DOI: 10.1039/c1ob05531c] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
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16
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Wang Y, Guo HC. Crystallographic snapshot of a productive glycosylasparaginase-substrate complex. J Mol Biol 2006; 366:82-92. [PMID: 17157318 PMCID: PMC1865511 DOI: 10.1016/j.jmb.2006.09.051] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2006] [Revised: 09/02/2006] [Accepted: 09/20/2006] [Indexed: 11/18/2022]
Abstract
Glycosylasparaginase (GA) plays an important role in asparagine-linked glycoprotein degradation. A deficiency in the activity of human GA leads to a lysosomal storage disease named aspartylglycosaminuria. GA belongs to a superfamily of N-terminal nucleophile hydrolases that autoproteolytically generate their mature enzymes from inactive single chain protein precursors. The side-chain of the newly exposed N-terminal residue then acts as a nucleophile during substrate hydrolysis. By taking advantage of mutant enzyme of Flavobacterium meningosepticum GA with reduced enzymatic activity, we have obtained a crystallographic snapshot of a productive complex with its substrate (NAcGlc-Asn), at 2.0 A resolution. This complex structure provided us an excellent model for the Michaelis complex to examine the specific contacts critical for substrate binding and catalysis. Substrate binding induces a conformational change near the active site of GA. To initiate catalysis, the side-chain of the N-terminal Thr152 is polarized by the free alpha-amino group on the same residue, mediated by the side-chain hydroxyl group of Thr170. Cleavage of the amide bond is then accomplished by a nucleophilic attack at the carbonyl carbon of the amide linkage in the substrate, leading to the formation of an acyl-enzyme intermediate through a negatively charged tetrahedral transition state.
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Affiliation(s)
| | - Hwai-Chen Guo
- *Corresponding author: Hwai-Chen Guo, Department of Physiology and Biophysics, Boston University School of Medicine, 715 Albany Street, Boston, MA 02118-2526, telephone: 617-638-4023, fax: 617-638-4041, E-mail:
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Ramsay SL, Meikle PJ, Hopwood JJ, Clements PR. Profiling oligosaccharidurias by electrospray tandem mass spectrometry: Quantifying reducing oligosaccharides. Anal Biochem 2005; 345:30-46. [PMID: 16111643 DOI: 10.1016/j.ab.2005.06.042] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2005] [Revised: 06/14/2005] [Accepted: 06/27/2005] [Indexed: 11/15/2022]
Abstract
A method to semiquantify urinary oligosaccharides from patients suffering from oligosaccharidurias is presented. 1-Phenyl-3-methyl-5-pyrazolone has been used to derivatize urinary oligosaccharides prior to analysis by electrospray ionization-tandem mass spectrometry (ESI-MS/MS). Disease-specific oligosaccharides were identified for several oligosaccharidurias, including GM1 gangliosidosis, GM2 gangliosidosis, sialic acid storage disease, sialidase/neuraminidase deficiency, galactosialidosis, I-cell disease, fucosidosis, Pompe and Gaucher diseases, and alpha-mannosidosis. The oligosaccharides were referenced against the internal standard, methyl lactose, to produce ratios for comparison with control samples. Elevations in specific urinary oligosaccharides were indicative of lysosomal disease and the defective catabolic enzyme. This method has been adapted to enable assay of large sample numbers and could readily be extended to other oligosaccharidurias and to monitor oligosaccharide levels in patients receiving treatment. It also has immediate potential for incorporation into a newborn screening program.
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Affiliation(s)
- Steven L Ramsay
- Lysosomal Diseases Research Unit, Department of Genetic Medicine, Women's and Children's Hospital, North Adelaide, SA 5006, Australia
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18
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Abstract
The lysosomal catabolism of glycoproteins is part of the normal turnover of cellular constituents and the cellular homeostasis of glycosylation. Glycoproteins are delivered to lysosomes for catabolism either by endocytosis from outside the cell or by autophagy within the cell. Once inside the lysosome, glycoproteins are broken down by a combination of proteases and glycosidases, with the characteristic properties of soluble lysosomal hydrolases. The proteases consist of a mixture of endopeptidases and exopeptidases, which act in concert to produce a mixture of amino acids and dipeptides, which are transported across the lysosomal membrane into the cytosol by a combination of diffusion and carrier-mediated transport. Although the glycans of all mature glycoproteins are probably degraded in lysosomes, the breakdown of N-linked glycans has been studied most intensively. The catabolic pathways for high-mannose, hybrid, and complex glycans have been established. They are bidirectional with concurrent sequential removal of monosaccharides from the nonreducing end by exoglycosidases and proteolysis and digestion of the carbohydrate-polypeptide linkage at the reducing end. The process is initiated by the removal of any core and peripheral fucose, which is a prerequisite for the action of the peptide N-glycanase aspartylglucosaminidase, which hydrolyzes the glycan-peptide bond. This enzyme also requires free alpha carboxyl and amino groups on the asparagine residue, implying extensive prior proteolysis. The catabolism of O-linked glycans has not been studied so intensively, but many lysosomal glycosidases appear to act on the same linkages whether they are in N- or O-linked glycans, glycosaminoglycans, or glycolipids. The monosaccharides liberated during the breakdown of N- and O-linked glycans are transported across the lysosomal membrane into the cytosol by a combination of diffusion and carrier-mediated transport. Defects in these pathways lead to lysosomal storage diseases. The structures of some of the oligosaccharides that accumulate in these diseases are not digestion intermediates in the lysosomal catabolic pathways but correspond to intermediates in the biosynthetic pathway for N-linked glycans, suggesting another route of delivery of glycans to the lysosome. Incorrectly folded or glycosylated proteins that are rejected by the quality control mechanism are broken down in the ER and cytoplasm and the end product of the cytosolic degradation of N-glycans is delivered to the lysosomes. This route is enhanced in cells actively secreting glycoproteins or producing increased amounts of aberrant glycoproteins. Thus interaction between the lysosome and proteasome is important for the regulation of the biosynthesis and distribution of N-linked glycoproteins. Another example of the extralysosomal function of lysosomal enzymes is the release of lysosomal proteases into the cytosol to initiate the lysosomal pathway of apoptosis.
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Affiliation(s)
- Bryan Winchester
- Institute of Child Health at Great Ormond Street Hospital, University College London, 30 Guilford Street, London WC1N 1EH, U.K
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19
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Lin HH, Chang GW, Davies JQ, Stacey M, Harris J, Gordon S. Autocatalytic Cleavage of the EMR2 Receptor Occurs at a Conserved G Protein-coupled Receptor Proteolytic Site Motif. J Biol Chem 2004; 279:31823-32. [PMID: 15150276 DOI: 10.1074/jbc.m402974200] [Citation(s) in RCA: 158] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Post-translational cleavage at the G protein-coupled receptor proteolytic site (GPS) has been demonstrated in many class B2 G protein-coupled receptors as well as other cell surface proteins such as polycystin-1. However, the mechanism of the GPS proteolysis has never been elucidated. Here we have characterized the cleavage of the human EMR2 receptor and identified the molecular mechanism of the proteolytic process at the GPS. Proteolysis at the highly conserved His-Leu downward arrow Ser(518) cleavage site can occur inside the endoplasmic reticulum compartment, resulting in two protein subunits that associate noncovalently as a heterodimer. Site-directed mutagenesis of the P(+1) cleavage site (Ser(518)) shows an absolute requirement of a Ser, Thr, or Cys residue for efficient proteolysis. Substitution of the P(-2) His residue to other amino acids produces slow processing precursor proteins, which spontaneously hydrolyze in a defined cell-free system. Further biochemical characterization indicates that the GPS proteolysis is mediated by an autocatalytic intramolecular reaction similar to that employed by the N-terminal nucleophile hydrolases, which are known to activate themselves by self-catalyzed cis-proteolysis. We propose here that the autoproteolytic cleavage of EMR2 represents a paradigm for the other GPS motif-containing proteins and suggest that these GPS proteins belong to a cell surface receptor subfamily of N-terminal nucleophile hydrolases.
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Affiliation(s)
- Hsi-Hsien Lin
- Sir William Dunn School of Pathology, The University of Oxford, South Parks Road, Oxford OX1 3RE, United Kingdom.
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20
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Abstract
Glycosylasparaginase uses an autoproteolytic processing mechanism, through an N-O acyl shift, to generate a mature/active enzyme from a single-chain precursor. Structures of glycosylasparaginase precursors in complex with a glycine inhibitor have revealed the backbone in the immediate vicinity of the scissile peptide bond to be in a distorted trans conformation, which is believed to be the driving force for the N-O acyl shift to break the peptide bond. Here we report the effects of point mutation D151N. In addition to the loss of the base essential in autoproteolysis, this mutation also eradicates the backbone distortion near the scissile peptide bond. Binding of the glycine inhibitor to the autoproteolytic site of the D151N mutant does not restore the backbone distortion. Therefore, Asp151 plays a dual role, acting as the general base to activate the nucleophile and holding the distorted trans conformation that is critical for initiating an N-O acyl shift.
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Affiliation(s)
- Xiaofeng Qian
- Department of Physiology and Biophysics, Boston University School of Medicine, 715 Albany Street, Boston, MA 02118, USA
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21
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Du W, Risley JM. Acylation is rate-limiting in glycosylasparaginase-catalyzed hydrolysis of N4-(4'-substituted phenyl)-L-asparagines. Org Biomol Chem 2003; 1:1900-5. [PMID: 12945771 DOI: 10.1039/b301513k] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Glycosylasparaginase catalyzes the hydrolysis of the N-glycosylic bond between N-acetyl-D-glucosamine and L-asparagine in the catabolism of glycoproteins. The mechanism has been proposed to resemble that of serine proteases involving an acylation step where a nucleophilic attack by a catalytic Thr residue on the carbonyl carbon of the N-glycosylic bond gives rise to a covalent beta-aspartyl-enzyme intermediate, and a deacylation step to give the final products. The question posed in this study was: Is the acylation step the rate-limiting step in the hydrolysis reaction as in serine proteases? To answer this question a series of mostly new substituted anilides was synthesized and characterized, and their hydrolysis reactions catalyzed by glycosylasparaginase from human amniotic fluid were studied. Five N4-(4'-substituted phenyl)-L-asparagine compounds were synthesized and characterized: 4'-hydrogen, 4'-ethyl, 4'-bromo, 4'-nitro, and 4'-methoxy. Each of these anilides was a substrate for the enzyme. Hammett plots of the kinetic parameters showed that acylation is the rate-limiting step in the reaction and that upon binding the electron distribution of the substrate is perturbed toward the transition state. This is the first direct evidence that acylation is the rate-limiting step in the enzyme-catalyzed reaction. A Brønsted plot indicates a small, negative charge (-0.25) on the nitrogen atom of the leaving group anilines containing electron-withdrawing groups, and a small, positive charge (0.43) on the nitrogen atom of the leaving group anilines containing electron-donating groups. The free energy (incremental) change of binding (delta deltaGb) in the enzyme-substrate transition state complexes shows that substitution of a substituted phenyl group for the pyranosyl group in the natural substrate results in an overall loss of binding energy equivalent to a weak hydrogen bond, the magnitude of which is dependent on the substituent group. The data are consistent with a mechanism for glycosylasparaginase involving rapid formation of a tetrahedral structure upon substrate binding, and a rate-limiting breakdown of the tetrahedral structure to a covalent beta-aspartyl-enzyme intermediate that is dependent on the electronic properties of the substituent group and on the degree of protonation of the leaving group in the transition state by a general acid.
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Affiliation(s)
- Wenjun Du
- Department of Chemistry, The University of North Carolina at Charlotte, 9201 University City Blvd., Charlotte, North Carolina 28223-0001, USA
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22
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Risley JM, Huang DH, Kaylor JJ, Malik JJ, Xia YQ. Glycosylasparaginase inhibition studies: competitive inhibitors, transition state mimics, noncompetitive inhibitors. JOURNAL OF ENZYME INHIBITION 2002; 16:269-74. [PMID: 11697047 DOI: 10.1080/14756360109162375] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
Glycosylasparaginase catalyzes the hydrolysis of the N-glycosylic bond between asparagine and N-acetylglucosamine in the catabolism of N-linked glycoproteins. Previously only three competitive inhibitors, one noncompetitive inhibitor, and one irreversible inhibitor of glycosylasparaginase activity had been reported. Using human glycosylasparaginase from human amniotic fluid, L-aspartic acid and four of its analogues, where the alpha-amino group was substituted with a chloro, bromo, methyl or hydrogen, were competitive inhibitors having Ki values between 0.6-7.7 mM. These results provide supporting evidence for a proposed intramolecular autoproteolytic activation reaction. A proposed phosphono transition state mimic and a sulfo transition state mimic were competitive inhibitors with Ki values 0.9 mM and 1.4 mM, respectively. These results support a mechanism for the enzyme-catalyzed reaction involving formation of a tetrahedral high-energy intermediate. Three analogues of the natural substrate were noncompetitive inhibitors with Ki values between 0.56-0.75 mM, indicating the presence of a second binding site that may recognize (substituted)acetamido groups.
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Affiliation(s)
- J M Risley
- Department of Chemistry, University of North Carolina at Charlotte, Charlotte, NC 28223, USA.
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23
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Risley JM, Huang DH, Kaylor JJ, Malik JJ, Xia YQ, York WM. Glycosylasparaginase activity requires the alpha-carboxyl group, but not the alpha-amino group, on N(4)-(2-Acetamido-2-deoxy-beta-D-glucopyranosyl)-L-asparagine. Arch Biochem Biophys 2001; 391:165-70. [PMID: 11437347 DOI: 10.1006/abbi.2001.2416] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Glycosylasparaginase catalyzes the hydrolysis of the N-glycosylic bond in N(4)-(2-acetamido-2-deoxy-beta-D-glucopyranosyl)-L-asparagine in the catabolism of N-linked oligosaccharides. A deficiency, or absence, of enzyme activity gives rise to aspartylglycosaminuria, the most common disorder of glycoprotein metabolism. The enzyme catalyzes the hydrolysis of a variety of asparagine and aspartyl compounds containing a free alpha-carboxyl group and a free alpha-amino group; computational studies suggest that the alpha-amino group actively participates in the catalytic mechanism. In order to study the importance of the alpha-carboxyl group and the alpha-amino group on the natural substrate to the reaction catalyzed by the enzyme, 14 analogues of the natural substrate were studied where the structure of the aspartyl group of the substrate was changed. The incremental binding energy (DeltaDeltaGb) for those analogues that were substrates was calculated. The results show that the alpha-amino group may be substituted with a group of comparable size, for the alpha-amino group contributes little, if any, to the transition state binding energy of the natural substrate. The alpha-amino group position acts as an "anchor" in the binding site for the substrate. On the other hand, the alpha-carboxyl group is necessary for enzyme activity; removal of the alpha-carboxyl group or changing it to an alpha-carboxamide group results in no hydrolysis reaction. Also, N-acetyl-D-glucosamine is not sufficient for binding to the active site for efficient hydrolysis by the enzyme. These results provide supporting evidence for a proposed intramolecular autoproteolytic activation reaction for the enzyme. However, the results raise a question as to an important role for the alpha-amino group in the catalytic mechanism as indicated in computational studies.
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Affiliation(s)
- J M Risley
- Department of Chemistry, The University of North Carolina at Charlotte, Charlotte, North Carolina 28223, USA.
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24
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Dunder U, Mononen I. Human leukocyte glycosylasparaginase: cell-to-cell transfer and properties in correction of aspartylglycosaminuria. FEBS Lett 2001; 499:77-81. [PMID: 11418116 DOI: 10.1016/s0014-5793(01)02526-1] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Aspartylglycosaminuria (AGU), a severe lysosomal storage disease, is caused by the deficiency of the lysosomal enzyme, glycosylasparaginase (GA), and accumulation of aspartylglucosamine (GlcNAc-Asn) in tissues. Here we show that human leukocyte glycosylasparaginase can correct the metabolic defect in Epstein-Barr virus (EBV)-transformed AGU lymphocytes rapidly and effectively by mannose-6-phosphate receptor-mediated endocytosis or by contact-mediated cell-to-cell transfer from normal EBV-transformed lymphocytes, and that 2-7% of normal activity is sufficient to correct the GlcNAc-Asn metabolism in the cells. Cell-to-cell contact is obligatory for the transfer of GA since normal transformed lymphocytes do not excrete GA into extracellular medium. The combined evidence indicates that cell-to-cell transfer of GA plays a main role in enzyme replacement therapy of AGU by normal lymphocytes.
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Affiliation(s)
- U Dunder
- Department of Clinical Chemistry, Kuopio University Hospital, Finland.
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25
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Kaylor JJ, Risley JM. Synthesis of N4-(2-acetamido-2-deoxy-beta-D-glucopyranosyl)-L-asparagine analogues. n-Butyramide, 3-chloropropionamide, 3-aminopropionamide, and isovaleramide analogues. Carbohydr Res 2001; 331:439-44. [PMID: 11398986 DOI: 10.1016/s0008-6215(01)00057-x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The syntheses of four analogues of N4-(2-acetamido-2-deoxy-beta-D-glucopyranosyl)-L-asparagine are described. Activated carboxylic acids were reacted with 2-acetamido-2-deoxy-beta-D-glucopyranosylamine. n-Butyric anhydride gave N-(2-acetamido-2-deoxy-beta-D-glucopyranosyl)-n-butyramide. 3-Chloropropionic anhydride was synthesized from 3-chloropropionic acid and gave N-(2-acetamido-2-deoxy-beta-D-glucopyranosyl)-3-chloropropionamide. Equilibration of the latter with ammonium bicarbonate gave N1-(2-acetamido-2-deoxy-beta-D-glucopyranosyl)-3-aminopropionamide. Succinimidyl isovalerate was synthesized and gave N-(2-acetamido-2-deoxy-beta-D-glucopyranosyl)-isovaleramide.
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Affiliation(s)
- J J Kaylor
- Department of Chemistry, The University of North Carolina at Charlotte, 28223-0001, USA
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26
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Xia YQ, Risley JM. SYNTHESIS OFN4-(2-ACETAMIDO-2-DEOXY-β-D-GLUCOPYRANOSYL)-L-ASPARAGINE ANALOGUES.L-2-CHLORO-,L-2-BROMO-, ANDD,L-2-METHYLSUCCINAMIC ACID ANALOGUES. J Carbohydr Chem 2001. [DOI: 10.1081/car-100102542] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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27
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De Huang H, Risley JM. Synthesis of N4-(2-acetamido-2-deoxy-beta-D-glucopyranosyl)-L-asparagine analogues: succinamide, L-2-hydroxysuccinamide, and L-2-hydroxysuccinamic acid hydrazide analogues. Carbohydr Res 2000; 329:487-93. [PMID: 11128578 DOI: 10.1016/s0008-6215(00)00224-x] [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: 12/01/2022]
Abstract
The syntheses of three analogues of N4-(2-acetamido-2-deoxy-beta-D-glucopyranosyl)-L-asparagine are described. N-(2-Acetamido-2-deoxy-beta-D-glucopyranosyl)succinamide was synthesized by the reaction of pentafluorophenyl succinamate with 2-acetamido-2-deoxy-beta-D-glucopyranosylamine. 2-Acetamido-3,4,6-tri-O-acetyl-2-deoxy-beta-D-glucopyranosylamine was synthesized, and the complete assignment of the 1H NMR spectrum is given. Reaction of the protected beta-D-glycosylamine with L-malic acid chloralid in the presence of a coupling agent (EEDQ) gave N4-(2-acetamido-3,4,6-tri-O-acetyl-2-deoxy-beta-D-glucopyranosyl)-L-malamic acid chloralid that was deprotected two ways: (1) using ammonia, which gave N4-(2-acetamido-2-deoxy-beta-D-glucopyranosyl)-L-2-hydroxysuccinamide, and (2) using hydrazine, which gave N4-(2-acetamido-2-deoxy-1-D-glucopyranosyl)-L-2-hydroxysuccinamic acid hydrazide.
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Affiliation(s)
- H De Huang
- Department of Chemistry, University of North Carolina at Charlotte, 28223, USA
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