1
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Characterization of O-acetylation in sialoglycans by MALDI-MS using a combination of methylamidation and permethylation. Sci Rep 2017; 7:46206. [PMID: 28387371 PMCID: PMC5384204 DOI: 10.1038/srep46206] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2016] [Accepted: 03/13/2017] [Indexed: 12/12/2022] Open
Abstract
O-Acetylation of sialic acid in protein N-glycans is an important modification and can occur at either 4-, 7-, 8- or 9-position in various combinations. This modification is usually labile under alkaline reaction conditions. Consequently, a permethylation-based analytical method, which has been widely used in glycomics studies, is not suitable for profiling O-acetylation of sialic acids due to the harsh reaction conditions. Alternatively, methylamidation can be used for N-glycan analysis without affecting the base-labile modification of sialic acid. In this report, we applied both permethylation and methylamidation approaches to the analysis of O-acetylation in sialic acids. It has been demonstrated that methylamidation not only stabilizes sialic acids during MALDI processing but also allow for characterization of their O-acetylation pattern. In addition, LC-MS/MS experiments were carried out to distinguish between the O-acetylated glycans with potential isomeric structures. The repeatability of methylamidation was examined to evaluate the applicability of the approach to profiling of O-acetylation in sialic acids. In conclusion, the combination of methylamidation and permethylation methodology is a powerful MALDI-TOF MS-based tool for profiling O-acetylation in sialic acids applicable to screening of N-glycans.
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2
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Baumann AMT, Bakkers MJG, Buettner FFR, Hartmann M, Grove M, Langereis MA, de Groot RJ, Mühlenhoff M. 9-O-Acetylation of sialic acids is catalysed by CASD1 via a covalent acetyl-enzyme intermediate. Nat Commun 2015; 6:7673. [PMID: 26169044 PMCID: PMC4510713 DOI: 10.1038/ncomms8673] [Citation(s) in RCA: 79] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2015] [Accepted: 06/01/2015] [Indexed: 12/13/2022] Open
Abstract
Sialic acids, terminal sugars of glycoproteins and glycolipids, play important roles in development, cellular recognition processes and host–pathogen interactions. A common modification of sialic acids is 9-O-acetylation, which has been implicated in sialoglycan recognition, ganglioside biology, and the survival and drug resistance of acute lymphoblastic leukaemia cells. Despite many functional implications, the molecular basis of 9-O-acetylation has remained elusive thus far. Following cellular approaches, including selective gene knockout by CRISPR/Cas genome editing, we here show that CASD1—a previously identified human candidate gene—is essential for sialic acid 9-O-acetylation. In vitro assays with the purified N-terminal luminal domain of CASD1 demonstrate transfer of acetyl groups from acetyl-coenzyme A to CMP-activated sialic acid and formation of a covalent acetyl-enzyme intermediate. Our study provides direct evidence that CASD1 is a sialate O-acetyltransferase and serves as key enzyme in the biosynthesis of 9-O-acetylated sialoglycans. 9-O-Acetylation is one of the most common modifications of sialic acids, implicated in sialoglycan recognition and ganglioside biology. Here, the authors show that the key enzyme for the biosynthesis of 9-O-acetylated sialoglycans is CASD1, which uses CMP-activated sialic acid as acceptor substrate.![]()
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Affiliation(s)
- Anna-Maria T Baumann
- Institute of Cellular Chemistry, Hannover Medical School, D-30623 Hannover, Germany
| | - Mark J G Bakkers
- Virology Division, Department of Infectious Diseases and Immunology, Faculty of Veterinary Medicine, Utrecht University, 3584 CH Utrecht, The Netherlands
| | - Falk F R Buettner
- Institute of Cellular Chemistry, Hannover Medical School, D-30623 Hannover, Germany
| | - Maike Hartmann
- Institute of Cellular Chemistry, Hannover Medical School, D-30623 Hannover, Germany
| | - Melanie Grove
- Institute of Cellular Chemistry, Hannover Medical School, D-30623 Hannover, Germany
| | - Martijn A Langereis
- Virology Division, Department of Infectious Diseases and Immunology, Faculty of Veterinary Medicine, Utrecht University, 3584 CH Utrecht, The Netherlands
| | - Raoul J de Groot
- Virology Division, Department of Infectious Diseases and Immunology, Faculty of Veterinary Medicine, Utrecht University, 3584 CH Utrecht, The Netherlands
| | - Martina Mühlenhoff
- Institute of Cellular Chemistry, Hannover Medical School, D-30623 Hannover, Germany
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3
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Muthana SM, Campbell CT, Gildersleeve JC. Modifications of glycans: biological significance and therapeutic opportunities. ACS Chem Biol 2012; 7:31-43. [PMID: 22195988 DOI: 10.1021/cb2004466] [Citation(s) in RCA: 93] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Carbohydrates play a central role in a wide range of biological processes. As with nucleic acids and proteins, modifications of specific sites within the glycan chain can modulate a carbohydrate's overall biological function. For example, acylation, methylation, sulfation, epimerization, and phosphorylation can occur at various positions within a carbohydrate to modulate bioactivity. Therefore, there is significant interest in identifying discrete carbohydrate modifications and understanding their biological effects. Additionally, enzymes that catalyze those modifications and proteins that bind modified glycans provide numerous targets for therapeutic intervention. This review will focus on modifications of glycans that occur after the oligomer/polymer has been assembled, generally referred to as post-glycosylational modifications.
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Affiliation(s)
- Saddam M. Muthana
- Chemical Biology Laboratory, National Cancer Institute, NCI-Frederick, Frederick, Maryland 21702, United States
| | - Christopher T. Campbell
- Chemical Biology Laboratory, National Cancer Institute, NCI-Frederick, Frederick, Maryland 21702, United States
| | - Jeffrey C. Gildersleeve
- Chemical Biology Laboratory, National Cancer Institute, NCI-Frederick, Frederick, Maryland 21702, United States
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4
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Schauer R, Srinivasan GV, Wipfler D, Kniep B, Schwartz-Albiez R. O-Acetylated sialic acids and their role in immune defense. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2011; 705:525-48. [PMID: 21618128 PMCID: PMC7123180 DOI: 10.1007/978-1-4419-7877-6_28] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Affiliation(s)
- Roland Schauer
- Biochemisches Institut, Christian-Albrechts-Universität, Olshausenstr 40, D-24098 Kiel, Germany.
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5
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Liu X, Afonso L. Is permethylation strategy always applicable to protein N-glycosylation study?: A case study on the O-acetylation of sialic acid in fish serum glycans. Methods Mol Biol 2010; 600:259-268. [PMID: 19882134 DOI: 10.1007/978-1-60761-454-8_18] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
O-Acetylation is one of the major modifications of sialic acids that significantly alters biological properties of the parent molecule. These O-acetylated forms are components of the cellular membrane and can affect physiological and pathological responses. Understanding the role of N-glycans in physiology is of increasing relevance to cellular biologists in various disciplines who study glycoproteomics yet lack information regarding the function of the attached glycans. However, permethylation, the most common mass spectrometric analytical means, leads to the loss of O-linked acetyl groups in sialic acids. In this chapter, we demonstrated that O-acetylation of sialic acid in Atlantic salmon serum N-glycan can be well investigated by capillary electrophoresis-mass spectrometry.
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Affiliation(s)
- Xin Liu
- Institute for Biological Sciences, National Research Council Canada, Ottawa, Ontario, Canada
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6
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Bergfeld AK, Claus H, Lorenzen NK, Spielmann F, Vogel U, Mu Hlenhoff M. The polysialic acid-specific O-acetyltransferase OatC from Neisseria meningitidis serogroup C evolved apart from other bacterial sialate O-acetyltransferases. J Biol Chem 2008; 284:6-16. [PMID: 18986988 DOI: 10.1074/jbc.m807518200] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Neisseria meningitidis serogroup C is a major cause of bacterial meningitis and septicaemia. This human pathogen is protected by a capsule composed of alpha2,9-linked polysialic acid that represents an important virulence factor. In the majority of strains, the capsular polysaccharide is modified by O-acetylation at C-7 or C-8 of the sialic acid residues. The gene encoding the capsule modifying O-acetyltransferase is part of the capsule gene complex and shares no sequence similarities with other proteins. Here, we describe the purification and biochemical characterization of recombinant OatC. The enzyme was found as a homodimer, with the first 34 amino acids forming an efficient oligomerization domain that worked even in a different protein context. Using acetyl-CoA as donor substrate, OatC transferred acetyl groups exclusively onto polysialic acid joined by alpha2,9-linkages and did not act on free or CMP-activated sialic acid. Motif scanning revealed a nucleophile elbow motif (GXS286XGG), which is a hallmark of alpha/beta-hydrolase fold enzymes. In a comprehensive site-directed mutagenesis study, we identified a catalytic triad composed of Ser-286, Asp-376, and His-399. Consistent with a double-displacement mechanism common to alpha/beta-hydrolase fold enzymes, a covalent acetylenzyme intermediate was found. Together with secondary structure prediction highlighting an alpha/beta-hydrolase fold topology, our data provide strong evidence that OatC belongs to the alpha/beta-hydrolase fold family. This clearly distinguishes OatC from all other bacterial sialate O-acetyltransferases known so far because these are members of the hexapeptide repeat family, a class of acyltransferases that adopt a left-handed beta-helix fold and assemble into catalytic trimers.
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Affiliation(s)
- Anne K Bergfeld
- Department of Cellular Chemistry, Medical School Hannover, 30623 Hannover, Germany and the Institute for Hygiene and Microbiology, University of Wu¨rzburg, 97080 Wu¨rzburg, Germany
| | - Heike Claus
- Department of Cellular Chemistry, Medical School Hannover, 30623 Hannover, Germany and the Institute for Hygiene and Microbiology, University of Wu¨rzburg, 97080 Wu¨rzburg, Germany
| | - Nina K Lorenzen
- Department of Cellular Chemistry, Medical School Hannover, 30623 Hannover, Germany and the Institute for Hygiene and Microbiology, University of Wu¨rzburg, 97080 Wu¨rzburg, Germany
| | - Fabian Spielmann
- Department of Cellular Chemistry, Medical School Hannover, 30623 Hannover, Germany and the Institute for Hygiene and Microbiology, University of Wu¨rzburg, 97080 Wu¨rzburg, Germany
| | - Ulrich Vogel
- Department of Cellular Chemistry, Medical School Hannover, 30623 Hannover, Germany and the Institute for Hygiene and Microbiology, University of Wu¨rzburg, 97080 Wu¨rzburg, Germany
| | - Martina Mu Hlenhoff
- Department of Cellular Chemistry, Medical School Hannover, 30623 Hannover, Germany and the Institute for Hygiene and Microbiology, University of Wu¨rzburg, 97080 Wu¨rzburg, Germany.
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7
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Liu X, Afonso L, Altman E, Johnson S, Brown L, Li J. O-acetylation of sialic acids in N-glycans of Atlantic salmon (Salmo salar) serum is altered by handling stress. Proteomics 2008; 8:2849-57. [DOI: 10.1002/pmic.200701093] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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8
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Lrhorfi LA, Srinivasan GV, Schauer R. Properties and partial purification of sialate-O-acetyltransferase from bovine submandibular glands. Biol Chem 2007; 388:297-306. [PMID: 17338637 DOI: 10.1515/bc.2007.033] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
The O-acetylation of sialic acids in various positions is a frequent modification of these residues in glycoproteins and glycolipids of higher animals and some bacteria. Sialic acid O-acetylation is involved in the regulation of many cell biological and pathophysiological events. Since the properties and the structural and molecular genetic aspects of the eukaryotic sialate O-acetyltransferases are not yet known, we attempted to isolate the enzyme from bovine submandibular glands. O-Acetyltransferase was solubilised from its microsomal location with a zwitterionic detergent and enriched by approximately 50-fold in three steps, including affinity chromatography on coenzyme A. It exhibits a molecular mass of 150-160 kDa. Evidence was obtained for the putative existence of a low-molecular-mass, dialysable enzyme activator. The enzyme showed best activity with CMP-N-acetylneuraminic acid (CMP-Neu5Ac), followed by N-acetylneuraminic acid (Neu5Ac). These compounds, as well as AcCoA, have high affinity for both the microsome-bound and the partially purified O-acetyltransferase. CoA is a strong inhibitor. N-Acetyl-9-O-acetylneuraminic acid was found to be the main reaction product. No evidence was obtained for the involvement of an isomerase that might be responsible for the migration of O-acetyl groups within the sialic acid side chain.
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Affiliation(s)
- L Aicha Lrhorfi
- Biochemisches Institut, Christian-Albrechts-Universität, Olshausenstr. 40, D-24098 Kiel, Germany
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9
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Houliston RS, Endtz HP, Yuki N, Li J, Jarrell HC, Koga M, van Belkum A, Karwaski MF, Wakarchuk WW, Gilbert M. Identification of a sialate O-acetyltransferase from Campylobacter jejuni: demonstration of direct transfer to the C-9 position of terminalalpha-2, 8-linked sialic acid. J Biol Chem 2006; 281:11480-6. [PMID: 16481326 DOI: 10.1074/jbc.m512183200] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
We have identified a sialate O-acetyltransferase in the lipo-oligosaccharide biosynthesis locus of Campylobacter jejuni. Strains possessing this locus are known to produce sialylated outer core structures that mimic host gangliosides, and have been implicated in triggering the onset of Guillain-Barré syndrome. The acetyltransferase, which was cloned and expressed as a fusion construct in Escherichia coli, is soluble and homologous with members of the NodL-LacA-CysE family of O-acetyltransferases. This enzyme catalyzes the transfer of O-acetyl groups onto oligosaccharide-bound sialic acid, with a high specificity for terminal alpha2,8-linked residues. The modification is directed to C-9 and not C-7 as is believed to occur more commonly in other organisms. Despite their wide prevalence and importance in both eukaryotes and prokaryotes, this is the first report to describe the characterization of a purified sialate O-acetyltransferase.
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Affiliation(s)
- R Scott Houliston
- Institute for Biological Sciences, National Research Council Canada, Ottawa, Ontario K1A 0R6, Canada
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10
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Schauer R. Sialic acids: fascinating sugars in higher animals and man. ZOOLOGY 2006; 107:49-64. [PMID: 16351927 DOI: 10.1016/j.zool.2003.10.002] [Citation(s) in RCA: 306] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2003] [Accepted: 10/13/2003] [Indexed: 01/29/2023]
Abstract
Sialic acids are acidic monosaccharides, which are among the most important molecules of higher animals, and occur in some microorganisms. They are bound to complex carbohydrates and occupy prominent positions, especially in cell membranes. Their structural diversity is high and, correspondingly, the mechanisms for their biosynthesis are complex. Sialic acid substituents strongly influence the activity of catabolic enzymes, in particular the sialidases, and thus the turnover rate of glycoconjugates. These sugars are involved in manifold cell functions. Due to the surface location of the acidic molecules they shield macromolecules and cells from enzymatic and immunological attacks. But they also represent recognition sites for various physiological receptors as well as for toxins and microorganisms, and thus allow their colonization. Many viruses use sialic acids for the infection of cells. As sialic acids also play a decisive role in tumor biology they prove to be rather versatile molecules that modulate cell biological events in a sensitive way. It is discussed that their evolvement may have stimulated evolution and rendered organisms less vulnerable to environmental attacks. However, disturbance of their metabolism may cause diseases.
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Affiliation(s)
- Roland Schauer
- Biochemical Institute, University of Kiel, Olshausenstrasse 40, D-24098 Kiel, Germany.
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11
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Bandyopadhyay S, Mukherjee K, Chatterjee M, Bhattacharya DK, Mandal C. Detection of immune-complexed 9-O-acetylated sialoglycoconjugates in the sera of patients with pediatric acute lymphoblastic leukemia. J Immunol Methods 2004; 297:13-26. [PMID: 15777927 DOI: 10.1016/j.jim.2004.11.014] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2004] [Revised: 09/06/2004] [Accepted: 11/04/2004] [Indexed: 11/22/2022]
Abstract
Although childhood acute lymphoblastic leukemia (ALL) is highly responsive to chemotherapy, reliable techniques are needed to determine treatment outcome. Over expression of 9-O-acetylated sialoglycoconjugates (9-OAcSGs) on lymphoblasts and concomitant anti-9-OAcSGs was found to have a diagnostic and prognostic potential. However, the presence of circulatory immune-complexed antigens remains unknown. The present study was aimed to evaluate whether immune-complexed 9-OAcSGs can be harnessed for better disease management. Immune-complexed antigens were evaluated in ALL sera (n=262) by a Dot-blot using a 9-OAcSAalpha2-6GalNAc-specific lectin, Achatinin-H. Using three serum samples, the inter- and intra-assay imprecision was evaluated as 11-13% and 7-11%, respectively. The recovery of spiked 9-OAcSGs was 84.2-95.4%. The central 95% reference interval for immune-complexed 9-OAcSGs in normal human sera (NHS, n=144) was 2.9-3.4 mug/ml irrespective of sex and age. At disease presentation, the immune-complexed 9-OAcSGs were fivefold higher than NHS, decreased with remission induction and importantly, reappeared with clinical relapse. Sera from patients with other hematological disorders (n=86) showed negligible levels. The Dot-blot demonstrated the potential application of immune-complexed antigen as a disease-specific marker and its efficacy as a sensitive and specific method that could serve as an economical yet effective index for monitoring disease status.
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Affiliation(s)
- Suman Bandyopadhyay
- Immunobiology Division, Indian Institute of Chemical Biology, 4 Raja S.C. Mullick Road, Jadavpur, Kolkata-700 032, India
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12
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Pal S, Ghosh S, Bandyopadhyay S, Mandal C, Bandhyopadhyay S, Kumar Bhattacharya D, Mandal C. Differential expression of 9-O-acetylated sialoglycoconjugates on leukemic blasts: a potential tool for long-term monitoring of children with acute lymphoblastic leukemia. Int J Cancer 2004; 111:270-7. [PMID: 15197782 DOI: 10.1002/ijc.20246] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Earlier studies have demonstrated overexpression of 9-O-acetylated sialoglycoconjugates (9-O-AcSGs) on lymphoblasts, concomitant with high titers of anti-9-O-AcSG antibodies in childhood acute lymphoblastic leukemia (ALL). Our aim was to evaluate the correlation between expression of different 9-O-AcSGs during chemotherapeutic treatment. Accordingly, expression of 9-O-AcSGs on lymphoblasts of ALL patients (n = 70) were longitudinally monitored for 6 years (1997-2002), using Achatinin-H, a 9-O-acetylated sialic acid (9-O-AcSA) binding lectin with preferential affinity for 9-O-AcSGs with terminal 9-O-AcSA alpha 2-->6GalNAc. Western blot analysis of patients (n = 30) showed that 3 ALL-specific 9-O-AcSGs (90, 120 and 135 kDa) were induced at presentation; all these bands disappeared after treatment in patients (n = 22) who had disease-free survival. The 90 kDa band persisted in 8 patients who subsequently relapsed with reexpression of the 120 kDa band. FACS analysis revealed that at presentation (n = 70) 90.1 +/- 5.0% cells expressed 9-O-AcSGs, which decreased progressively with chemotherapy, remained <5% during clinical remission and reappeared in relapse (80 +/- 10%, n = 18). Early clearance of 9-O-AcSG(+) cells, during 4-8 weeks of treatment showed a good correlation with low risk of relapse. Sensitivity of detection of 9-O-AcSG(+) cells was 0.1%. Numbers of both high- and low-affinity binding sites were maximum at presentation, decreased with treatment and increased again in clinical relapse. We propose that close monitoring of 90 and 120 kDa 9-O-AcSGs may serve as a reliable index for long-term management of childhood ALL and merits therapeutic consideration.
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Affiliation(s)
- Santanu Pal
- Immunobiology Division, Indian Institute of Chemical Biology, Kolkata, India
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13
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Lewis AL, Nizet V, Varki A. Discovery and characterization of sialic acid O-acetylation in group B Streptococcus. Proc Natl Acad Sci U S A 2004; 101:11123-8. [PMID: 15263085 PMCID: PMC503750 DOI: 10.1073/pnas.0403010101] [Citation(s) in RCA: 122] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Group B Streptococcus (GBS) is the leading cause of human neonatal sepsis and meningitis. The GBS capsular polysaccharide is a major virulence factor and the active principle of vaccines in phase II trials. All GBS capsules have a terminal alpha 2-3-linked sialic acid [N-acetylneuraminic acid (Neu5Ac)], which interferes with complement-mediated killing. We show here that some of the Neu5Ac residues of the GBS type III capsule are O-acetylated at carbon position 7, 8, or 9, a major modification evidently missed in previous studies. Data are consistent with initial O-acetylation at position 7, and subsequent migration of the O-acetyl ester at positions 8 and 9. O-acetylation was also present on several other GBS serotypes (Ia, Ib, II, V, and VI). Deletion of the CMP-Neu5Ac synthase gene neuA by precise, in-frame allelic replacement gave intracellular accumulation of O-acetylated Neu5Ac, whereas overexpression markedly decreased O-acetylation. Given the known GBS Neu5Ac biosynthesis pathway, these data indicate that O-acetylation occurs on free Neu5Ac, competing with the CMP-Neu5Ac synthase. O-acetylation often generates immunogenic epitopes on bacterial capsular polysaccharides and can modulate human alternate pathway complement activation. Thus, our discovery has important implications for GBS pathogenicity, immunogenicity, and vaccine design.
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Affiliation(s)
- Amanda L Lewis
- Division of Biological Sciences, Glycobiology Research and Training Center, University of California at San Diego, La Jolla, CA 92093-0687, USA
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14
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Shen Y, Tiralongo J, Kohla G, Schauer R. Regulation of sialic acid O-acetylation in human colon mucosa. Biol Chem 2004; 385:145-52. [PMID: 15101557 DOI: 10.1515/bc.2004.033] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
The expression of O-acetylated sialic acids in human colonic mucins is developmentally regulated, and a reduction of O-acetylation has been found to be associated with the early stages of colorectal cancer. Despite this, however, little is known about the enzymatic process of sialic acid O-acetylation in human colonic mucosa. Recently, we have reported on a human colon sialate-7(9)-O-acetyltransferase capable of incorporating acetyl groups into sialic acids at the nucleotide-sugar level [Shen et al., Biol. Chem. 383 (2002), 307-317]. In this report, we show that the CMP-N-acetyl-neuraminic acid (CMP-Neu5Ac) and acetyl-CoA (AcCoA) transporters are critical components for the O-acetylation of CMP-Neu5Ac in Golgi lumen, with specific inhibition of either transporter leading to a reduction in the formation of CMP-5-N-acetyl-9-O-acetyl-neuraminic acid (CMP-Neu5,9Ac2). Moreover, the finding that 5-N-acetyl-9-O-acetyl-neuraminic acid (Neu5,9Ac2 could be transferred from neo-synthesised CMP-Neu5,9Ac2 to endogenous glycoproteins in the same Golgi vesicles, together with the observation that asialofetuin and asialo-human colon mucin are much better acceptors for Neu5,9Ac2 than asialo-bovine submandibular gland mucin, suggests that a sialyltransferase exists that preferentially utilises CMP-Neu5,9Ac2 as the donor substrate, transferring Neu5,9Ac2 to terminal Galbeta1,3(4)R- residues.
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Affiliation(s)
- Yanqin Shen
- Biochemisches Institut, Christian-Albrechts-Universität zu Kiel, Olshausenstr. 40, D-24098 Kiel, Germany
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15
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Ab initio calculations on various sialic acids provide valuable information about sialic acid-specific enzymes. ACTA ACUST UNITED AC 2004. [DOI: 10.1016/j.theochem.2004.01.013] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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16
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Shen Y, Kohla G, Lrhorfi AL, Sipos B, Kalthoff H, Gerwig GJ, Kamerling JP, Schauer R, Tiralongo J. O-acetylation and de-O-acetylation of sialic acids in human colorectal carcinoma. ACTA ACUST UNITED AC 2004; 271:281-90. [PMID: 14717696 DOI: 10.1046/j.1432-1033.2003.03927.x] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
A decrease in the level of O-acetylated sialic acids observed in colorectal carcinoma may lead to an increase in the expression of sialyl Lewis(X), a tumor-associated antigen, which is related to progression of colorectal cancer to metastasis. The underlying mechanism for this reduction is, however, not fully understood. Two enzymes are thought to be primarily responsible for the turnover of O-acetyl ester groups on sialic acids; sialate-O-acetyltransferase (OAT) and sialate-O-acetylesterase (OAE). We have previously reported the characterization of OAT activity from normal colon mucosa, which efficiently O-acetylates CMP-Neu5Ac exclusively in the Golgi apparatus prior to the action of sialyltransferase. In this report we describe the identification of a lysosomal and a cytosolic OAE activity in human colonic mucosa that specifically hydrolyses 9-O-acetyl groups on sialic acid. Utilizing matched resection margin and cancer tissue from colorectal carcinoma patients we provide strong evidence suggesting that the level of O-acetylated sialic acids present in normal and diseased human colon may be dependent on the relative activities of OAT to lysosomal OAE. Furthermore, we show that the level of free cytosolic Neu5,9Ac2 in human colon is regulated by the relative activity of the cytosolic OAE.
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Affiliation(s)
- Yanqin Shen
- Biochemisches Institut, Christian-Albrechts-Universität zu Kiel, Germany
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17
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Abstract
Viral O-acetylesterases were first identified in several viruses, including influenza C viruses and coronaviruses. These enzymes are capable of removing cellular receptors from the surface of target cells. Hence they are also known as "receptor destroying" enzymes. We have cloned and expressed several recombinant viral O-acetylesterases. These enzymes were secreted from Sf9 insect cells as chimeric proteins fused to eGFP. A purification scheme to isolate the recombinant O-acetylesterase of influenza C virus was developed. The recombinant enzymes derived from influenza C viruses specifically hydrolyze 9-O-acetylated sialic acids, while that of sialodacryoadenitis virus, a rat coronavirus related to mouse hepatitis virus, is specific for 4-O-acetylated sialic acid. The recombinant esterases were shown to specifically de-O-acetylate sialic acids on glycoconjugates. We have also expressed esterase knockout proteins of the influenza C virus hemagglutinin-esterase. The recombinant viral proteins can be used to unambiguously identify O-acetylated acids in a variety of assays.
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18
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Iwersen M, Dora H, Kohla G, Gasa S, Schauer R. Solubilisation and properties of the sialate-4-O-acetyltransferase from guinea pig liver. Biol Chem 2003; 384:1035-47. [PMID: 12956420 DOI: 10.1515/bc.2003.116] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
The O-acetylation of sialic acids turns out to be one of the most important modifications that influence the diverse biological and pathophysiological properties of glycoconjugates in animals and microorganisms. To understand the functions of this esterification, knowledge of the properties, structures and regulation of expression of the enzymes involved is essential. Attempts to solubilise, purify or clone the gene of one of the sialate-O-acetyltransferases have failed so far. Here we report on the solubilisation of the sialate-4-O-acetyltransferase from guinea pig liver, the first and essential step in the purification and molecular characterisation of this enzyme, by the zwitterionic detergent CHAPS. This enzyme O-acetylates sialic acids at C-4 both free and bound to oligosaccharides, glycoproteins and glycolipids with varying activity, however, gangliosides proved to be the best substrates. Correspondingly, a rapid enzyme test was elaborated using the ganglioside GD3. The soluble O-acetyltransferase maximally operated at 30 degrees C, pH 5.6, and 50-70 mM KCl and K2HPO4 concentrations. The Km values were 3.6 microM for AcCoA and 1.2 microM for GD3. CoA inhibits the enzyme with a Ki value of 14.8 microM. A most important discovery enabling further enzyme purification is its need for an unknown low molecular mass and heat-stable cofactor that can be separated from the crude enzyme preparation by 30 kDa ultrafiltration.
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Affiliation(s)
- Matthias Iwersen
- Biochemisches Institut, Christian-Albrechts-Universität, Olshausenstr. 40, D-24098 Kiel, Germany
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Satake H, Chen HY, Varki A. Genes modulated by expression of GD3 synthase in Chinese hamster ovary cells. Evidence that the Tis21 gene is involved in the induction of GD3 9-O-acetylation. J Biol Chem 2003; 278:7942-8. [PMID: 12493756 DOI: 10.1074/jbc.m210565200] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
9-O-Acetylation is a common sialic acid modification, expressed in a developmentally regulated and tissue/cell type-specific manner. The relevant 9-O-acetyltransferase(s) have not been isolated or cloned; nor have mechanisms for their regulation been elucidated. We previously showed that transfection of the GD3 synthase (ST8Sia-I) gene into Chinese hamster ovary (CHO)-K1 cells gave expression of not only the disialoganglioside GD3 but also 9-O-acetyl-GD3. We now use differential display PCR between wild type CHO-K1 cells and clones stably expressing GD3 synthase (CHO-GD3 cells) to detect any increased expression of other genes and explore the possible induction of a 9-O-acetyltransferase. The four CHO mRNAs showing major up-regulation were homologous to VCAM-1, Tis21, the KC-protein-like protein, and a functionally unknown type II transmembrane protein. A moderate increase in expression of the FxC1 and SPR-1 genes was also seen. Interestingly, these are different from genes observed by others to be up-regulated after transfection of GD3 synthase into a neuroblastoma cell line. We also isolated a CHO-GD3 mutant lacking 9-O-acetyl-GD3 following chemical mutagenesis (CHO-GD3-OAc(-)). Analysis of the above differential display PCR-derived genes in these cells showed that expression of Tis21 was selectively reduced. Transfection of a mouse Tis21 cDNA into the CHO-GD3-OAc(-) mutant cells restored 9-O-acetyl-GD3 expression. Since the only major gangliosides expressed by CHO-GD3 cells are GD3 and 9-O-acetyl-GD3 (in addition to GM3, the predominant ganglioside type in wild-type CHO-K1 cells), we conclude that GD3 enhances its own 9-O-acetylation via induction of Tis21. This is the first known nuclear inducible factor for 9-O-acetylation and also the first proof that 9-O-acetylation can be directly regulated by GD3 synthase. Finally, transfection of CHO-GD3-OAc(-) mutant cells with ST6Gal-I induced 9-O-acetylation specifically on sialylated N-glycans, in a manner similar to wild-type cells. This indicates separate machineries for 9-O-acetylation on alpha2-8-linked sialic acids of gangliosides and on alpha2-6-linked sialic acids on N-glycans.
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Affiliation(s)
- Honoo Satake
- Glycobiology Research and Training Center, Department of Medicine, University of California, San Diego, La Jolla 92093-0687, USA
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Malisan F, Franchi L, Tomassini B, Ventura N, Condò I, Rippo MR, Rufini A, Liberati L, Nachtigall C, Kniep B, Testi R. Acetylation suppresses the proapoptotic activity of GD3 ganglioside. J Exp Med 2002; 196:1535-41. [PMID: 12486096 PMCID: PMC2196066 DOI: 10.1084/jem.20020960] [Citation(s) in RCA: 84] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022] Open
Abstract
GD3 synthase is rapidly activated in different cell types after specific apoptotic stimuli. De novo synthesized GD3 accumulates and contributes to the apoptotic program by relocating to mitochondrial membranes and inducing the release of apoptogenic factors. We found that sialic acid acetylation suppresses the proapoptotic activity of GD3. In fact, unlike GD3, 9-O-acetyl-GD3 is completely ineffective in inducing cytochrome c release and caspase-9 activation on isolated mitochondria and fails to induce the collapse of mitochondrial transmembrane potential and cellular apoptosis. Moreover, cells which are resistant to the overexpression of the GD3 synthase, actively convert de novo synthesized GD3 to 9-O-acetyl-GD3. The coexpression of GD3 synthase with a viral 9-O-acetyl esterase, which prevents 9-O-acetyl-GD3 accumulation, reconstitutes GD3 responsiveness and apoptosis. Finally, the expression of the 9-O-acetyl esterase is sufficient to induce apoptosis of glioblastomas which express high levels of 9-O-acetyl-GD3. Thus, sialic acid acetylation critically controls the proapoptotic activity of GD3.
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Affiliation(s)
- Florence Malisan
- Laboratory of Immunology and Signal Transduction, Department of Experimental Medicine and Biochemical Sciences, University of Rome Tor Vergata, 00133 Rome, Italy
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