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Cummings RD. A periodic table of monosaccharides. Glycobiology 2024; 34:cwad088. [PMID: 37935401 DOI: 10.1093/glycob/cwad088] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2023] [Revised: 10/23/2023] [Accepted: 10/31/2023] [Indexed: 11/09/2023] Open
Abstract
It is important to recognize the great diversity of monosaccharides commonly encountered in animals, plants, and microbes, as well as to organize them in a visually interesting style that also emphasizes their similarities and relatedness. This article discusses the nature of building blocks, monosaccharides, and monosaccharide derivatives-terms commonly used in discussing "glycomolecules" found in nature. To aid in awareness of monosaccharide diversity, here is presented a Periodic Table of Monosaccharides. The rationale is given for construction of the Table and the selection of 103 monosaccharides, which is largely based on those presented in the KEGG and SNFG websites of monosaccharides, and includes room to enlarge as new discoveries are made. The Table should have educational value and is intended to capture the attention and foster imagination of those not very familiar with glycosciences, and encourage researchers to delve deeper into this fascinating area.
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Affiliation(s)
- Richard D Cummings
- Department of Surgery, Beth Israel Deaconess Medical Center, Harvard Medical School, CLS 11087-3 Blackfan Circle, Boston, MA 02115, United States
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2
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Barnard KN, Alford-Lawrence BK, Buchholz DW, Wasik BR, LaClair JR, Yu H, Honce R, Ruhl S, Pajic P, Daugherity EK, Chen X, Schultz-Cherry SL, Aguilar HC, Varki A, Parrish CR. Modified Sialic Acids on Mucus and Erythrocytes Inhibit Influenza A Virus Hemagglutinin and Neuraminidase Functions. J Virol 2020; 94:e01567-19. [PMID: 32051275 PMCID: PMC7163148 DOI: 10.1128/jvi.01567-19] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2019] [Accepted: 02/04/2020] [Indexed: 12/13/2022] Open
Abstract
Sialic acids (Sia) are the primary receptors for influenza viruses and are widely displayed on cell surfaces and in secreted mucus. Sia may be present in variant forms that include O-acetyl modifications at C-4, C-7, C-8, and C-9 positions and N-acetyl or N-glycolyl at C-5. They can also vary in their linkages, including α2-3 or α2-6 linkages. Here, we analyze the distribution of modified Sia in cells and tissues of wild-type mice or in mice lacking CMP-N-acetylneuraminic acid hydroxylase (CMAH) enzyme, which synthesizes N-glycolyl (Neu5Gc) modifications. We also examined the variation of Sia forms on erythrocytes and in saliva from different animals. To determine the effect of Sia modifications on influenza A virus (IAV) infection, we tested for effects on hemagglutinin (HA) binding and neuraminidase (NA) cleavage. We confirmed that 9-O-acetyl, 7,9-O-acetyl, 4-O-acetyl, and Neu5Gc modifications are widely but variably expressed in mouse tissues, with the highest levels detected in the respiratory and gastrointestinal (GI) tracts. Secreted mucins in saliva and surface proteins of erythrocytes showed a high degree of variability in display of modified Sia between different species. IAV HAs from different virus strains showed consistently reduced binding to both Neu5Gc- and O-acetyl-modified Sia; however, while IAV NAs were inhibited by Neu5Gc and O-acetyl modifications, there was significant variability between NA types. The modifications of Sia in mucus may therefore have potent effects on the functions of IAV and may affect both pathogens and the normal flora of different mucosal sites.IMPORTANCE Sialic acids (Sia) are involved in numerous different cellular functions and are receptors for many pathogens. Sia come in chemically modified forms, but we lack a clear understanding of how they alter interactions with microbes. Here, we examine the expression of modified Sia in mouse tissues, on secreted mucus in saliva, and on erythrocytes, including those from IAV host species and animals used in IAV research. These Sia forms varied considerably among different animals, and their inhibitory effects on IAV NA and HA activities and on bacterial sialidases (neuraminidases) suggest a host-variable protective role in secreted mucus.
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Affiliation(s)
- Karen N Barnard
- Baker Institute for Animal Health, Department of Microbiology and Immunology, College of Veterinary Medicine, Cornell University, Ithaca, New York, USA
| | - Brynn K Alford-Lawrence
- Baker Institute for Animal Health, Department of Microbiology and Immunology, College of Veterinary Medicine, Cornell University, Ithaca, New York, USA
| | - David W Buchholz
- Department of Microbiology and Immunology, College of Veterinary Medicine, Cornell University, Ithaca, New York, USA
| | - Brian R Wasik
- Baker Institute for Animal Health, Department of Microbiology and Immunology, College of Veterinary Medicine, Cornell University, Ithaca, New York, USA
| | - Justin R LaClair
- Baker Institute for Animal Health, Department of Microbiology and Immunology, College of Veterinary Medicine, Cornell University, Ithaca, New York, USA
| | - Hai Yu
- Department of Chemistry, University of California-Davis, Davis, California, USA
| | - Rebekah Honce
- Department of Infectious Diseases, St. Jude Children's Research Hospital, Memphis, Tennessee, USA
- Department of Microbiology, Immunology, and Biochemistry, University of Tennessee Health Science Center, Memphis, Tennessee, USA
| | - Stefan Ruhl
- Department of Oral Biology, University at Buffalo, Buffalo, New York, USA
| | - Petar Pajic
- Department of Oral Biology, University at Buffalo, Buffalo, New York, USA
| | - Erin K Daugherity
- Center for Animal Resources and Education, Cornell University, Ithaca, New York, USA
| | - Xi Chen
- Department of Chemistry, University of California-Davis, Davis, California, USA
| | - Stacey L Schultz-Cherry
- Department of Infectious Diseases, St. Jude Children's Research Hospital, Memphis, Tennessee, USA
| | - Hector C Aguilar
- Department of Microbiology and Immunology, College of Veterinary Medicine, Cornell University, Ithaca, New York, USA
| | - Ajit Varki
- Glycobiology Research and Training Center, University of California, San Diego, California, USA
| | - Colin R Parrish
- Baker Institute for Animal Health, Department of Microbiology and Immunology, College of Veterinary Medicine, Cornell University, Ithaca, New York, USA
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Post-Glycosylation Modification of Sialic Acid and Its Role in Virus Pathogenesis. Vaccines (Basel) 2019; 7:vaccines7040171. [PMID: 31683930 PMCID: PMC6963189 DOI: 10.3390/vaccines7040171] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2019] [Revised: 10/08/2019] [Accepted: 10/23/2019] [Indexed: 01/20/2023] Open
Abstract
Sialic acids are a family of nine carbon keto-aldononulosonic acids presented at the terminal ends of glycans on cellular membranes. α-Linked sialoglycoconjugates often undergo post-glycosylation modifications, among which O-acetylation of N-acetyl neuraminic acid (Neu5Ac) is the most common in mammalian cells. Isoforms of sialic acid are critical determinants of virus pathogenesis. To date, the focus of viral receptor-mediated attachment has been on Neu5Ac. O-Acetylated Neu5Acs have been largely ignored as receptor determinants of virus pathogenesis, although it is ubiquitous across species. Significantly, the array of structures resulting from site-specific O-acetylation by sialic acid O-acetyltransferases (SOATs) provides a means to examine specificity of viral binding to host cells. Specifically, C4 O-acetylated Neu5Ac can influence virus pathogenicity. However, the biological implications of only O-acetylated Neu5Ac at C7-9 have been explored extensively. This review will highlight the biological significance, extraction methods, and synthetic modifications of C4 O-acetylated Neu5Ac that may provide value in therapeutic developments and targets to prevent virus related diseases.
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Abstract
Sialic acids are cytoprotectors, mainly localized on the surface of cell membranes with multiple and outstanding cell biological functions. The history of their structural analysis, occurrence, and functions is fascinating and described in this review. Reports from different researchers on apparently similar substances from a variety of biological materials led to the identification of a 9-carbon monosaccharide, which in 1957 was designated "sialic acid." The most frequently occurring member of the sialic acid family is N-acetylneuraminic acid, followed by N-glycolylneuraminic acid and O-acetylated derivatives, and up to now over about 80 neuraminic acid derivatives have been described. They appeared first in the animal kingdom, ranging from echinoderms up to higher animals, in many microorganisms, and are also expressed in insects, but are absent in higher plants. Sialic acids are masks and ligands and play as such dual roles in biology. Their involvement in immunology and tumor biology, as well as in hereditary diseases, cannot be underestimated. N-Glycolylneuraminic acid is very special, as this sugar cannot be expressed by humans, but is a xenoantigen with pathogenetic potential. Sialidases (neuraminidases), which liberate sialic acids from cellular compounds, had been known from very early on from studies with influenza viruses. Sialyltransferases, which are responsible for the sialylation of glycans and elongation of polysialic acids, are studied because of their significance in development and, for instance, in cancer. As more information about the functions in health and disease is acquired, the use of sialic acids in the treatment of diseases is also envisaged.
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Affiliation(s)
- Roland Schauer
- Biochemisches Institut, Christian-Albrechts-Universität zu Kiel, Kiel, Germany.
| | - Johannis P Kamerling
- Bijvoet Center for Biomolecular Research, Utrecht University, Utrecht, The Netherlands.
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Wasik BR, Barnard KN, Ossiboff RJ, Khedri Z, Feng KH, Yu H, Chen X, Perez DR, Varki A, Parrish CR. Distribution of O-Acetylated Sialic Acids among Target Host Tissues for Influenza Virus. mSphere 2017; 2:e00379-16. [PMID: 28904995 PMCID: PMC5588038 DOI: 10.1128/msphere.00379-16] [Citation(s) in RCA: 46] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2016] [Accepted: 08/17/2017] [Indexed: 12/30/2022] Open
Abstract
Sialic acids (Sias) are important glycans displayed on the cells and tissues of many different animals and are frequent targets for binding and modification by pathogens, including influenza viruses. Influenza virus hemagglutinins bind Sias during the infection of their normal hosts, while the encoded neuraminidases and/or esterases remove or modify the Sia to allow virion release or to prevent rebinding. Sias naturally occur in a variety of modified forms, and modified Sias can alter influenza virus host tropisms through their altered interactions with the viral glycoproteins. However, the distribution of modified Sia forms and their effects on pathogen-host interactions are still poorly understood. Here we used probes developed from viral Sia-binding proteins to detect O-acetylated (4-O-acetyl, 9-O-acetyl, and 7,9-O-acetyl) Sias displayed on the tissues of some natural or experimental hosts for influenza viruses. These modified Sias showed highly variable displays between the hosts and tissues examined. The 9-O-acetyl (and 7,9-) modified Sia forms were found on cells and tissues of many hosts, including mice, humans, ferrets, guinea pigs, pigs, horses, dogs, as well as in those of ducks and embryonated chicken egg tissues and membranes, although in variable amounts. The 4-O-acetyl Sias were found in the respiratory tissues of fewer animals, being primarily displayed in the horse and guinea pig, but were not detected in humans or pigs. The results suggest that these Sia variants may influence virus tropisms by altering and selecting their cell interactions. IMPORTANCE Sialic acids (Sias) are key glycans that control or modulate many normal cell and tissue functions while also interacting with a variety of pathogens, including many different viruses. Sias are naturally displayed in a variety of different forms, with modifications at several positions that can alter their functional interactions with pathogens. In addition, Sias are often modified or removed by enzymes such as host or pathogen esterases or sialidases (neuraminidases), and Sia modifications can alter those enzymatic activities to impact pathogen infections. Sia chemical diversity in different hosts and tissues likely alters the pathogen-host interactions and influences the outcome of infection. Here we explored the display of 4-O-acetyl, 9-O-acetyl, and 7,9-O-acetyl modified Sia forms in some target tissues for influenza virus infection in mice, humans, birds, guinea pigs, ferrets, swine, horses, and dogs, which encompass many natural and laboratory hosts of those viruses.
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Affiliation(s)
- Brian R. Wasik
- Department of Microbiology and Immunology, Baker Institute for Animal Health, College of Veterinary Medicine, Cornell University, Ithaca, New York, USA
| | - Karen N. Barnard
- Department of Microbiology and Immunology, Baker Institute for Animal Health, College of Veterinary Medicine, Cornell University, Ithaca, New York, USA
| | - Robert J. Ossiboff
- Department of Population Medicine and Diagnostic Sciences, Animal Health Diagnostic Center, College of Veterinary Medicine, Cornell University, Ithaca, New York, USA
| | - Zahra Khedri
- Glycobiology Research and Training Center, University of California, San Diego, La Jolla, California, USA
| | - Kurtis H. Feng
- Department of Microbiology and Immunology, Baker Institute for Animal Health, College of Veterinary Medicine, Cornell University, Ithaca, New York, USA
| | - Hai Yu
- Department of Chemistry, University of California, Davis, Davis, California, USA
| | - Xi Chen
- Department of Chemistry, University of California, Davis, Davis, California, USA
| | - Daniel R. Perez
- Department of Population Health, Poultry Diagnostic and Research Center, College of Veterinary Medicine, University of Georgia, Athens, Georgia, USA
| | - Ajit Varki
- Glycobiology Research and Training Center, University of California, San Diego, La Jolla, California, USA
| | - Colin R. Parrish
- Department of Microbiology and Immunology, Baker Institute for Animal Health, College of Veterinary Medicine, Cornell University, Ithaca, New York, USA
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6
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Wasik BR, Barnard KN, Parrish CR. Effects of Sialic Acid Modifications on Virus Binding and Infection. Trends Microbiol 2016; 24:991-1001. [PMID: 27491885 PMCID: PMC5123965 DOI: 10.1016/j.tim.2016.07.005] [Citation(s) in RCA: 73] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2016] [Revised: 07/12/2016] [Accepted: 07/14/2016] [Indexed: 12/29/2022]
Abstract
Sialic acids (Sias) are abundantly displayed on the surfaces of vertebrate cells, and particularly on all mucosal surfaces. Sias interact with microbes of many types, and are the targets of specific recognition by many different viruses. They may mediate virus binding and infection of cells, or alternatively can act as decoy receptors that bind virions and block virus infection. These nine-carbon backbone monosaccharides naturally occur in many different modified forms, and are attached to underlying glycans through varied linkages, creating significant diversity in the pathogen receptor forms. Here we review the current knowledge regarding the distribution of modified Sias in different vertebrate hosts, tissues, and cells, their effects on viral pathogens where those have been examined, and outline unresolved questions. Sialic acids (Sias) are components of cell-surface glycoproteins and glycolipids, as well as secreted glycoproteins and milk oligosaccharides. Sias play important roles in cell signaling, development, and host–pathogen interactions. Cellular enzymes can modify Sias, yet how modifications vary between tissues and hosts has not been fully elucidated. Many viruses use Sias as receptors, with different modifications aiding or inhibiting virus infection. How modified Sias influence viral protein evolution and determine host/tissue tropism are poorly understood, and are important areas of research. New advances in molecular glycobiology using pathogen proteins to detect varied forms allows for improved study of modified Sias that have otherwise proven difficult to isolate. This opens new avenues of inquiry for virology, as well as host interactions with bacterial and eukaryotic pathogens.
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Affiliation(s)
- Brian R Wasik
- Baker Institute for Animal Health, Department of Microbiology and Immunology, College of Veterinary Medicine, Cornell University, Ithaca, NY 14853, USA.
| | - Karen N Barnard
- Baker Institute for Animal Health, Department of Microbiology and Immunology, College of Veterinary Medicine, Cornell University, Ithaca, NY 14853, USA
| | - Colin R Parrish
- Baker Institute for Animal Health, Department of Microbiology and Immunology, College of Veterinary Medicine, Cornell University, Ithaca, NY 14853, USA
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7
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Urashima T, Inamori H, Fukuda K, Saito T, Messer M, Oftedal OT. 4-O-Acetyl-sialic acid (Neu4,5Ac2) in acidic milk oligosaccharides of the platypus (Ornithorhynchus anatinus) and its evolutionary significance. Glycobiology 2015; 25:683-97. [DOI: 10.1093/glycob/cwv010] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2014] [Accepted: 01/13/2015] [Indexed: 12/15/2022] Open
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Park SS, Gervay-Hague J. Synthesis of partially O-acetylated N-acetylneuraminic acid using regioselective silyl exchange technology. Org Lett 2014; 16:5044-7. [PMID: 25247390 PMCID: PMC4184446 DOI: 10.1021/ol502389g] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
![]()
Postglycosylation acetylation of
sialic acid imparts unique roles
to sialoglycoconjugates in mammalian immune response making structural
and functional understanding of these analogues important. Five partially O-acetylated Neu5Ac analogues have been synthesized. Reaction
of per-O-silylated Neu5Ac ester with AcOH and Ac2O in pyridine promotes regioselective silyl ether/acetate
exchange in the following order: C4 (2°) > C9 (1°) > C8 (2°) > C2 (anomeric).
Subsequent hydrogenolysis affords the corresponding sialic acid analogues
as useful chemical biology tools.
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Affiliation(s)
- Simon S Park
- Department of Chemistry, University of California, Davis , One Shields Avenue, Davis, California 95616, United States
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Oftedal OT, Nicol SC, Davies NW, Sekii N, Taufik E, Fukuda K, Saito T, Urashima T. Can an ancestral condition for milk oligosaccharides be determined? Evidence from the Tasmanian echidna (Tachyglossus aculeatus setosus). Glycobiology 2014; 24:826-39. [DOI: 10.1093/glycob/cwu041] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Affiliation(s)
- Olav T Oftedal
- Smithsonian Environmental Research Center, Smithsonian Institution, Edgewater, MD 21037, USA
| | | | - Noel W Davies
- Central Science Laboratory, University of Tasmania, Hobart, TAS 7001, Australia
| | - Nobuhiro Sekii
- Graduate School of Animal and Food Hygiene, Obihiro University of Agriculture and Veterinary Medicine, Obihiro, Hokkaido 080-8555, Japan
| | - Epi Taufik
- Graduate School of Animal and Food Hygiene, Obihiro University of Agriculture and Veterinary Medicine, Obihiro, Hokkaido 080-8555, Japan
| | - Kenji Fukuda
- Graduate School of Animal and Food Hygiene, Obihiro University of Agriculture and Veterinary Medicine, Obihiro, Hokkaido 080-8555, Japan
| | - Tadao Saito
- Graduate School of Agriculture, Tohoku University, Sendai, Miyagi 981-8555, Japan
| | - Tadasu Urashima
- Graduate School of Animal and Food Hygiene, Obihiro University of Agriculture and Veterinary Medicine, Obihiro, Hokkaido 080-8555, Japan
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Romero-Ramírez L, García-Álvarez I, Campos-Olivas R, Gilbert M, Goneau MF, Fernández-Mayoralas A, Nieto-Sampedro M. Specific synthesis of neurostatin and gangliosides O-acetylated in the outer sialic acids using a sialate transferase. PLoS One 2012; 7:e49983. [PMID: 23226505 PMCID: PMC3513307 DOI: 10.1371/journal.pone.0049983] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2012] [Accepted: 10/16/2012] [Indexed: 11/28/2022] Open
Abstract
Gangliosides are sialic acid containing glycosphingolipids, commonly found on the outer leaflet of the plasma membrane. O-acetylation of sialic acid hydroxyl groups is one of the most common modifications in gangliosides. Studies on the biological activity of O-acetylated gangliosides have been limited by their scarcity in nature. This comparatively small change in ganglioside structure causes major changes in their physiological properties. When the ganglioside GD1b was O-acetylated in the outer sialic acid, it became the potent inhibitor of astroblast and astrocytoma proliferation called Neurostatin. Although various chemical and enzymatic methods to O-acetylate commercial gangliosides have been described, O-acetylation was nonspecific and produced many side-products that reduced the yield. An enzyme with O-acetyltransferase activity (SOAT) has been previously cloned from the bacteria Campylobacter jejuni. This enzyme catalyzed the acetylation of oligosaccharide-bound sialic acid, with high specificity for terminal alpha-2,8-linked residues. Using this enzyme and commercial gangliosides as starting material, we have specifically O-acetylated the gangliosides' outer sialic acids, to produce the corresponding gangliosides specifically O-acetylated in the sialic acid bound in alpha-2,3 and alpha-2,8 residues. We demonstrate here that O-acetylation occurred specifically in the C-9 position of the sialic acid. In summary, we present a new method of specific O-acetylation of ganglioside sialic acids that permits the large scale preparation of these modified glycosphingolipids, facilitating both, the study of their mechanism of antitumoral action and their use as therapeutic drugs for treating glioblastoma multiform (GBM) patients.
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Sialic acid metabolism and sialyltransferases: natural functions and applications. Appl Microbiol Biotechnol 2012; 94:887-905. [PMID: 22526796 DOI: 10.1007/s00253-012-4040-1] [Citation(s) in RCA: 187] [Impact Index Per Article: 15.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2012] [Revised: 03/16/2012] [Accepted: 03/16/2012] [Indexed: 12/17/2022]
Abstract
Sialic acids are a family of negatively charged monosaccharides which are commonly presented as the terminal residues in glycans of the glycoconjugates on eukaryotic cell surface or as components of capsular polysaccharides or lipooligosaccharides of some pathogenic bacteria. Due to their important biological and pathological functions, the biosynthesis, activation, transfer, breaking down, and recycle of sialic acids are attracting increasing attention. The understanding of the sialic acid metabolism in eukaryotes and bacteria leads to the development of metabolic engineering approaches for elucidating the important functions of sialic acid in mammalian systems and for large-scale production of sialosides using engineered bacterial cells. As the key enzymes in biosynthesis of sialylated structures, sialyltransferases have been continuously identified from various sources and characterized. Protein crystal structures of seven sialyltransferases have been reported. Wild-type sialyltransferases and their mutants have been applied with or without other sialoside biosynthetic enzymes for producing complex sialic acid-containing oligosaccharides and glycoconjugates. This mini-review focuses on current understanding and applications of sialic acid metabolism and sialyltransferases.
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Abstract
Sialic acids have a pivotal functional impact in many biological interactions such as virus attachment, cellular adhesion, regulation of proliferation, and apoptosis. A common modification of sialic acids is O-acetylation. O-Acetylated sialic acids occur in bacteria and parasites and are also receptor determinants for a number of viruses. Moreover, they have important functions in embryogenesis, development, and immunological processes. O-Acetylated sialic acids represent cancer markers, as shown for acute lymphoblastic leukemia, and they are known to play significant roles in the regulation of ganglioside-mediated apoptosis. Expression of O-acetylated sialoglycans is regulated by sialic acid-specific O-acetyltransferases and O-acetylesterases. Recent developments in the identification of the enigmatic sialic acid-specific O-acetyltransferase are discussed.
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Affiliation(s)
- Chitra Mandal
- Cancer and Cell Biology, Council of Scientific and Industrial Research - Indian Institute of Chemical Biology, 4 Raja S.C. Mallick Road, Kolkata, 700 032 India
| | - Reinhard Schwartz-Albiez
- Department of Translational Immunology, German Cancer Research Center, 69120 Heidelberg, Germany
| | - Reinhard Vlasak
- Department of Molecular Biology, University Salzburg, Billrothstr 11, 5020 Salzburg, Austria
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Arming S, Wipfler D, Mayr J, Merling A, Vilas U, Schauer R, Schwartz-Albiez R, Vlasak R. The human Cas1 protein: a sialic acid-specific O-acetyltransferase? Glycobiology 2011; 21:553-64. [PMID: 20947662 PMCID: PMC7108626 DOI: 10.1093/glycob/cwq153] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
Sialic acids are important sugars at the reducing end of glycoproteins and glycolipids. They are among many other functions involved in cell-cell interactions, host-pathogen recognition and the regulation of serum half-life of glycoproteins. An important modification of sialic acids is O-acetylation, which can alter or mask the biological properties of the parent sialic acid molecule. The nature of mammalian sialate-O-acetyltransferases (EC 2.3.1.45) involved in their biosynthesis is still unknown. We have identified the human CasD1 (capsule structure1 domain containing 1) gene as a candidate to encode the elusive enzyme. The human CasD1 gene encodes a protein with a serine-glycine-asparagine-histidine hydrolase domain and a hydrophobic transmembrane domain. Expression of the Cas1 protein tagged with enhanced green fluorescent protein in mammalian and insect cells directed the protein to the medial and trans-cisternae of the Golgi. Overexpression of the Cas1 protein in combination with α-N-acetyl-neuraminide α-2,8-sialyltransferase 1 (GD3 synthase) resulted in an up to 40% increased biosynthesis of 7-O-acetylated ganglioside GD3. By quantitative real-time polymerase chain reaction, we found up to 5-fold increase in CasD1 mRNA in tumor cells overexpressing O-Ac-GD3. CasD1-specific small interfering RNA reduced O-acetylation in tumor cells. These results suggest that the human Cas1 protein is directly involved in O-acetylation of α2-8-linked sialic acids.
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Affiliation(s)
- Sigrid Arming
- Department of Molecular Biology, University Salzburg, Austria
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14
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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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15
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Eleutério I, Streicher H. Synthesis of Substrates for the Characterisation of Sialate-O-Acetyltransferases. JOURNAL OF CHEMICAL RESEARCH 2010. [DOI: 10.3184/030823410x12862035050403] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The synthesis of a series of α- and β-configured sialosides using a Koenigs–Knorr methodology is described. The target compounds can serve as substrates for the investigation of biologically relevant sialate- O-acetyltransferase activity.
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Affiliation(s)
- Inês Eleutério
- Department of Chemistry and Biochemistry, University of Sussex, Brighton BN1 9QG, UK
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16
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Mittal R, Peak-Chew SY, Sade RS, Vallis Y, McMahon HT. The acetyltransferase activity of the bacterial toxin YopJ of Yersinia is activated by eukaryotic host cell inositol hexakisphosphate. J Biol Chem 2010; 285:19927-34. [PMID: 20430892 PMCID: PMC2888404 DOI: 10.1074/jbc.m110.126581] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
Plague, one of the most devastating diseases in human history, is caused by the bacterium Yersinia pestis. The bacteria use a syringe-like macromolecular assembly to secrete various toxins directly into the host cells they infect. One such Yersinia outer protein, YopJ, performs the task of dampening innate immune responses in the host by simultaneously inhibiting the MAPK and NFκB signaling pathways. YopJ catalyzes the transfer of acetyl groups to serine, threonine, and lysine residues on target proteins. Acetylation of serine and threonine residues prevents them from being phosphorylated thereby preventing the activation of signaling molecules on which they are located. In this study, we describe the requirement of a host-cell factor for full activation of the acetyltransferase activity of YopJ and identify this activating factor to be inositol hexakisphosphate (IP6). We extend the applicability of our results to show that IP6 also stimulates the acetyltransferase activity of AvrA, the YopJ homologue from Salmonella typhimurium. Furthermore, an IP6-induced conformational change in AvrA suggests that IP6 acts as an allosteric activator of enzyme activity. Our results suggest that YopJ-family enzymes are quiescent in the bacterium where they are synthesized, because bacteria lack IP6; once injected into mammalian cells by the pathogen these toxins bind host cell IP6, are activated, and deregulate the MAPK and NFκB signaling pathways thereby subverting innate immunity.
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Affiliation(s)
- Rohit Mittal
- Medical Research Council (MRC), Laboratory of Molecular Biology, Hills Road, Cambridge CB2 0QH, UK.
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17
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Sialic acids: key determinants for invasion by the Apicomplexa. Int J Parasitol 2010; 40:1145-54. [PMID: 20430033 DOI: 10.1016/j.ijpara.2010.04.007] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2010] [Revised: 04/17/2010] [Accepted: 04/19/2010] [Indexed: 11/20/2022]
Abstract
Sialic acids are ubiquitously found on the surface of all vertebrate cells at the extremities of glycan chains and widely exploited by viruses and bacteria to enter host cells. Carbohydrate-bearing receptors are equally important for host cell invasion by the obligate intracellular protozoan parasites of the phylum Apicomplexa. Host cell entry is an active process relying crucially on proteins that engage with receptors on the host cell surface and promote adhesion and internalisation. Assembly into complexes, proteolytic processing and oligomerization are important requirements for the functionality of these adhesins. The combination of adhesive proteins with varying stringency in specificity confers some flexibility to the parasite in face of receptor heterogeneity and immune pressure. Sialic acids are now recognised to critically contribute to selective host cell recognition by various species of the phylum.
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18
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Friedrich N, Santos JM, Liu Y, Palma AS, Leon E, Saouros S, Kiso M, Blackman MJ, Matthews S, Feizi T, Soldati-Favre D. Members of a novel protein family containing microneme adhesive repeat domains act as sialic acid-binding lectins during host cell invasion by apicomplexan parasites. J Biol Chem 2009; 285:2064-76. [PMID: 19901027 DOI: 10.1074/jbc.m109.060988] [Citation(s) in RCA: 78] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Numerous intracellular pathogens exploit cell surface glycoconjugates for host cell recognition and entry. Unlike bacteria and viruses, Toxoplasma gondii and other parasites of the phylum Apicomplexa actively invade host cells, and this process critically depends on adhesins (microneme proteins) released onto the parasite surface from intracellular organelles called micronemes (MIC). The microneme adhesive repeat (MAR) domain of T. gondii MIC1 (TgMIC1) recognizes sialic acid (Sia), a key determinant on the host cell surface for invasion by this pathogen. By complementation and invasion assays, we demonstrate that TgMIC1 is one important player in Sia-dependent invasion and that another novel Sia-binding lectin, designated TgMIC13, is also involved. Using BLAST searches, we identify a family of MAR-containing proteins in enteroparasitic coccidians, a subclass of apicomplexans, including T. gondii, suggesting that all these parasites exploit sialylated glycoconjugates on host cells as determinants for enteric invasion. Furthermore, this protein family might provide a basis for the broad host cell range observed for coccidians that form tissue cysts during chronic infection. Carbohydrate microarray analyses, corroborated by structural considerations, show that TgMIC13, TgMIC1, and its homologue Neospora caninum MIC1 (NcMIC1) share a preference for alpha2-3- over alpha2-6-linked sialyl-N-acetyllactosamine sequences. However, the three lectins also display differences in binding preferences. Intense binding of TgMIC13 to alpha2-9-linked disialyl sequence reported on embryonal cells and relatively strong binding to 4-O-acetylated-Sia found on gut epithelium and binding of NcMIC1 to 6'sulfo-sialyl Lewis(x) might have implications for tissue tropism.
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Affiliation(s)
- Nikolas Friedrich
- Department of Microbiology and Molecular Medicine, Faculty of Medicine, University of Geneva Centre Medical Universitaire, 1 Rue Michel-Servet, 1211 Geneva 4, Switzerland
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19
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Srinivasan GV, Schauer R. Assays of sialate-O-acetyltransferases and sialate-O-acetylesterases. Glycoconj J 2009; 26:935-44. [PMID: 18566887 DOI: 10.1007/s10719-008-9131-y] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2008] [Revised: 03/20/2008] [Accepted: 03/26/2008] [Indexed: 10/21/2022]
Abstract
The O-acetylation of sialic acids is one of the most frequent modifications of these monosaccharides and modulates many cell biological and pathological events. Sialic acid-specific O-acetyltransferases and O-acetylesterases are responsible for the metabolism of esterified sialic acids. Assays were developed for the analysis of the activities and specificities of these enzymes. The methods had to be varied in dependence on the substrate assayed, the kind of biological source, and the state of enzyme purity. With the new techniques the primary site of O-acetyl incorporation at C-7, catalyzed by the animal sialate-O-acetyltransferases studied, was ascertained. Correspondingly, this enzyme, for example from bovine submandibular gland, can be denominated as AcCoA:sialate-7-O-acetyltransferase (EC 2.3.1.45). Methods for assaying the activity of esterases de-O-acetylating sialic acids and their metabolic cooperation with the O-acetyltransferases are presented.
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Affiliation(s)
- G Vinayaga Srinivasan
- Biochemisches Institut, Christian-Albrechts-Universität, Olshausenstr. 40, 24098 Kiel, Germany
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20
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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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21
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Isolation and properties of two sialate-O-acetylesterases from horse liver with 4- and 9-O-acetyl specificities. Glycoconj J 2008; 25:625-32. [PMID: 18246423 DOI: 10.1007/s10719-008-9109-9] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2007] [Revised: 12/11/2007] [Accepted: 01/14/2008] [Indexed: 10/22/2022]
Abstract
Sialate-O-acetylesterase was purified almost 900-fold from particle-free supernatants of horse liver by gel filtration, ion-exchange chromatography and isoelectric focussing. The native enzyme on gel filtration exhibits a molecular weight of 54,000 Da. It was separated by isoelectric focussing into two forms with pI values of 4.8 and 5.7, respectively. The esterase with a lower pI hydrolyses only 9-O-acetyl groups from sialic acids (K(M) 1.1 mM), while that with the higher pI esterifies both 4- and 9-O-acetylated monosaccharides at similar rates (K(M) 0.3 M and 1.3 mM, respectively). Both forms are inactive with 7-O-acetylated N-acetylneuraminic acid. Enzyme assays were carried out at the pH optimum (pH 8.4-8.6) using free O-acetylated sialic acids followed by direct analysis of the reaction products by isocratic anion-exchange HPLC. Glycosidically bound sialic acids can also be de-O-acetylated. Horse liver esterase seems to be an essential enzyme for the catabolism of 4-O-acetylated sialoglycoconjugates, since sialidase from this tissue cannot act on 4-O-acetylated sialic acids.
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22
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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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23
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Rinninger A, Richet C, Pons A, Kohla G, Schauer R, Bauer HC, Zanetta JP, Vlasak R. Localisation and distribution of O-acetylated N-acetylneuraminic acids, the endogenous substrates of the hemagglutinin-esterases of murine coronaviruses, in mouse tissue. Glycoconj J 2006; 23:73-84. [PMID: 16575524 PMCID: PMC7088067 DOI: 10.1007/s10719-006-5439-7] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Infections by mouse hepatitis viruses result in disease of the liver, the gastrointestinal tract, respiratory tract, and the central nervous system. Coronaviruses related to mouse hepatitis virus express a hemagglutinin-esterase surface glycoprotein, which specifically hydrolyses either 5-N-acetyl-4-O-acetyl neuraminic acid (Neu4,5Ac2) or 5-N-acetyl-9-O-acetyl neuraminic acid (Neu5,9Ac2). Moreover, these sialic acids represent potential cellular receptor determinants for murine coronaviruses. Until now, the distribution of these sialic acids in mouse brain was not thoroughly investigated. Particularly Neu4,5Ac2 was not yet found in mouse brain. Using a sensitive method of gas chromatography coupled to mass spectrometry in the electron impact mode of ionization this manuscript demonstrates the occurrence of 13 different sialic acids varying in their alkyl and acyl substituents in mouse tissues including 5-N-acetyl-4-O-acetyl-9-O-lactyl-neuraminic acid (Neu4,5Ac29Lt), 5-N-acetyl-9-O-lactyl-neuraminic acid (Neu5Ac9Lt), 5-N-acetyl-8-O-methyl-neuraminic acid (Neu5Ac8Me) and the 1,7-lactone (Neu5Ac1,7L) of neuraminic acid. Neu4,5Ac2, relatively abundant in the gut, was present as a minor compound in all tissues, including liver, olfactory lobe, telencephalon, metencephalon and hippocampus. Neu5,9Ac2 was also found in these tissues, except in the liver. It is suggested that these sialic acids represent the endogenous substrate and receptor determinants for murine coronaviruses.
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Affiliation(s)
- Andreas Rinninger
- Applied Biotechnology, Departments of Cell Biology and Organismic Biology, University Salzburg, A-5020 Salzburg, Austria
| | | | - Alexandre Pons
- CNRS Unité Mixte de Recherche 8576, Laboratoire de Glycobiologie Structurale et Fonctionnelle, Université des Sciences et Technologies de Lille, Bâtiment C9, 59655 Villeneuve d'Ascq Cedex, France
| | - Guido Kohla
- Biochemisches Institut, Christian-Albrechts-Universität zu Kiel, Olshausenstr. 40, D-24098 Kiel, Germany
| | - Roland Schauer
- Biochemisches Institut, Christian-Albrechts-Universität zu Kiel, Olshausenstr. 40, D-24098 Kiel, Germany
| | - Hans-Christian Bauer
- Applied Biotechnology, Departments of Cell Biology and Organismic Biology, University Salzburg, A-5020 Salzburg, Austria
| | - Jean-Pierre Zanetta
- CNRS Unité Mixte de Recherche 8576, Laboratoire de Glycobiologie Structurale et Fonctionnelle, Université des Sciences et Technologies de Lille, Bâtiment C9, 59655 Villeneuve d'Ascq Cedex, France
| | - Reinhard Vlasak
- Applied Biotechnology, Departments of Cell Biology and Organismic Biology, University Salzburg, A-5020 Salzburg, Austria
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24
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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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25
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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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26
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Schauer R. Victor Ginsburg's influence on my research of the role of sialic acids in biological recognition. Arch Biochem Biophys 2004; 426:132-41. [PMID: 15158663 DOI: 10.1016/j.abb.2004.03.008] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2004] [Revised: 02/27/2004] [Indexed: 12/11/2022]
Abstract
Sialic acids are monosaccharides with relatively strong acidity which belong to the most important molecules of higher animals and also 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 complex. Sialic acids are involved in a great number of cell functions. Due to their cell surface location these acidic molecules shield macromolecules and cells from enzymatic and immunological attacks and thus contribute to innate immunity. In contrast to this masking role, enabling, for example, blood cells and serum glycoproteins a longer life-time, sialic acids also represent recognition sites for various physiological receptors, such as the selectins and siglecs, as well as for toxins and microorganisms and thus allow their colonization. The recognition function of sialic acids can again be masked by O-acetylation, which modifies the interaction with receptors. Many viruses use sialic acids for the infection of cells. As sialic acids play also a decisive role in tumor biology, they prove to be rather versatile molecules that modulate biological and pathological cellular events in a sensitive way. Thus, they are most prominent representatives of mediators of molecular and cellular recognition.
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Affiliation(s)
- Roland Schauer
- Biochemisches Institut, Christian-Albrechts-Universität, Olshausenstrasse 40, Kiel D-24098, Germany.
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27
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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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