Show legend Show as text

Structure type: polymer chemical repeating unit
Compound class: O-polysaccharide
Contained glycoepitopes: IEDB_133754,IEDB_136105,IEDB_142488,IEDB_144998,IEDB_146664,IEDB_158539,IEDB_225177,IEDB_885823,IEDB_983931,SB_192

• Article ID: 4329
  Knirel YA "Structure of O-antigens" - Book: Bacterial lipopolysaccharides: Structure, chemical synthesis, biogenesis and interaction with host cells (2011) Chapter 3, 41-115
  

  The lipopolysaccharide (LPS) is the major constituent of the outer leaflet of the outer membrane of Gram-negative bacteria. Its lipid A moiety is embedded in the membrane and serves as an anchor for the rest of the LPS molecule. The outermost repetitive glycan region of the LPS is linked to the lipid A through a core oligosaccharide (OS), and is designated as the O-specific polysaccharide (O-polysaccharide, OPS) or O-antigen. The O-antigen is the most variable portion of the LPS and provides serological specificity, which is used for bacterial serotyping. The OPS also provides protection to the microorganisms from host defenses such as complement mediated killing and phagocytosis, and is involved in interactions of bacteria with plants and bacteriophages. Studies of the OPSs ranging from the elucidation of their chemical structures and conformations to their biological and physico-chemical properties help improving classification schemes of Gram-negative bacteria. Furthermore, these studies contributed to a better understanding of the mechanisms of pathogenesis of infectious diseases, as well as provided information to develop novel vaccines and diagnostic reagents.

  Lipopolysaccharide, synthesis, lipopolysaccharides, structure, Bacterial, host, O-antigen, O antigen, cell, O antigens, O-antigens, chemical, interaction, cells, PDF, chemical synthesis, biogenesis

  Publication DOI: 10.1007/978-3-7091-0733-1_3
  Publisher: Springer
  Correspondence: knirel@ioc.ac.ru
  Editors: Knirel YA, Valvano MA
  Institutions: Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, Moscow, Russia
  
   
  
  Xanthomonas campestris pv. pruni
  CSDB ID 27805 (all data & tools)

Show legend Show as text

Structure type: oligomer
Contained glycoepitopes: IEDB_114701,IEDB_115136,IEDB_136044,IEDB_136095,IEDB_136906,IEDB_137472,IEDB_140630,IEDB_141794,IEDB_142487,IEDB_142488,IEDB_144998,IEDB_146664,IEDB_151528,IEDB_167188,IEDB_174332,IEDB_190606,IEDB_423153,IEDB_983931,SB_165,SB_166,SB_187,SB_192,SB_195,SB_6,SB_7,SB_88

• Article ID: 5627
  Dembitsky VM, Rezanka T "Metabolites produced by nitrogen-fixing Nostoc species" - Folia Microbiologica 50(5) (2005) 363-391
  

  This paper provides a comprehensive overview of metabolites, including lipids and lipid-like compounds, boron-containing macrocycles, arsenolipids, oligopeptides and amino acid derivatives, produced by cyanobacteria of the genus Nostoc

  cyanobacteria, lipids, metabolites, Nostoc

  NCBI PubMed ID: 16475497
  Publication DOI: 10.1007/bf02931419
  Journal NLM ID: 0376757
  Publisher: New York: Springer
  Correspondence: rezanka@biomed.cas.cz
  Institutions: Institute of Microbiology, Academy of Sciences of the Czech Republic, Prague, Czech, Department of Organic Chemistry, The Hebrew University of Jerusalem, Jerusalem, Israel
  
   
  
  Nostoc commune HB 261
  CSDB ID 47820 (all data & tools)

Show legend Show as text

Structure type: oligomer
Contained glycoepitopes: IEDB_114701,IEDB_115136,IEDB_136044,IEDB_136095,IEDB_136906,IEDB_137472,IEDB_140630,IEDB_141794,IEDB_142487,IEDB_142488,IEDB_144998,IEDB_146664,IEDB_151528,IEDB_167188,IEDB_174332,IEDB_190606,IEDB_423153,IEDB_983931,SB_165,SB_166,SB_187,SB_192,SB_195,SB_6,SB_7,SB_88

• Article ID: 5627
  Dembitsky VM, Rezanka T "Metabolites produced by nitrogen-fixing Nostoc species" - Folia Microbiologica 50(5) (2005) 363-391
  

  This paper provides a comprehensive overview of metabolites, including lipids and lipid-like compounds, boron-containing macrocycles, arsenolipids, oligopeptides and amino acid derivatives, produced by cyanobacteria of the genus Nostoc

  cyanobacteria, lipids, metabolites, Nostoc

  NCBI PubMed ID: 16475497
  Publication DOI: 10.1007/bf02931419
  Journal NLM ID: 0376757
  Publisher: New York: Springer
  Correspondence: rezanka@biomed.cas.cz
  Institutions: Institute of Microbiology, Academy of Sciences of the Czech Republic, Prague, Czech, Department of Organic Chemistry, The Hebrew University of Jerusalem, Jerusalem, Israel
  
   
  
  Nostoc commune HB 261
  CSDB ID 47821 (all data & tools)

Show legend Show as text

Structure type: structural motif or average structure
Compound class: glucuronoxylomannan
Contained glycoepitopes: IEDB_114701,IEDB_115136,IEDB_115576,IEDB_130701,IEDB_1394182,IEDB_140116,IEDB_140630,IEDB_144983,IEDB_145668,IEDB_152206,IEDB_164174,IEDB_167188,IEDB_174332,IEDB_2270799,IEDB_423153,IEDB_76933,IEDB_983930,SB_197,SB_44,SB_67,SB_72

• Article ID: 6926
  Doering TL "A unique alpha-1,3 mannosyltransferase of the pathogenic fungus Cryptococcus neoformans" - Journal of Bacteriology 181 (1999) 5482-5488
  

  The major virulence factor of the pathogenic fungusCryptococcus neoformans is an extensive polysaccharide capsule which surrounds the cell. Almost 90% of the capsule is composed of a partially acetylated linear α-1,3-linked mannan substituted with D-xylose and D-glucuronic acid. A novel mannosyltransferase with specificity appropriate for a role in the synthesis of this glucuronoxylomannan is active in cryptococcal membranes. This membrane-associated activity transfers mannose in vitro from GDP-mannose to an α-1,3-dimannoside acceptor, forming a second α-1,3 linkage. Product formation by the transferase is dependent on protein, time, temperature, divalent cations, and each substrate. It is not affected by amphomycin or tunicamycin but is inhibited by GDP and mannose-1-phosphate. The described activity is not detectable in the model yeast Saccharomyces cerevisiae, consistent with the absence of a similar polysaccharide structure in that organism. A second mannosyltransferase from C. neoformans membranes adds mannose in α-1,2 linkage to the same dimannoside acceptor. The two activities differ in pH optimum and cation preference. While the α-1,2 transferase does not have specificity appropriate for a role in glucuronoxylomannan synthesis, it may participate in production of mannoprotein components of the capsule. This study suggests two new targets for antifungal drug discovery.

  Journal NLM ID: 2985120R
  WWW link: http://jb.asm.org/content/181/17/5482.long
  Publisher: American Society for Microbiology
  Correspondence: doering@borcim.wustl.edu
  Institutions: Department of Pharmacology, Cornell University Medical College, New York, New York
  Methods: enzymatic digestion, enzymatic assay, radiolabelling
  
   
  
  Cryptococcus neoformans B
  CSDB ID 40487 (all data & tools)

Show legend Show as text

Structure type: suggested polymer biological repeating unit
Contained glycoepitopes: IEDB_114701,IEDB_115136,IEDB_115576,IEDB_130701,IEDB_1394182,IEDB_140116,IEDB_140630,IEDB_144983,IEDB_145668,IEDB_152206,IEDB_164174,IEDB_167188,IEDB_174332,IEDB_2270799,IEDB_423153,IEDB_76933,IEDB_983930,SB_197,SB_44,SB_67,SB_72

• Article ID: 6961
  Bar-Peled M, Griffith CL, Doering TL "Functional cloning and characterization of a UDP-glucuronic acid decarboxylase: the pathogenic fungus Cryptococcus neoformans elucidates UDP-xylose synthesis" - Proceedings of the National Academy of Sciences of the USA 21 (2001) 12003-12008
  

  UDP-xylose is a sugar donor required for the synthesis of diverse and important glycan structures in animals, plants, fungi, and bacteria. Xylose-containing glycans are particularly abundant in plants and in the polysaccharide capsule that is the major virulence factor of the pathogenic fungus Cryptococcus neoformans. Biosynthesis of UDP-xylose is mediated by UDP-glucuronic acid decarboxylase, which converts UDP-glucuronic acid to UDP-xylose. Although this enzymatic activity was described over 40 years ago it has never been fully purified, and the gene encoding it has not been identified. We used homology to a bacterial gene, hypothesized to encode a related function, to identify a cryptococcal sequence as putatively encoding a UDP-glucuronic acid decarboxylase. A soluble 47-kDa protein derived from bacteria expressing the C. neoformans gene catalyzed conversion of UDP-glucuronic acid to UDP-xylose, as confirmed by NMR analysis. NADH, UDP, and UDP-xylose inhibit the activity. Close homologs of the cryptococcal gene, which we termed UXS1, appear in genome sequence data from organisms ranging from bacteria to humans.

  Publication DOI: 10.1073/pnas.211229198
  Journal NLM ID: 7505876
  Publisher: National Academy of Sciences
  Correspondence: peled@ccrc.uga.edu
  Institutions: Complex Carbohydrate Research Center and Department of Botany, University of Georgia, Athens, GA 30602, USA, Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, MO 63110, USA
  Methods: 1H NMR, SDS-PAGE, HPLC, cloning, protein expression, UDP-GlcA decarboxylase assay
  
   
  
  Cryptococcus neoformans B
  CSDB ID 40538 (all data & tools)

Show legend Show as text

Structure type: polymer chemical repeating unit
Contained glycoepitopes: IEDB_114701,IEDB_130701,IEDB_134624,IEDB_136044,IEDB_136095,IEDB_136906,IEDB_137472,IEDB_1394182,IEDB_141794,IEDB_144983,IEDB_145668,IEDB_151528,IEDB_152206,IEDB_164174,IEDB_167188,IEDB_174332,IEDB_190606,IEDB_983930,SB_163,SB_165,SB_166,SB_187,SB_195,SB_197,SB_44,SB_67,SB_7,SB_72,SB_88

• Article ID: 6961
  Bar-Peled M, Griffith CL, Doering TL "Functional cloning and characterization of a UDP-glucuronic acid decarboxylase: the pathogenic fungus Cryptococcus neoformans elucidates UDP-xylose synthesis" - Proceedings of the National Academy of Sciences of the USA 21 (2001) 12003-12008
  

  UDP-xylose is a sugar donor required for the synthesis of diverse and important glycan structures in animals, plants, fungi, and bacteria. Xylose-containing glycans are particularly abundant in plants and in the polysaccharide capsule that is the major virulence factor of the pathogenic fungus Cryptococcus neoformans. Biosynthesis of UDP-xylose is mediated by UDP-glucuronic acid decarboxylase, which converts UDP-glucuronic acid to UDP-xylose. Although this enzymatic activity was described over 40 years ago it has never been fully purified, and the gene encoding it has not been identified. We used homology to a bacterial gene, hypothesized to encode a related function, to identify a cryptococcal sequence as putatively encoding a UDP-glucuronic acid decarboxylase. A soluble 47-kDa protein derived from bacteria expressing the C. neoformans gene catalyzed conversion of UDP-glucuronic acid to UDP-xylose, as confirmed by NMR analysis. NADH, UDP, and UDP-xylose inhibit the activity. Close homologs of the cryptococcal gene, which we termed UXS1, appear in genome sequence data from organisms ranging from bacteria to humans.

  Publication DOI: 10.1073/pnas.211229198
  Journal NLM ID: 7505876
  Publisher: National Academy of Sciences
  Correspondence: peled@ccrc.uga.edu
  Institutions: Complex Carbohydrate Research Center and Department of Botany, University of Georgia, Athens, GA 30602, USA, Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, MO 63110, USA
  Methods: 1H NMR, SDS-PAGE, HPLC, cloning, protein expression, UDP-GlcA decarboxylase assay
  
   
  
  Cryptococcus neoformans
  CSDB ID 40794 (all data & tools)

Show legend Show as text

Structure type: polymer chemical repeating unit
Compound class: CPS, glucuronoxylomannan (GXM)
Contained glycoepitopes: IEDB_114701,IEDB_115136,IEDB_115576,IEDB_130701,IEDB_1394182,IEDB_140116,IEDB_140630,IEDB_144983,IEDB_145668,IEDB_152206,IEDB_164174,IEDB_167188,IEDB_174332,IEDB_423153,IEDB_76933,IEDB_983930,SB_197,SB_44,SB_67,SB_72

• Article ID: 7125
  McFadden DC, Fries BC, Wang F, Casadevall A "Capsule structural heterogeneity and antigenic variation in Cryptococcus neoformans" - Eukaryotic Cell 6(8) (2007) 1464-1473
  

  Cryptococcus neoformans is a human pathogenic fungus with a capsule composed primarily of glucuronoxylomannan (GXM) that is important for virulence. Current views of GXM structure postulate a polymer composed of repeating mannose trisaccharide motifs bearing a single β(1,2) glucuronic acid with variable xylose and O-acetyl substitutions to form six triads. GXM from different strains is notoriously variable in triad composition, but it is not known if the polymer consists of one or more motif-repeating units. We investigated the polymeric organization of GXM by using mass spectrometry to determine if its compositional motif arrangement was similar to that of bacterial capsular polysaccharides, namely, a polymer of a single repeating unit. The results were consistent with, and confirmatory for, the current view that the basic unit of GXM is a repeating mannose trisaccharide motif, but we also found evidence for the copolymerization of different GXM repeating units in one polysaccharide molecule. Analysis of GXM from isogenic phenotypic switch variants suggested structural differences caused by glucuronic acid positional effects, which implied flexibility in the synthetic pathway. Our results suggest that cryptococcal capsule synthesis is fundamentally different from that observed in prokaryotes and employs a unique eukaryotic approach, which theoretically could synthesize an infinite number of structural combinations. The biological significance of this capsule construction scheme is that it is likely to confer a powerful avoidance strategy for interactions with the immune system and phagocytic environmental predators. Consistent with this premise, the antigenic variation of a capsular epitope recognized by a nonprotective antibody was observed under different growth conditions.

  biosynthesis, antibodies, infection, polysaccharide capsule, Glucuronoxylomannan

  Publication DOI: 10.1128/EC.00162-07
  Journal NLM ID: 101130731
  Publisher: American Society for Microbiology
  Correspondence: Arturo Casadevall
  Institutions: Department of Medicine, Division of Infectious Disease, Department of Microbiology and Immunology, Laboratory for Macromolecular Analysis and Proteomics, Albert Einstein College of Medicine, Bronx, New York 10461
  Methods: 1H NMR, partial acid hydrolysis, TLC, ESI-MS, acid hydrolysis, MS/MS, electrophoresis, HPLC, light scattering, viscosity measurement
  
   
  
  Cryptococcus neoformans D
  CSDB ID 41797 (all data & tools)

Show legend Show as text

Structure type: polymer chemical repeating unit
Compound class: CPS, EPS, glucuronoxylomannan (GXM)
Contained glycoepitopes: IEDB_114701,IEDB_115136,IEDB_115576,IEDB_130701,IEDB_1394182,IEDB_140116,IEDB_140630,IEDB_144983,IEDB_145668,IEDB_152206,IEDB_164174,IEDB_167188,IEDB_174332,IEDB_2270799,IEDB_423153,IEDB_76933,IEDB_983930,SB_197,SB_44,SB_67,SB_72

• Article ID: 7125
  McFadden DC, Fries BC, Wang F, Casadevall A "Capsule structural heterogeneity and antigenic variation in Cryptococcus neoformans" - Eukaryotic Cell 6(8) (2007) 1464-1473
  

  Cryptococcus neoformans is a human pathogenic fungus with a capsule composed primarily of glucuronoxylomannan (GXM) that is important for virulence. Current views of GXM structure postulate a polymer composed of repeating mannose trisaccharide motifs bearing a single β(1,2) glucuronic acid with variable xylose and O-acetyl substitutions to form six triads. GXM from different strains is notoriously variable in triad composition, but it is not known if the polymer consists of one or more motif-repeating units. We investigated the polymeric organization of GXM by using mass spectrometry to determine if its compositional motif arrangement was similar to that of bacterial capsular polysaccharides, namely, a polymer of a single repeating unit. The results were consistent with, and confirmatory for, the current view that the basic unit of GXM is a repeating mannose trisaccharide motif, but we also found evidence for the copolymerization of different GXM repeating units in one polysaccharide molecule. Analysis of GXM from isogenic phenotypic switch variants suggested structural differences caused by glucuronic acid positional effects, which implied flexibility in the synthetic pathway. Our results suggest that cryptococcal capsule synthesis is fundamentally different from that observed in prokaryotes and employs a unique eukaryotic approach, which theoretically could synthesize an infinite number of structural combinations. The biological significance of this capsule construction scheme is that it is likely to confer a powerful avoidance strategy for interactions with the immune system and phagocytic environmental predators. Consistent with this premise, the antigenic variation of a capsular epitope recognized by a nonprotective antibody was observed under different growth conditions.

  biosynthesis, antibodies, infection, polysaccharide capsule, Glucuronoxylomannan

  Publication DOI: 10.1128/EC.00162-07
  Journal NLM ID: 101130731
  Publisher: American Society for Microbiology
  Correspondence: Arturo Casadevall
  Institutions: Department of Medicine, Division of Infectious Disease, Department of Microbiology and Immunology, Laboratory for Macromolecular Analysis and Proteomics, Albert Einstein College of Medicine, Bronx, New York 10461
  Methods: 1H NMR, partial acid hydrolysis, TLC, ESI-MS, acid hydrolysis, MS/MS, electrophoresis, HPLC, light scattering, viscosity measurement
  
   
  
  Cryptococcus neoformans A
  CSDB ID 42199 (all data & tools)
• Article ID: 7136
  Liu OW, Kelly MJ, Chow ED, Madhani HD "Parallel beta-helix proteins required for accurate capsule polysaccharide synthesis and virulence in the yeast Cryptococcus neoformans" - Eukaryotic Cell 6(4) (2007) 630-640
  

  The principal capsular polysaccharide of the opportunistic fungal pathogen Cryptococcus neoformans consists of an α-1,3-linked mannose backbone decorated with a repeating pattern of glucuronyl and xylosyl side groups. This structure is critical for virulence, yet little is known about how the polymer, called glucuronoxylomannan (GXM), is faithfully synthesized and assembled. We have generated deletions in two genes encoding predicted parallel β-helix repeat proteins, which we have designated PBX1 and PBX2. Deletion of either gene results in a dry-colony morphology, clumpy cells, and decreased capsule integrity. Two-dimensional nuclear magnetic resonance spectroscopy of purified GXM from the mutants indicated that both the wild-type GXM structure and novel, aberrant linkages were present. Carbohydrate composition and linkage analysis determined that these aberrant structures are correlated with the incorporation of terminal glucose residues that are not found in wild-type capsule polysaccharide. We conclude that Pbx1 and Pbx2 are required for the fidelity of GXM synthesis and may be involved in editing incorrectly added glucose residues. PBX1 and PBX2 knockout mutants showed severely attenuated virulence in a murine inhalation model of cryptococcosis. Unlike acapsular strains, these mutant strains induced delayed symptoms of cryptococcosis, though the infected animals eventually contained the infection and recovered.

  gene, UDP-Glucose dehydrogenase, Cryptococcus neoformans, glucuronoxylomannan (GXM)

  NCBI PubMed ID: 17337638
  Publication DOI: 10.1128/EC.00398-06
  Journal NLM ID: 101130731
  Publisher: American Society for Microbiology
  Correspondence: Madhani HD
  Institutions: Department of Biochemistry and Biophysics and Department of Pharmaceutical Chemistry, University of California, San Francisco, California, USA
  Methods: 13C NMR, 1H NMR, NMR-2D, virulence assays, PCR, GLC-EI-MS, acid hydrolysis, composition analysis, genetic methods, HPAEC-PAD, microscopy
  
   
  
  Cryptococcus neoformans A H99
  CSDB ID 41809 (all data & tools)

Show legend Show as text

Structure type: suggested polymer biological repeating unit
Compound class: CPS, glucuronoxylomannan (GXM)
Contained glycoepitopes: IEDB_114701,IEDB_115136,IEDB_115576,IEDB_130701,IEDB_1394182,IEDB_140116,IEDB_140630,IEDB_144983,IEDB_145668,IEDB_152206,IEDB_164174,IEDB_167188,IEDB_174332,IEDB_2270799,IEDB_423153,IEDB_76933,IEDB_983930,SB_197,SB_44,SB_67,SB_72

• Article ID: 7125
  McFadden DC, Fries BC, Wang F, Casadevall A "Capsule structural heterogeneity and antigenic variation in Cryptococcus neoformans" - Eukaryotic Cell 6(8) (2007) 1464-1473
  

  Cryptococcus neoformans is a human pathogenic fungus with a capsule composed primarily of glucuronoxylomannan (GXM) that is important for virulence. Current views of GXM structure postulate a polymer composed of repeating mannose trisaccharide motifs bearing a single β(1,2) glucuronic acid with variable xylose and O-acetyl substitutions to form six triads. GXM from different strains is notoriously variable in triad composition, but it is not known if the polymer consists of one or more motif-repeating units. We investigated the polymeric organization of GXM by using mass spectrometry to determine if its compositional motif arrangement was similar to that of bacterial capsular polysaccharides, namely, a polymer of a single repeating unit. The results were consistent with, and confirmatory for, the current view that the basic unit of GXM is a repeating mannose trisaccharide motif, but we also found evidence for the copolymerization of different GXM repeating units in one polysaccharide molecule. Analysis of GXM from isogenic phenotypic switch variants suggested structural differences caused by glucuronic acid positional effects, which implied flexibility in the synthetic pathway. Our results suggest that cryptococcal capsule synthesis is fundamentally different from that observed in prokaryotes and employs a unique eukaryotic approach, which theoretically could synthesize an infinite number of structural combinations. The biological significance of this capsule construction scheme is that it is likely to confer a powerful avoidance strategy for interactions with the immune system and phagocytic environmental predators. Consistent with this premise, the antigenic variation of a capsular epitope recognized by a nonprotective antibody was observed under different growth conditions.

  biosynthesis, antibodies, infection, polysaccharide capsule, Glucuronoxylomannan

  Publication DOI: 10.1128/EC.00162-07
  Journal NLM ID: 101130731
  Publisher: American Society for Microbiology
  Correspondence: Arturo Casadevall
  Institutions: Department of Medicine, Division of Infectious Disease, Department of Microbiology and Immunology, Laboratory for Macromolecular Analysis and Proteomics, Albert Einstein College of Medicine, Bronx, New York 10461
  Methods: 1H NMR, partial acid hydrolysis, TLC, ESI-MS, acid hydrolysis, MS/MS, electrophoresis, HPLC, light scattering, viscosity measurement
  
   
  
  Cryptococcus neoformans B
  CSDB ID 42200 (all data & tools)

Show legend Show as text

Structure type: suggested polymer biological repeating unit
Compound class: CPS, glucuronoxylomannan (GXM)
Contained glycoepitopes: IEDB_114701,IEDB_115136,IEDB_115576,IEDB_130701,IEDB_1394182,IEDB_140116,IEDB_140630,IEDB_144983,IEDB_145668,IEDB_152206,IEDB_164174,IEDB_167188,IEDB_174332,IEDB_2270799,IEDB_423153,IEDB_76933,IEDB_983930,SB_197,SB_44,SB_67,SB_72

• Article ID: 7125
  McFadden DC, Fries BC, Wang F, Casadevall A "Capsule structural heterogeneity and antigenic variation in Cryptococcus neoformans" - Eukaryotic Cell 6(8) (2007) 1464-1473
  

  Cryptococcus neoformans is a human pathogenic fungus with a capsule composed primarily of glucuronoxylomannan (GXM) that is important for virulence. Current views of GXM structure postulate a polymer composed of repeating mannose trisaccharide motifs bearing a single β(1,2) glucuronic acid with variable xylose and O-acetyl substitutions to form six triads. GXM from different strains is notoriously variable in triad composition, but it is not known if the polymer consists of one or more motif-repeating units. We investigated the polymeric organization of GXM by using mass spectrometry to determine if its compositional motif arrangement was similar to that of bacterial capsular polysaccharides, namely, a polymer of a single repeating unit. The results were consistent with, and confirmatory for, the current view that the basic unit of GXM is a repeating mannose trisaccharide motif, but we also found evidence for the copolymerization of different GXM repeating units in one polysaccharide molecule. Analysis of GXM from isogenic phenotypic switch variants suggested structural differences caused by glucuronic acid positional effects, which implied flexibility in the synthetic pathway. Our results suggest that cryptococcal capsule synthesis is fundamentally different from that observed in prokaryotes and employs a unique eukaryotic approach, which theoretically could synthesize an infinite number of structural combinations. The biological significance of this capsule construction scheme is that it is likely to confer a powerful avoidance strategy for interactions with the immune system and phagocytic environmental predators. Consistent with this premise, the antigenic variation of a capsular epitope recognized by a nonprotective antibody was observed under different growth conditions.

  biosynthesis, antibodies, infection, polysaccharide capsule, Glucuronoxylomannan

  Publication DOI: 10.1128/EC.00162-07
  Journal NLM ID: 101130731
  Publisher: American Society for Microbiology
  Correspondence: Arturo Casadevall
  Institutions: Department of Medicine, Division of Infectious Disease, Department of Microbiology and Immunology, Laboratory for Macromolecular Analysis and Proteomics, Albert Einstein College of Medicine, Bronx, New York 10461
  Methods: 1H NMR, partial acid hydrolysis, TLC, ESI-MS, acid hydrolysis, MS/MS, electrophoresis, HPLC, light scattering, viscosity measurement
  
   
  
  Cryptococcus neoformans C
  CSDB ID 42201 (all data & tools)

Show legend Show as text

Structure type: suggested polymer biological repeating unit
Compound class: CPS, glucuronoxylomannan (GXM)
Contained glycoepitopes: IEDB_114701,IEDB_115136,IEDB_115576,IEDB_130701,IEDB_1394182,IEDB_140116,IEDB_140630,IEDB_144983,IEDB_145668,IEDB_152206,IEDB_164174,IEDB_167188,IEDB_174332,IEDB_423153,IEDB_76933,IEDB_983930,SB_197,SB_44,SB_67,SB_72

• Article ID: 7125
  McFadden DC, Fries BC, Wang F, Casadevall A "Capsule structural heterogeneity and antigenic variation in Cryptococcus neoformans" - Eukaryotic Cell 6(8) (2007) 1464-1473
  

  Cryptococcus neoformans is a human pathogenic fungus with a capsule composed primarily of glucuronoxylomannan (GXM) that is important for virulence. Current views of GXM structure postulate a polymer composed of repeating mannose trisaccharide motifs bearing a single β(1,2) glucuronic acid with variable xylose and O-acetyl substitutions to form six triads. GXM from different strains is notoriously variable in triad composition, but it is not known if the polymer consists of one or more motif-repeating units. We investigated the polymeric organization of GXM by using mass spectrometry to determine if its compositional motif arrangement was similar to that of bacterial capsular polysaccharides, namely, a polymer of a single repeating unit. The results were consistent with, and confirmatory for, the current view that the basic unit of GXM is a repeating mannose trisaccharide motif, but we also found evidence for the copolymerization of different GXM repeating units in one polysaccharide molecule. Analysis of GXM from isogenic phenotypic switch variants suggested structural differences caused by glucuronic acid positional effects, which implied flexibility in the synthetic pathway. Our results suggest that cryptococcal capsule synthesis is fundamentally different from that observed in prokaryotes and employs a unique eukaryotic approach, which theoretically could synthesize an infinite number of structural combinations. The biological significance of this capsule construction scheme is that it is likely to confer a powerful avoidance strategy for interactions with the immune system and phagocytic environmental predators. Consistent with this premise, the antigenic variation of a capsular epitope recognized by a nonprotective antibody was observed under different growth conditions.

  biosynthesis, antibodies, infection, polysaccharide capsule, Glucuronoxylomannan

  Publication DOI: 10.1128/EC.00162-07
  Journal NLM ID: 101130731
  Publisher: American Society for Microbiology
  Correspondence: Arturo Casadevall
  Institutions: Department of Medicine, Division of Infectious Disease, Department of Microbiology and Immunology, Laboratory for Macromolecular Analysis and Proteomics, Albert Einstein College of Medicine, Bronx, New York 10461
  Methods: 1H NMR, partial acid hydrolysis, TLC, ESI-MS, acid hydrolysis, MS/MS, electrophoresis, HPLC, light scattering, viscosity measurement
  
   
  
  Cryptococcus neoformans
  CSDB ID 42202 (all data & tools)

Show legend Show as text

Structure type: oligomer
Compound class: glycosphingolipid, glycoinositolphosphoryl ceramide (GIPC)
Contained glycoepitopes: IEDB_114701,IEDB_130701,IEDB_136044,IEDB_137472,IEDB_1394182,IEDB_140116,IEDB_141793,IEDB_141794,IEDB_144983,IEDB_145668,IEDB_152206,IEDB_153220,IEDB_164174,IEDB_167188,IEDB_174332,IEDB_190606,IEDB_983930,SB_165,SB_166,SB_187,SB_195,SB_197,SB_198,SB_44,SB_67,SB_7,SB_72,SB_88

• Article ID: 7132
  Gutierrez AL, Farage L, Melo MN, Mohana-Borges RS, Guerardel Y, Coddeville B, Wieruszeski JM, Mendonça-Previato L, Previato JO "Characterization of glycoinositolphosphoryl ceramide structure mutant strains of Cryptococcus neoformans" - Glycobiology 17(6) (2007) 1C-11C
  

  In fungi, glycoinositolphosphoryl ceramide (GIPC) biosynthetic pathway produces essential molecules for growth, viability, and virulence. In previous studies, we demonstrated that the opportunistic fungus Cryptococcus neoformans synthesizes a complex family of xylose-(Xyl) branched GIPCs, all of which have not been previously reported in fungi. As an effort to understand the biosynthesis of these sphingolipids, we have now characterized the structures of GIPCs from C. neoformans wild-type (KN99α) and mutant strains that lack UDP-Xyl, by disruption of either UDP-glucose dehydrogenase (NE321) or UDP-glucuronic acid decarboxylase (NE178). The structures of GIPCs were determined by a combination of nuclear magnetic resonance (NMR) spectroscopy, tandem mass spectrometry (MS), and gas chromatography-MS. The main and largest GIPC from wild-type strain was identified as an α-Manp(1→6)α-Manp(1→3)α-Manp[β-Xylp(1→2)]α-Manp(1→4)β-Galp(1→6)α-Manp(1→2)Ins-1-P-Ceramide, whereas the most abundant GIPC from both mutant strains was found to be an α-Manp(1→3)α-Manp(1→4)β-Galp(1→6)α-Manp(1→2)Ins-1-P-Ceramide. The ceramide moieties of C. neoformans wild-type and mutant strains were composed of a C(18) phytosphingosine, which was N-acylated with 2-hydroxy tetra-, or hexacosanoic acid, and 2,3-dihydroxy-tetracosanoic acid. Our structural analysis results indicate that the C. neoformans mutant strains are unable to complete the assembly of the GIPC-oligosaccharide moiety due the absence of Xyl side chain.

  NMR spectroscopy, mass spectrometry, Cryptococcus neoformans, Cryptococcus mutants, glycoinositolphosphoryl ceramide, UDP-Xyl

  NCBI PubMed ID: 17369287
  Publication DOI: 10.1093/glycob/cwm030
  Journal NLM ID: 9104124
  Publisher: IRL Press at Oxford University Press
  Correspondence: luciamp@biof.ufrj.br
  Institutions: Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Cidade Universitária, Rio de Janeiro, Brasil, Unité de Glycobiologie, Structurale et Fonctionnelle, Université des Sciences et Technologies de Lille, Villeneuve D'Ascq, France
  Methods: 13C NMR, 1H NMR, GC-MS, ESI-MS/MS, GC, composition analysis, methanolysis, GPC, alkaline hydrolysis, extraction, permethylation, CID-MS, HPTLC, nESI-QTOF-MS, MALDI-TOF-MS
  
   
  
  Cryptococcus neoformans KN99a
  CSDB ID 41805 (all data & tools)

Show legend Show as text

Structure type: oligomer
Compound class: glycosphingolipid, glycoinositolphosphoryl ceramide (GIPC)
Contained glycoepitopes: IEDB_114701,IEDB_130701,IEDB_136044,IEDB_137472,IEDB_1394182,IEDB_141794,IEDB_144983,IEDB_145668,IEDB_152206,IEDB_164174,IEDB_167188,IEDB_174332,IEDB_190606,IEDB_983930,SB_165,SB_166,SB_187,SB_195,SB_197,SB_44,SB_67,SB_7,SB_72,SB_88

• Article ID: 7132
  Gutierrez AL, Farage L, Melo MN, Mohana-Borges RS, Guerardel Y, Coddeville B, Wieruszeski JM, Mendonça-Previato L, Previato JO "Characterization of glycoinositolphosphoryl ceramide structure mutant strains of Cryptococcus neoformans" - Glycobiology 17(6) (2007) 1C-11C
  

  In fungi, glycoinositolphosphoryl ceramide (GIPC) biosynthetic pathway produces essential molecules for growth, viability, and virulence. In previous studies, we demonstrated that the opportunistic fungus Cryptococcus neoformans synthesizes a complex family of xylose-(Xyl) branched GIPCs, all of which have not been previously reported in fungi. As an effort to understand the biosynthesis of these sphingolipids, we have now characterized the structures of GIPCs from C. neoformans wild-type (KN99α) and mutant strains that lack UDP-Xyl, by disruption of either UDP-glucose dehydrogenase (NE321) or UDP-glucuronic acid decarboxylase (NE178). The structures of GIPCs were determined by a combination of nuclear magnetic resonance (NMR) spectroscopy, tandem mass spectrometry (MS), and gas chromatography-MS. The main and largest GIPC from wild-type strain was identified as an α-Manp(1→6)α-Manp(1→3)α-Manp[β-Xylp(1→2)]α-Manp(1→4)β-Galp(1→6)α-Manp(1→2)Ins-1-P-Ceramide, whereas the most abundant GIPC from both mutant strains was found to be an α-Manp(1→3)α-Manp(1→4)β-Galp(1→6)α-Manp(1→2)Ins-1-P-Ceramide. The ceramide moieties of C. neoformans wild-type and mutant strains were composed of a C(18) phytosphingosine, which was N-acylated with 2-hydroxy tetra-, or hexacosanoic acid, and 2,3-dihydroxy-tetracosanoic acid. Our structural analysis results indicate that the C. neoformans mutant strains are unable to complete the assembly of the GIPC-oligosaccharide moiety due the absence of Xyl side chain.

  NMR spectroscopy, mass spectrometry, Cryptococcus neoformans, Cryptococcus mutants, glycoinositolphosphoryl ceramide, UDP-Xyl

  NCBI PubMed ID: 17369287
  Publication DOI: 10.1093/glycob/cwm030
  Journal NLM ID: 9104124
  Publisher: IRL Press at Oxford University Press
  Correspondence: luciamp@biof.ufrj.br
  Institutions: Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Cidade Universitária, Rio de Janeiro, Brasil, Unité de Glycobiologie, Structurale et Fonctionnelle, Université des Sciences et Technologies de Lille, Villeneuve D'Ascq, France
  Methods: 13C NMR, 1H NMR, GC-MS, ESI-MS/MS, GC, composition analysis, methanolysis, GPC, alkaline hydrolysis, extraction, permethylation, CID-MS, HPTLC, nESI-QTOF-MS, MALDI-TOF-MS
  
   
  
  Cryptococcus neoformans 444
  CSDB ID 42035 (all data & tools)

Show legend Show as text

Structure type: oligomer
Aglycon: (->3) Ser/Thr-protein
Compound class: EPS, O-glycan
Contained glycoepitopes: IEDB_114701,IEDB_130701,IEDB_136104,IEDB_1394182,IEDB_140116,IEDB_141793,IEDB_141829,IEDB_143632,IEDB_144983,IEDB_145668,IEDB_152206,IEDB_153220,IEDB_164174,IEDB_167188,IEDB_174332,IEDB_76933,IEDB_983930,SB_136,SB_191,SB_196,SB_197,SB_198,SB_44,SB_67,SB_72

• Article ID: 7134
  Schutzbach J, Ankel H, Brockhausen I "Synthesis of cell envelope glycoproteins of Cryptococcus laurentii" - Carbohydrate Research 342(7) (2007) 881-893
  

  Fungi of the genus Cryptococcus are encapsulated basidiomycetes that are ubiquitously found in the environment. These organisms infect both lower and higher animals. Human infections that are common in immune-compromised individuals have proven difficult to cure or even control with currently available antimycotics that are quite often toxic to the host. The virulence of Cryptococcus has been linked primarily to its polysaccharide capsule, but also to cell-bound glycoproteins. In this review, we show that Cryptococcus laurentii is an excellent model for studies of polysaccharide and glycoprotein synthesis in the more pathogenic relative C. neoformans. In particular, we will discuss the structure and biosynthesis of O-linked carbohydrates on cell envelope glycoproteins of C. laurentii. These O-linked structures are synthesized by at least four mannosyltransferases, two galactosyltransferases, and at least one xylosyltransferase that have been characterized. These glycosyltransferases have no known homologues in human tissues. Therefore, enzymes involved in the synthesis of cryptococcal glycoproteins, as well as related enzymes involved in capsule synthesis, are potential targets for the development of specific inhibitors for treatment of cryptococcal disease.

  synthesis, galactosyltransferase, sugar nucleotides, Mannosyltransferase, Cryptococcus neoformans, Cryptococcus laurentii, O-Linked glycoprotein synthesis, Xylosyltransferase, AIDS

  NCBI PubMed ID: 17316583
  Publication DOI: 10.1016/j.carres.2007.01.002
  Journal NLM ID: 0043535
  Publisher: Elsevier
  Correspondence: Inka.JSBach@kos.net (John Schutzbach)
  Institutions: Department of Medicine and Department of Biochemistry, Queen’s University, Etherington Hall, Kingston, Ontario, Canada, Service de Virologie, Hôpital Saint-Vincent-de-Paul, Faculté de Médecine, Université René Descartes, Paris, France
  
   
  
  Cryptococcus laurentii
  CSDB ID 42039 (all data & tools)

Show legend Show as text

Structure type: structural motif or average structure
Compound class: CPS, glucuronoxylomannan (GXM)
Contained glycoepitopes: IEDB_114701,IEDB_115136,IEDB_115576,IEDB_130701,IEDB_137485,IEDB_1394182,IEDB_140116,IEDB_140630,IEDB_144983,IEDB_152206,IEDB_164174,IEDB_167188,IEDB_174332,IEDB_423153,IEDB_76933,IEDB_983930,SB_197,SB_44,SB_67,SB_72

• Article ID: 7134
  Schutzbach J, Ankel H, Brockhausen I "Synthesis of cell envelope glycoproteins of Cryptococcus laurentii" - Carbohydrate Research 342(7) (2007) 881-893
  

  Fungi of the genus Cryptococcus are encapsulated basidiomycetes that are ubiquitously found in the environment. These organisms infect both lower and higher animals. Human infections that are common in immune-compromised individuals have proven difficult to cure or even control with currently available antimycotics that are quite often toxic to the host. The virulence of Cryptococcus has been linked primarily to its polysaccharide capsule, but also to cell-bound glycoproteins. In this review, we show that Cryptococcus laurentii is an excellent model for studies of polysaccharide and glycoprotein synthesis in the more pathogenic relative C. neoformans. In particular, we will discuss the structure and biosynthesis of O-linked carbohydrates on cell envelope glycoproteins of C. laurentii. These O-linked structures are synthesized by at least four mannosyltransferases, two galactosyltransferases, and at least one xylosyltransferase that have been characterized. These glycosyltransferases have no known homologues in human tissues. Therefore, enzymes involved in the synthesis of cryptococcal glycoproteins, as well as related enzymes involved in capsule synthesis, are potential targets for the development of specific inhibitors for treatment of cryptococcal disease.

  synthesis, galactosyltransferase, sugar nucleotides, Mannosyltransferase, Cryptococcus neoformans, Cryptococcus laurentii, O-Linked glycoprotein synthesis, Xylosyltransferase, AIDS

  NCBI PubMed ID: 17316583
  Publication DOI: 10.1016/j.carres.2007.01.002
  Journal NLM ID: 0043535
  Publisher: Elsevier
  Correspondence: Inka.JSBach@kos.net (John Schutzbach)
  Institutions: Department of Medicine and Department of Biochemistry, Queen’s University, Etherington Hall, Kingston, Ontario, Canada, Service de Virologie, Hôpital Saint-Vincent-de-Paul, Faculté de Médecine, Université René Descartes, Paris, France
  
   
  
  Cryptococcus flavescens
  CSDB ID 42041 (all data & tools)