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Structure type: cyclic polymer repeating unit ; n=17-25
Trivial name: cyclosophoran, cyclic β-1,2-glucan, cyclic b-glucan
Compound class: EPS, glucan, cyclic b-glucan
Contained glycoepitopes: IEDB_140628,IEDB_142488,IEDB_146664,IEDB_983931,SB_192

• Article ID: 2601
  Breedveld MW, Cremers HCJC, Batley M, Posthumus MA, Zevenhuizen LPTM, Wijffelman CA, Zehnder AJB "Polysaccharide synthesis in relation to nodulation behavior of Rhizobium leguminosarum" - Journal of Bacteriology 175(3) (1993) 750-757
  

  In this study, we characterized four Tn5 mutants derived from Rhizobium leguminosarum RBL5515 with respect to synthesis and secretion of cellulose fibrils, extracellular polysaccharides (EPS), capsular polysaccharides, and cyclic β-(1,2)-glucans. One mutant, strain RBL5515 exo-344::Tn5, synthesizes residual amounts of EPS, the repeating unit of which lacks the terminal galactose molecule and the substituents attached to it. On basis of the polysaccharide production pattern of strain RBL5515 exo-344::Tn5, the structural features of the polysaccharides synthesized, and the results of an analysis of the enzyme activities involved, we hypothesize that this strain is affected in a galactose transferase involved in the synthesis of EPS only. All four mutants failed to nodulate plants belonging to the pea cross-inoculation group; on Vicia sativa they induced root hair deformation and rare abortive infection threads. All of the mutants appeared to be pleiotropic, since in addition to defects in the synthesis of EPS, lipopolysaccharide, and/or capsular polysaccharides significant increases in the synthesis and secretion of cyclic β-(1,2)-glucans were observed. We concluded that it is impossible to correlate a defect in the synthesis of a particular polysaccharide with nodulation characteristics.

  NCBI PubMed ID: 8423148
  Journal NLM ID: 2985120R
  Publisher: American Society for Microbiology
  Institutions: Department of Microbiology, Agricultural University, Wageningen, The Netherlands., Department of Microbiology, Agricultural University, Wageningen, The Netherlands
  
   
  
  Rhizobium leguminosarum
  CSDB ID 131792 (all data & tools)
• Article ID: 3695
  Guidolin LS, Ciocchini AE, Inon d, Ugalde RA "Functional mapping of Brucella abortus cyclic beta-1,2-glucan synthase: identification of the protein domain required for cyclization" - Journal of Bacteriology 191(4) (2009) 1230-1238
  

  Cyclic β-1,2-glucans (CβG) are periplasmic homopolysaccharides that have been shown to play an important role in several symbiotic and pathogenic relationships. Cyclic β-1,2-glucan synthase (Cgs), the enzyme responsible for the synthesis of CβG, is an integral membrane polyfunctional protein that catalyzes the four enzymatic activities (initiation, elongation, phosphorolysis, and cyclization) required for the synthesis of CβG. Recently, we have identified the glycosyltransferase and the β-1,2-glucooligosaccharide phosphorylase domains of Brucella abortus Cgs. In this study, we performed large-scale linker-scanning mutagenesis to gain further insight into the functional domains of Cgs. This analysis allowed us to construct a functional map of the enzyme and led to the identification of the minimal region required for the catalysis of initiation and elongation reactions. In addition, we identified the Cgs region (residues 991 to 1544) as being the protein domain required for cyclization and demonstrated that upon cyclization and releasing of the CβG, one or more glucose residues remain attached to the protein intermediate that serves as a primer for the next round of CβG synthesis. Finally, our results indicate that the overall control of the degree of polymerization of CβG is the result of a balance between elongation, phosphorolysis, and cyclization reactions

  Brucella abortus, Glucosyltransferases, beta-glucans

  NCBI PubMed ID: 19074375
  Publication DOI: 10.1128/JB.01108-08
  Journal NLM ID: 2985120R
  Publisher: American Society for Microbiology
  Correspondence: rugalde@iib.unsam.edu.ar
  Institutions: Instituto de Investigaciones Biotecnologicas, Universidad Nacional de San Martin, Buenos Aires, Argentina
  Methods: Western blotting, genetic methods, biochemical methods
  
   
  
  Brucella abortus
  CSDB ID 23707 (all data & tools)
• Article ID: 4332
  Komaniecka I, Choma A "Isolation and characterization of periplasmic cyclic β-glucans of Azorhizobium caulinodans" - FEMS Microbiology Letters 227(2) (2003) 263-269
  

  Oligoglucose molecules isolated from Azorhizobium caulinodans were characterized by compositional analysis, Smith degradation, matrix-assisted laser desorption/ionization time of flight mass spectrometry, and (1)H and (13)C nuclear magnetic resonance analysis. A. caulinodans produced nonbranched and unsubstituted cyclic glucans composed solely of glucose, with the degree of polymerization ranging from 10 to 13. A major fraction of the periplasmic glucans contains 11 glucose residues within rings. The glucose residues are linked by β-(1,3) and β-(1,6) glycosidic bonds. These molecules seem to be quite similar to the periplasmic β-(1,3);(1,6)-glucans synthesized by the Bradyrhizobium strain and are substantially different from the cyclic β-(1,2)-glucans produced by Agrobacterium and Sinorhizobium species. Azorhizobial cyclic glucan synthesis is not osmoregulated. The response to the osmotic stress in Azorhizobium can be regulated similarly to Brucella spp. It is probable that the biosynthesis of β-glucans is subject to the feedback control mechanism.

  nuclear magnetic resonance, Azorhizobium caulinodans, osmoregulation, Cyclic β-glucan, Matrix-assisted laser desorption/ionization time of flight

  NCBI PubMed ID: 14592718
  Journal NLM ID: 7705721
  Publisher: Blackwell Publishing
  Correspondence: ikoma@biotop.umcs.lublin.pl
  Institutions: Department of General Microbiology, Maria Curie-Sklodowska University, 19 Akademicka St., 20-033, Lublin, Poland
  Methods: 13C NMR, 1H NMR, NMR-2D, GC-MS, acid hydrolysis, Smith degradation, MALDI-TOF MS, composition analysis, NMR-1D
  
   
  
  Sinorhizobium meliloti, Agrobacterium tumefaciens
  CSDB ID 27214 (all data & tools)
• Article ID: 4574
  Martirosyan A, Pérez-Gutiérrez C, Banchereau R, Dutartre H, Lecine P, Dullaers M, Mello M, Salcedo SP, Muller A, Leserman L, Levy Y, Zurawski G, Zurawski S, Moreno E, Moriyón I, Klechevsky E, Banchereau J, Oh S, Gorvel JP "Brucella β 1,2 cyclic glucan is an activator of human and mouse dendritic cells" - PLoS Pathogens 8(11) (2012) e1002983
  

  Bacterial cyclic glucans are glucose polymers that concentrate within the periplasm of alphaproteobacteria. These molecules are necessary to maintain the homeostasis of the cell envelope by contributing to the osmolarity of Gram negative bacteria. Here, we demonstrate that Brucella β 1,2 cyclic glucans are potent activators of human and mouse dendritic cells. Dendritic cells activation by Brucella β 1,2 cyclic glucans requires TLR4, MyD88 and TRIF, but not CD14. The Brucella cyclic glucans showed neither toxicity nor immunogenicity compared to LPS and triggered antigen-specific CD8(+) T cell responses in vivo. These cyclic glucans also enhanced antigen-specific CD4(+) and CD8(+) T cell responses including cross-presentation by different human DC subsets. Brucella β 1,2 cyclic glucans increased the memory CD4(+) T cell responses of blood mononuclear cells exposed to recombinant fusion proteins composed of anti-CD40 antibody and antigens from both hepatitis C virus and Mycobacterium tuberculosis. Thus cyclic glucans represent a new class of adjuvants, which might contribute to the development of effective antimicrobial therapies

  Brucella, β-1, dendritic cells, 2 cyclic glucans

  NCBI PubMed ID: 23166489
  Publication DOI: 10.1371/journal.ppat.1002983
  Journal NLM ID: 101238921
  Publisher: San Francisco, CA: Public Library of Science
  Correspondence: gorvel@ciml.univ-mrs.fr
  Institutions: Centre d'Immunologie de Marseille-Luminy, Aix-Marseille University, UM2, Marseille, France
  Methods: MALDI-TOF MS, biological assays, serological methods, genetic methods
  
   
  
  Brucella melitensis
  CSDB ID 29274 (all data & tools)
• Article ID: 5407
  Breedveld MW, Miller KJ "Cyclic beta-glucans of members of the family Rhizobiaceae" - Microbiological Reviews 58(2) (1994) 145-161
  

  Cyclic β-glucans are low-molecular-weight cell surface carbohydrates that are found almost exclusively in bacteria of the Rhizobiaceae family. These glucans are major cellular constituents, and under certain culture conditions their levels may reach up to 20% of the total cellular dry weight. In Agrobacterium and Rhizobium species, these molecules contain between 17 and 40 glucose residues linked solely by β-(1,2) glycosidic bonds. In Bradyrhizobium species, the cyclic β-glucans are smaller (10 to 13 glucose residues) and contain glucose linked by both β-(1,6) and β-(1,3) glycosidic bonds. In some rhizobial strains, the cyclic β-glucans are unsubstituted, whereas in other rhizobia these molecules may become highly substituted with moieties such as sn-1-phosphoglycerol. To date, two genetic loci specifically associated with cyclic β-glucan biosynthesis have been identified in Rhizobium (ndvA and ndvB) and Agrobacterium (chvA and chvB) species. Mutants with mutations at these loci have been shown to be impaired in their ability to grow in hypoosmotic media, have numerous alterations in their cell surface properties, and are also impaired in their ability to infect plants. The present review will examine the structure and occurrence of the cyclic β-glucans in a variety of species of the Rhizobiaceae. The possible functions of these unique molecules in the free-living bacteria as well as during plant infection will be discussed.

  biosynthesis, structure, Rhizobiaceae, β-Glucans, Biological Transport

  NCBI PubMed ID: 8078434
  Journal NLM ID: 7806086
  Institutions: Department of Food Science, Pennsylvania State University, University Park 16802
  
   
  
  Rhizobium leguminosarum, Agrobacterium tumefaciens
  CSDB ID 976 (all data & tools)
• Article ID: 5851
  Szpakowska N, Kowalczyk A, Jafra S, Kaczyński Z "The chemical structure of polysaccharides isolated from the Ochrobactrum rhizosphaerae PR17(T)" - Carbohydrate Research 497 (2020) 108136
  

  The bacteria from Ochrobactrum genus are commonly found in the soil and association with the roots of plants. The O-polysaccharide and the glucan were isolated from the Ochrobactrum rhizosphaerae PR17(T) strain. Purified polysaccharides were analysed using chemical methods and NMR spectroscopy. Sugar and absolute configuration assignment combined with NMR data revealed the chemical structure of the repeating unit of the O- [formula: see text].

  NMR, structure, O-polysaccharide, glucan, Ochrobactrum rhizosphaerae PR17(T)

  NCBI PubMed ID: 32889436
  Publication DOI: 10.1016/j.carres.2020.108136
  Journal NLM ID: 0043535
  Publisher: Elsevier
  Correspondence: zbigniew.kaczynski@ug.edu.pl
  Institutions: Faculty of Chemistry, University of Gdansk, Gdansk, Poland, Laboratory of Biological Plant Protection, Intercollegiate Faculty of Biotechnology of University of Gdansk and Medical University of Gdansk, University of Gdansk, Gdansk, Poland
  Methods: 13C NMR, 1H NMR, NMR-2D, GC-MS, acid hydrolysis, GLC, composition analysis, acetylation, SEC, reduction with NaBH4
  
   
  
  Ochrobactrum rhizosphaerae PR17(T)
  CSDB ID 7593 (all data & tools)

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Structure type: polymer chemical repeating unit
Compound class: O-polysaccharide
Contained glycoepitopes: IEDB_115015,IEDB_130648,IEDB_137473,IEDB_142489,IEDB_149135,SB_86

• Article ID: 5851
  Szpakowska N, Kowalczyk A, Jafra S, Kaczyński Z "The chemical structure of polysaccharides isolated from the Ochrobactrum rhizosphaerae PR17(T)" - Carbohydrate Research 497 (2020) 108136
  

  The bacteria from Ochrobactrum genus are commonly found in the soil and association with the roots of plants. The O-polysaccharide and the glucan were isolated from the Ochrobactrum rhizosphaerae PR17(T) strain. Purified polysaccharides were analysed using chemical methods and NMR spectroscopy. Sugar and absolute configuration assignment combined with NMR data revealed the chemical structure of the repeating unit of the O- [formula: see text].

  NMR, structure, O-polysaccharide, glucan, Ochrobactrum rhizosphaerae PR17(T)

  NCBI PubMed ID: 32889436
  Publication DOI: 10.1016/j.carres.2020.108136
  Journal NLM ID: 0043535
  Publisher: Elsevier
  Correspondence: zbigniew.kaczynski@ug.edu.pl
  Institutions: Faculty of Chemistry, University of Gdansk, Gdansk, Poland, Laboratory of Biological Plant Protection, Intercollegiate Faculty of Biotechnology of University of Gdansk and Medical University of Gdansk, University of Gdansk, Gdansk, Poland
  Methods: 13C NMR, 1H NMR, NMR-2D, GC-MS, acid hydrolysis, GLC, composition analysis, acetylation, SEC, reduction with NaBH4
  
   
  
  Ochrobactrum rhizosphaerae PR17(T)
  CSDB ID 32210 (all data & tools)