Unravelling Glucan Recognition Systems by Glycome Microarrays Using the Designer Approach and Mass Spectrometry.
Palma, A. S., Liu, Y., Zhang, H., Zhang, Y., McCleary, B. V., Yu, G., Huang, Q., Guidolin, L. S., Ciocchini, A. E., Torosantucci, A., Wang, D., Carvalho, A. L., Fontes, C. M. G. A., Mulloy, B., Childs, R. A., Feizi,T. & Chai, W. (2015). Mol. Cell Proteomics, 14(4), 974-988.
Glucans are polymers of D-glucose with differing linkages in linear or branched sequences. They are constituents of microbial and plant cell-walls and involved in important bio-recognition processes, including immunomodulation, anticancer activities, pathogen virulence, and plant cell-wall biodegradation. Translational possibilities for these activities in medicine and biotechnology are considerable. High-throughput micro-methods are needed to screen proteins for recognition of specific glucan sequences as a lead to structure–function studies and their exploitation. We describe construction of a “glucome” microarray, the first sequence-defined glycome-scale microarray, using a “designer” approach from targeted ligand-bearing glucans in conjunction with a novel high-sensitivity mass spectrometric sequencing method, as a screening tool to assign glucan recognition motifs. The glucome microarray comprises 153 oligosaccharide probes with high purity, representing major sequences in glucans. Negative-ion electrospray tandem mass spectrometry with collision-induced dissociation was used for complete linkage analysis of gluco-oligosaccharides in linear “homo” and “hetero” and branched sequences. The system is validated using antibodies and carbohydrate-binding modules known to target α- or β-glucans in different biological contexts, extending knowledge on their specificities, and applied to reveal new information on glucan recognition by two signaling molecules of the immune system against pathogens: Dectin-1 and DC-SIGN. The sequencing of the glucan oligosaccharides by the MS method and their interrogation on the microarrays provides detailed information on linkage, sequence and chain length requirements of glucan-recognizing proteins, and are a sensitive means of revealing unsuspected sequences in the polysaccharides.
Molecular characterization of polysaccharides in hot-water extracts of Ganoderma lucidum fruiting bodies.
Chang, Y. W. & Lu, T. J. (2004). Journal of Food and Drug Analysis, 12(1), 59-67.
Polysaccharide components in hot-water extract of Ganoderma lucidum fruiting bodies were separated and their molecular weights and distribution profiles were measured using high-performance size-exclusion chromatography with multi-angle laser light scattering detection (HPSEC-MALLS). Three polysaccharide groups were found in the extract with a weight percentage of 31, 46 and 23% respectively. The weight-average molecular weights of these groups were 2.08 x 106, 2.3 x 104, and 1.2 x 104 g/mol, respectively. The representative fractions of these 3 groups were obtained using differential precipitation with ethanol at 20, 60 and 80% (v/v) concentrations for further property study. The first group that had the largest molecular size was branched (1→3)-β-D-glucan with single β-D glucosyl side chains at the O-6 positions, as revealed from sugar composition analysis, aniline blue assay and 1H- and 13C-NMR spectroscopy. (1→3, 1→6)-β-D-glucan was the major active polysaccharide and showed significant tumor necrosis factor-α (TNF-α) releasing stimulation activity from human mononuclear cells (MNC). The glucan was slightly soluble in water at ambient temperature. The second and third groups that showed slight modulating activity consisted of D-glucose, D-galactose and D-mannose at different ratios. Aggregation of polysaccharide molecules was also revealed by HPSEC-MALLS study.
Endo-β-1,3-glucanase GLU1, from the fruiting body of Lentinula edodes, belongs to a new glycoside hydrolase family.
Sakamoto, Y., Nakade, K. & Konno, N. (2011). Applied and Environmental Microbiology, 77(23), 8350-8354.
The cell wall of the fruiting body of the mushroom Lentinula edodes is degraded after harvesting by enzymes such as β-1,3-glucanase. In this study, a novel endo-type β-1,3-glucanase, GLU1, was purified from L. edodes fruiting bodies after harvesting. The gene encoding it, glu1, was isolated by rapid amplification of cDNA ends (RACE)-PCR using primers designed from the N-terminal amino acid sequence of GLU1. The putative amino acid sequence of the mature protein contained 247 amino acid residues with a molecular mass of 26 kDa and a pI of 3.87, and recombinant GLU1 expressed in Pichia pastoris exhibited β-1,3-glucanase activity. GLU1 catalyzed depolymerization of glucans composed of β-1,3-linked main chains, and reaction product analysis by thin-layer chromatography (TLC) clearly indicated that the enzyme had an endolytic mode. However, the amino acid sequence of GLU1 showed no significant similarity to known glycoside hydrolases. GLU1 has similarity to several hypothetical proteins in fungi, and GLU1 and highly similar proteins should be classified as a novel glycoside hydrolase family (GH128).
Modulation of the immune response of porcine neutrophils by different β-glucan preparations.
Juul-Madsen, H. R., Norup, L. & Lærke, H. N. (2010). Livestock science, 133(1), 249-252.
β-glucans of bacterial and fungal origin are known immuno-modulators, but data in the literature also indicate that lichen and cereal-derived β-glucans may have immuno-modulatory functions. The aim of the current study was to test the effect of different sources of β-glucans on neutrophils in an ex-vivo whole blood stimulation assay. Whole blood samples were either treated with curdlan, a linear β-(1→3)-D-glucan from the non-pathogenic Alcaligenes faecalis, lichenan, a mixed linked β-(1→3),(1→4)-D-glucan from Islandic moss (Cetraria islandica) or zymosan, prepared from yeast cell walls and being rich in branched β–(1→3),(1→6)–D-glucan. The blood cell were either stimulated alone or in combination with lipopolysaccharide (LPS) and compared with LPS-treated and untreated control samples. Preliminary results show that Zymosan, had a different effect than lichenan and curdlan, on the surface expression of Toll-like Receptor (TLR) 2 and 4, but not significantly on the signal regulatory protein SIRPα after a stimulation either alone or in combination with LPS. Thus, branching may appear to be important for the different effect, but an effect of impurities in the Zymosan preparation cannot be ruled out.
Plant production of anti‐β‐glucan antibodies for immunotherapy of fungal infections in humans.
Capodicasa, C., Chiani, P., Bromuro, C., De Bernardis, F., Catellani, M., Palma, A. S., Liu, Y., Feiz, T., Cassone, A., Benvenuto, E. & Torosantucci, A. (2011). Plant Biotechnology Journal, 9(7), 776-787.
There is an increasing interest in the development of therapeutic antibodies (Ab) to improve the control of fungal pathogens, but none of these reagents is available for clinical use. We previously described a murine monoclonal antibody (mAb 2G8) targeting β-glucan, a cell wall polysaccharide common to most pathogenic fungi, which conferred significant protection against Candida albicans, Aspergillus fumigatus and Cryptococcus neoformans in animal models. Transfer of this wide-spectrum, antifungal mAb into the clinical setting would allow the control of most frequent fungal infections in many different categories of patients. To this aim, two chimeric mouse–human Ab derivatives from mAb 2G8, in the format of complete IgG or scFv-Fc, were generated, transiently expressed in Nicotiana benthamiana plants and purified from leaves with high yields (approximately 50 mg Ab/kg of plant tissues). Both recombinant Abs fully retained the β-glucan-binding specificity and the antifungal activities of the cognate murine mAb against C. albicans. In fact, they recognized preferentially β1,3-linked glucan molecules present at the fungal cell surface and directly inhibited the growth of C. albicans and its adhesion to human epithelial cells in vitro. In addition, both the IgG and the scFv-Fc promoted C. albicans killing by isolated, human polymorphonuclear neutrophils in ex vivo assays and conferred significant antifungal protection in animal models of systemic or vulvovaginal C. albicans infection. These recombinant Abs represent valuable molecules for developing novel, plant-derived immunotherapeutics against candidiasis and, possibly, other fungal diseases.
Characterization of a broad-specificity β-glucanase acting on β-(1,3)-, β-(1,4)-, and β-(1,6)-glucans that defines a new glycoside hydrolase family.
Lafond, M., Navarro, D., Haon, M., Couturier, M. & Berrin, J. G. (2012). Applied and Environmental Microbiology, 78(24), 8540-8546.
Here we report the cloning of the Pa_3_10940 gene from the coprophilic fungus Podospora anserina, which encodes a C-terminal family 1 carbohydrate binding module (CBM1) linked to a domain of unknown function. The function of the gene was investigated by expression of the full-length protein and a truncated derivative without the CBM1 domain in the yeast Pichia pastoris. Using a library of polysaccharides of different origins, we demonstrated that the full-length enzyme displays activity toward a broad range of β-glucan polysaccharides, including laminarin, curdlan, pachyman, lichenan, pustulan, and cellulosic derivatives. Analysis of the products released from polysaccharides revealed that this β-glucanase is an exo-acting enzyme on β-(1,3)- and β-(1,6)-linked glucan substrates and an endo-acting enzyme on β-(1,4)-linked glucan substrates. Hydrolysis of short β-(1,3), β-(1,4), and β-(1,3)/β-(1,4) gluco-oligosaccharides confirmed this striking feature and revealed that the enzyme performs in an exo-type mode on the nonreducing end of gluco-oligosaccharides. Excision of the CBM1 domain resulted in an inactive enzyme on all substrates tested. To our knowledge, this is the first report of an enzyme that displays bifunctional exo-β-(1,3)/(1,6) and endo-β-(1,4) activities toward beta-glucans and therefore cannot readily be assigned to existing Enzyme Commission groups. The amino acid sequence has high sequence identity to hypothetical proteins within the fungal taxa and thus defines a new family of glycoside hydrolases, the GH131 family.
Characterization and three-dimensional structures of two distinct bacterial xyloglucanases from families GH5 and GH12.
Gloster, T. M., Ibatullin, F. M., Macauley, K., Eklöf, J. M., Roberts, S., Turkenburg, J. P., Bjørnvad, M. E., Jørgensen, P. L., Danielsen, S., Johansen, K. S., Borchert, T. V., Wilson, K. S., Brumer, H. & Davies, G. J. (2007). Journal of Biological Chemistry, 282(26), 19177-19189.
The plant cell wall is a complex material in which the cellulose microfibrils are embedded within a mesh of other polysaccharides, some of which are loosely termed “hemicellulose.” One such hemicellulose is xyloglucan, which displays a β-1,4-linked D-glucose backbone substituted with xylose, galactose, and occasionally fucose moieties. Both xyloglucan and the enzymes responsible for its modification and degradation are finding increasing prominence, reflecting both the drive for enzymatic biomass conversion, their role in detergent applications, and the utility of modified xyloglucans for cellulose fiber modification. Here we present the enzymatic characterization and three-dimensional structures in ligand-free and xyloglucan-oligosaccharide complexed forms of two distinct xyloglucanases from glycoside hydrolase families GH5 and GH12. The enzymes, Paenibacillus pabuli XG5 and Bacillus licheniformis XG12, both display open active center grooves grafted upon their respective (β/α)8 and β-jelly roll folds, in which the side chain decorations of xyloglucan may be accommodated. For the β-jelly roll enzyme topology of GH12, binding of xylosyl and pendant galactosyl moieties is tolerated, but the enzyme is similarly competent in the degradation of unbranched glucans. In the case of the (β/α)8 GH5 enzyme, kinetically productive interactions are made with both xylose and galactose substituents, as reflected in both a high specific activity on xyloglucan and the kinetics of a series of aryl glycosides. The differential strategies for the accommodation of the side chains of xyloglucan presumably facilitate the action of these microbial hydrolases in milieus where diverse and differently substituted substrates may be encountered.
An Endoglucanase, EglA, from the Hyperthermophilic Archaeon Pyrococcus furiosus Hydrolyzes β-1,4 Bonds in Mixed-Linkage (1→3),(1→4)-β-D-Glucans and Cellulose.
Bauer, M. W., Driskill, L. E., Callen, W., Snead, M. A., Mathur, E. J. & Kelly, R. M. (1999). Journal of Bacteriology, 181(1), 284-290.
The eglA gene, encoding a thermostable endoglucanase from the hyperthermophilic archaeon Pyrococcus furiosus, was cloned and expressed in Escherichia coli. The nucleotide sequence of the gene predicts a 319-amino-acid protein with a calculated molecular mass of 35.9 kDa. The endoglucanase has a 19-amino-acid signal peptide but not cellulose-binding domain. The P. furiosus endoglucanase has significant amino acid sequence similarities, including the conserved catalytic nucleophile and proton donor, with endoglucanases from glucosyl hydrolase family 12. The purified recombinant enzyme hydrolyzed β-1,4 but not β-1,3 glucosidic linkages and had the highest specific activity on cellopentaose (degree of polymerization [DP] = 5) and cellohexaose (DP = 6) oligosaccharides. To a lesser extent, EglA also hydrolyzed shorter cellodextrins (DP < 5) as well as the amorphous portions of polysaccharides which contain only β-1,4 bonds such as carboxymethyl cellulose, microcrystalline cellulose, Whatman paper, and cotton linter. The highest specific activity toward polysaccharides occurred with mixed-linkage β-glucans such as barley β-glucan and lichenan. Kinetics studies with cellooliogsaccharides and p-nitrophenyl-cellooligosaccharides indicated that the enzyme had three glucose binding subsites (−I, −II, and −III) for the nonreducing end and two glucose binding subsites (+I and +II) for the reducing end from the scissile glycosidic linkage. The enzyme had temperature and pH optima of 100°C and 6.0, respectively; a half-life of 40 h at 95°C; and a denaturing temperature of 112°C as determined by differential scanning calorimetry. The discovery of a thermostable enzyme with this substrate specificity has implications for both the evolution of enzymes involved in polysaccharide hydrolysis and the occurrence of growth substrates in hydrothermal vent environments.
Ligands for the β-glucan receptor, Dectin-1, assigned using “designer” microarrays of oligosaccharide probes (neoglycolipids) generated from glucan polysaccharides.
Palma, A. S., Feizi, T., Zhang, Y., Stoll, M. S., Lawson, A. M., Díaz-Rodríguez, E., Campanero-Rhodes, M. A., Costa, J. L., Gordon, S., Brown, G. D. & Chai, W. (2006). Journal of Biological Chemistry, 281(9), 5771-5779.
Dectin-1 is a C-type lectin-like receptor on leukocytes that mediates phagocytosis and inflammatory mediator production in innate immunity to fungal pathogens. Dectin-1 lacks residues involved in calcium ligation that mediates carbohydrate-binding by classical C-type lectins; nevertheless, it binds zymosan, a particulate β-glucan-rich extract of Saccharomyces cerevisiae, and binding is inhibited by polysaccharides rich in β1,3- or both β1,3- and β1,6-linked glucose. The oligosaccharide ligands on glucans recognized by Dectin-1 have not yet been delineated precisely. It is also not known whether Dectin-1 can interact with other types of carbohydrates. We have investigated this, since Dectin-1 shows glucan-independent binding to a subset of T-lymphocytes and is involved in triggering their proliferation. Here we assign oligosaccharide ligands for Dectin-1 using the neoglycolipid-based oligosaccharide microarray technology, a unique approach for constructing microarrays of lipid-linked oligosaccharide probes from desired sources. We generate “designer” microarrays from three glucan polysaccharides, a neutral soluble glucan isolated from S. cerevisiae and two bacterial glucans, curdlan from Alcaligenes faecalis and pustulan from Umbilicaria papullosa, and use these in conjunction with 187 diverse, sequence-defined, predominantly mammalian-type, oligosaccharide probes. Among these, Dectin-1 binding is detected exclusively to 1,3-linked glucose oligomers, the minimum length required for detectable binding being a 10- or 11-mer. Thus, the ligands assigned so far are exogenous rather than endogenous. We further show that Dectin-1 ligands, 11-13 gluco-oligomers, in clustered form (displayed on liposomes), mimic the macromolecular β-glucans and compete with zymosan binding and triggering of tumor necrosis factor-α secretion by a Dectin-1-expressing macrophage cell line.
Characterization of an Endo-Processive-Type Xyloglucanase Having a β-1,4-Glucan-Binding Module and an Endo-Type Xyloglucanase from Streptomyces avermitilis.
Ichinose, H., Araki, Y., Michikawa, M., Harazono, K., Yaoi, K., Karita, S. & Kaneko, S. (2012). Applied and Environmental Microbiology, 78(22), 7939-7945.
We cloned two glycoside hydrolase family 74 genes, the sav_1856 gene and the sav_2574 gene, from Streptomyces avermitilis NBRC14893 and characterized the resultant recombinant proteins. The sav_1856 gene product (SaGH74A) consisted of a catalytic domain and a family 2 carbohydrate-binding module at the C terminus, while the sav_2574 gene product (SaGH74B) consisted of only a catalytic domain. SaGH74A and SaGH74B were expressed successfully and had molecular masses of 92 and 78 kDa, respectively. Both recombinant proteins were xyloglucanases. SaGH74A had optimal activity at 60°C and pH 5.5, while SaGH74B had optimal activity at 55°C and pH 6.0. SaGH74A was stable over a broad pH range (pH 4.5 to 9.0), whereas SaGH74B was stable over a relatively narrow pH range (pH 6.0 to 6.5). Analysis of the hydrolysis products of tamarind xyloglucan and xyloglucan-derived oligosaccharides indicated that SaGH74A was endo-processive, while SaGH74B was a typical endo-enzyme. The C terminus of SaGH74A, which was annotated as a carbohydrate-binding module, bound to β-1,4-linked glucan-containing soluble polysaccharides such as hydroxyethyl cellulose, barley glucan, and xyloglucan.
Comparison of β-1,3-glucanase production by Botryosphaeria rhodina MAMB-05 and Trichoderma harzianum Rifai and its optimization using a statistical mixture-design.
Giese, E. C., Dekker, R. F. H., Scarminio, I. S., Barbosa, A. M. & da Silva, R. (2011). Biochemical Engineering Journal, 53(2), 239-243.
Botryosphaeria rhodina MAMB-05 produced β-1,3-glucanases and botryosphaeran when grown on glucose, while Trichoderma harzianum Rifai only produced the enzyme. A comparison of long-term cultivation (300 h) by B. rhodina demonstrated a correlation between the formation of botryosphaeran (48 h) and its consumption (after 108 h), and de-repression of β-1,3-glucanase synthesis when glucose was depleted from the nutrient medium, whereas for T. harzianum enzyme production commenced during exponential growth. Growth profiles and levels of β-1,3-glucanases produced by both fungi on botryosphaeran also differed, as well as the production of β-1,3-glucanases and β-1,6-glucanases on glucose, lactose, laminarin, botryosphaeran, lasiodiplodan, curdlan, Brewer's yeast powder and lyophilized fungal mycelium, which were dependent upon the carbon source used. A statistical mixture-design used to optimize β-1,3-glucanase production by both fungi evaluated botryosphaeran, glucose and lactose concentrations as variables. For B. rhodina, glucose and lactose promoted enzyme production at the same levels (2.30 U mL-1), whereas botryosphaeran added to these substrates exerted a synergic effect favorable for β-glucanase production by T. harzianum (4.25 U mL-1).