Versatile high resolution oligosaccharide microarrays for plant glycobiology and cell wall research.
Pedersen, H. L., Fangel, J. U., McCleary, B., Ruzanski, C., Rydahl, M. G., Ralet, M. C., Farkas, V., Von Schantz, L., Marcus, S. E., Andersen, M.C. F., Field, R., Ohlin, M., Knox, J. P., Clausen, M. H. & Willats, W. G. T. (2012). Journal of Biological Chemistry, 287(47), 39429-39438.
Microarrays are powerful tools for high throughput analysis, and hundreds or thousands of molecular interactions can be assessed simultaneously using very small amounts of analytes. Nucleotide microarrays are well established in plant research, but carbohydrate microarrays are much less established, and one reason for this is a lack of suitable glycans with which to populate arrays. Polysaccharide microarrays are relatively easy to produce because of the ease of immobilizing large polymers noncovalently onto a variety of microarray surfaces, but they lack analytical resolution because polysaccharides often contain multiple distinct carbohydrate substructures. Microarrays of defined oligosaccharides potentially overcome this problem but are harder to produce because oligosaccharides usually require coupling prior to immobilization. We have assembled a library of well characterized plant oligosaccharides produced either by partial hydrolysis from polysaccharides or by de novo chemical synthesis. Once coupled to protein, these neoglycoconjugates are versatile reagents that can be printed as microarrays onto a variety of slide types and membranes. We show that these microarrays are suitable for the high throughput characterization of the recognition capabilities of monoclonal antibodies, carbohydrate-binding modules, and other oligosaccharide-binding proteins of biological significance and also that they have potential for the characterization of carbohydrate-active enzymes.
Isolation and Properties of Xyloglucanases of Penicillium sp.
Sinitsyna, O. A., Fedorova, E. A., Pravilnikov, A. G., Rozhkova, A. M., Skomarovsky, A. A., Matys, V. Y., Bubnova, T. M., Okunev, O. N., Vinetsky, Y. P. & Sinitsyn, A. P. (2010). Biochemistry (Moscow), 75(1), 41-49.
Using chromatographic technique, xyloglucanase (XG) A (25 kDa, pI 3.5, 12th glycosyl hydrolase family) was isolated from the enzyme complex secreted by the mycelial fungus Penicillium canescens, and xyloglucanases XG 25 (25 kDa, pI 4.1, 12th glycosyl hydrolase family) and XG 70 (70 kDa, pI 3.5, 74th glycosyl hydrolase family) were isolated from the enzyme complex of Penicillium verruculosum. Properties of the isolated enzymes (substrate specificity, optimal ranges of pH and temperature for enzyme activity and stability, effect of metal ions on catalytic activity) were compared with the properties of xyloglucanases XG 32 of Aspergillus japonicus, XG 78 of Chrysosporium lucknowense, and XG of Trichoderma reesei. The gene xegA encoding XG A of P. canescens was isolated, and the amino acid sequence of the corresponding protein was determined.
Isolation and properties of fungal β-glucosidases.
Korotkova, O. G., Semenova, M. V., Morozova, V. V., Zorov, I. N., Sokolova, L. M., Bubnova, T. M., Okunev, O. N. & Sinitsyn, A. P. (2009). Biochemistry (Moscow), 74(5), 569-577
Using chromatography on different matrixes, three β-glucosidases (120, 116, and 70 kDa) were isolated from enzymatic complexes of the mycelial fungi Aspergillus japonicus, Penicillium verruculosum, and Trichoderma reesei, respectively. The enzymes were identified by MALDI-TOF mass-spectrometry. Substrate specificity, kinetic parameters for hydrolysis of specific substrates, ability to catalyze the transglucosidation reaction, dependence of the enzymatic activity on pH and temperature, stability of the enzymes at different temperatures, adsorption ability on insoluble cellulose, and the influence of glucose on catalytic properties of the enzymes were investigated. According to the substrate specificity, the enzymes were shown to belong to two groups: i) β-glucosidase of A. japonicus exhibiting high specific activity to the low molecular weight substrates cellobiose and pNPG (the specific activity towards cellobiose was higher than towards pNPG) and low activity towards polysaccharide substrates (β-glucan from barley and laminarin); ii) β-glucosidases from P. verruculosum and T. reesei exhibiting relatively high activity to polysaccharide substrates and lower activity to low molecular weight substrates (activity to cellobiose was lower than to pNPG).
Structure of the fungal β-glucan‐binding immune receptor dectin‐1: Implications for function.
Brown, J., O'Callaghan, C. A., Marshall, A. S. J., Gilbert, R. J. C., Siebold, C., Gordon, S., Brown, G. D. & Jones, E. Y. (2007). Protein Science, 16(6), 1042-1052.
The murine molecule dectin-1 (known as the β-glucan receptor in humans) is an immune cell surface receptor implicated in the immunological defense against fungal pathogens. Sequence analysis has indicated that the dectin-1 extracellular domain is a C-type lectin-like domain, and functional studies have established that it binds fungal β-glucans. We report several dectin-1 crystal structures, including a high-resolution structure and a 2.8 Å resolution structure in which a short soaked natural β-glucan is trapped in the crystal lattice. In vitro characterization of dectin-1 in the presence of its natural ligand indicates higher-order complex formation between dectin-1 and β-glucans. These combined structural and biophysical data considerably extend the current knowledge of dectin-1 structure and function, and suggest potential mechanisms of defense against fungal pathogens.
The maltodextrin transport system and metabolism in Lactobacillus acidophilus NCFM and production of novel α‐glucosides through reverse phosphorolysis by maltose phosphorylase.
Nakai, H., Baumann, M. J., Petersen, B. O., Westphal, Y., Schols, H., Dilokpimol, A., Hachem, M. A., Lahtinen, S. J., Duus, J. Ø. & Svensson, B. (2009). FEBS Journal, 276(24), 7353-7365.
A gene cluster involved in maltodextrin transport and metabolism was identified in the genome of Lactobacillus acidophilus NCFM, which encoded a maltodextrin-binding protein, three maltodextrin ATP-binding cassette transporters and five glycosidases, all under the control of a transcriptional regulator of the LacI-GalR family. Enzymatic properties are described for recombinant maltose phosphorylase (MalP) of glycoside hydrolase family 65 (GH65), which is encoded by malP (GenBank: AAV43670.1) of this gene cluster and produced in Escherichia coli. MalP catalyses phosphorolysis of maltose with inversion of the anomeric configuration releasing β-glucose 1-phosphate (β-Glc 1-P) and glucose. The broad specificity of the aglycone binding site was demonstrated by products formed in reverse phosphorolysis using various carbohydrate acceptor substrates and β-Glc 1-P as the donor. MalP showed strong preference for monosaccharide acceptors with equatorial 3-OH and 4-OH, such as glucose and mannose, and also reacted with 2-deoxy glucosamine and 2-deoxy N-acetyl glucosamine. By contrast, none of the tested di- and trisaccharides served as acceptors. Disaccharide yields obtained from 50 mM β-Glc 1-P and 50 mM glucose, glucosamine, N-acetyl glucosamine, mannose, xylose or L-fucose were 99, 80, 53, 93, 81 and 13%, respectively. Product structures were determined by NMR and ESI-MS to be α-Glcp-(1→4)-Glcp (maltose), α-Glcp-(1→4)-GlcNp (maltosamine), α-Glcp-(1→4)-GlcNAcp (N-acetyl maltosamine), α-Glcp-(1→4)-Manp, α-Glcp-(1→4)-Xylp and α-Glcp-(1→4)-L-Fucp, the three latter being novel compounds. Modelling using L. brevis GH65 as the template and superimposition of acarbose from a complex with Thermoanaerobacterium thermosaccharolyticum GH15 glucoamylase suggested that loop 3 of MalP involved in substrate recognition blocked the binding of candidate acceptors larger than monosaccharides.
Purification and Characterization of a Thermostable Laminarinase from Penicillium rolfsii c3-2 (1) IBRL.
Lee, K. C., Arai, T., Ibrahim, D., Kosugi, A., Prawitwong, P., Lan, D., Murata, Y. & Mori, Y. (2014). BioResources, 9(1), 1072-1084
A laminarinase (endo-β-1,3-glucanase) was purified to homogeneity from Penicillium rolfsii c3-2(1) IBRL, which was originally produced in liquid culture containing 1% xylan from birchwood, via anion-exchange chromatography, gel filtration on Sephacryl S-100, and hydrophobic interaction chromatography. A single protein band with a molecular weight of 75 kDa was detected by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, which had an optimum catalytic activity at pH 4.0 to 5.0 and 70°C. This purified enzyme was most stable in the pH range 4 to 7, while it was thermostable up to 55°C and retained up to 90% of its activity after 4 h pre-incubation. A substrate laminarin kinetic study yielded estimated Km and Vmax values of 0.0817 mg/mL and 372.2 µmol/min/mg, respectively. Laminari-oligosaccharide degradation, which was analyzed by thin layer chromatography, yielded the major hydrolysis products laminaribiose and glucose.