Tetanus Toxoids Loaded Glucomannosylated Chitosan Based Nanohoming Vaccine Adjuvant with Improved Oral Stability and Immunostimulatory Response.
Harde, H., Agrawal, A. K. & Jain, S. (2015). Pharmaceutical Research, 32(1), 122-134.
Purpose: The present report embarks on rational designing of stable and functionalized chitosan nanoparticles for oral mucosal immunization. Methods: Stable glucomannosylated sCh-GM-NPs were prepared by tandem cross linking method followed by lyophilization. The in vitro stability of antigen and formulation, cellular uptake and immunostimulatory response were assessed by suitable experimental protocol. Results: Stability testing ensured the chemical and conformation permanency of encapsulated TT as well as robustness of sCh-GM-NPs in simulated biological media. The antigen release from sCh-GM-NPs followed initial burst followed by controlled Weibull’s type of release profile. The higher intracellular uptake of sCh-GM-NPs in Raw 264.7 and Caco-2 was concentration and time dependent which mainly attributed to Clathrin and receptor mediated endocytosis via mannose and glucose receptor. The in vivo evaluation in animals revealed that sCh-GM-NPs posed significantly (p < 0.001) higher humoral, mucosal and cellular immune response than other counterparts. More importantly, commercial TT vaccine administered through oral or intramuscular route was unable to elicit all type of immune response. Conclusion: The sCh-GM-NPs could be considered as promising vaccine adjuvant for oral tetanus immunization. Additionally, this technology expected to benefit the design and development of stable peroral formulation for administration of protein, peptides and variety of other antigens.
Divalent toxoids loaded stable chitosan–glucomannan nanoassemblies for efficient systemic, mucosal and cellular immunostimulatory response following oral administration.
Harde, H., Siddhapura, K., Agrawal, A. K. & Jain, S. (2015). International journal of pharmaceutics, 487(1), 292-304.
The present study reports dual tetanus and diphtheria toxoids loaded stable chitosan–glucomannan nanoassemblies (sCh–GM-NAs) formulated using tandem ionic gelation technique for oral mucosal immunization. The stable, lyophilized sCh–GM-NAs exhibited ~152 nm particle size and ~85% EE of both the toxoids. The lyophilized sCh–GM-NAs displayed excellent stability in biomimetic media and preserved chemical, conformation and biological stability of encapsulated toxoids. The higher intracellular APCs uptake of sCh–GM-NAs was concentration and time dependent which may be attributed to the receptor mediated endocytosis via mannose and glucose receptor. The higher Caco-2 uptake of sCh–GM-NAs was further confirmed by ex vivo intestinal uptake studies. The in vivo evaluation revealed that sCh–GM-NAs posed significantly (p < 0.001) higher humoral, mucosal and cellular immune response than other counterparts by eliciting complete protective levels of anti-TT and anti-DT (~0.1 IU/mL) antibodies. Importantly, commercial ‘Dual antigen’ vaccine administered through oral or intramuscular route was unable to elicit all type of immune response. Conclusively, sCh–GM-NAs could be considered as promising vaccine adjuvant for oral mucosal immunization.
A revised architecture of primary cell walls based on biomechanical changes induced by substrate-specific endoglucanases.
Park, Y. B. & Cosgrove, D. J. (2012). Plant Physiology, 158(4), 1933-1943.
Xyloglucan is widely believed to function as a tether between cellulose microfibrils in the primary cell wall, limiting cell enlargement by restricting the ability of microfibrils to separate laterally. To test the biomechanical predictions of this “tethered network” model, we assessed the ability of cucumber (Cucumis sativus) hypocotyl walls to undergo creep (long-term, irreversible extension) in response to three family-12 endo-β-1,4-glucanases that can specifically hydrolyze xyloglucan, cellulose, or both. Xyloglucan-specific endoglucanase (XEG from Aspergillus aculeatus) failed to induce cell wall creep, whereas an endoglucanase that hydrolyzes both xyloglucan and cellulose (Cel12A from Hypocrea jecorina) induced a high creep rate. A cellulose-specific endoglucanase (CEG from Aspergillus niger) did not cause cell wall creep, either by itself or in combination with XEG. Tests with additional enzymes, including a family-5 endoglucanase, confirmed the conclusion that to cause creep, endoglucanases must cut both xyloglucan and cellulose. Similar results were obtained with measurements of elastic and plastic compliance. Both XEG and Cel12A hydrolyzed xyloglucan in intact walls, but Cel12A could hydrolyze a minor xyloglucan compartment recalcitrant to XEG digestion. Xyloglucan involvement in these enzyme responses was confirmed by experiments with Arabidopsis (Arabidopsis thaliana) hypocotyls, where Cel12A induced creep in wild-type but not in xyloglucan-deficient (xxt1/xxt2) walls. Our results are incompatible with the common depiction of xyloglucan as a load-bearing tether spanning the 20- to 40-nm spacing between cellulose microfibrils, but they do implicate a minor xyloglucan component in wall mechanics. The structurally important xyloglucan may be located in limited regions of tight contact between microfibrils.
Trp residue at subsite − 5 plays a critical role in the substrate binding of two protistan GH26 β-mannanases from a termite hindgut.
Hsu, Y., Koizumi, H., Otagiri, M., Moriya, S. & Arioka, M. (2018). Applied Microbiology and Biotechnology, 1-11.
Symbiotic protists in the hindgut of termites provide a novel enzymatic resource for efficient lignocellulytic degradation of plant biomass. In this study, two β-mannanases, RsMan26A and RsMan26B, from a symbiotic protist community of the lower termite, Reticulitermes speratus, were successfully expressed in the methylotrophic yeast, Pichia pastoris. Biochemical characterization experiments demonstrated that both RsMan26A and RsMan26B are endo-acting enzymes and have a very similar substrate specificity, displaying a higher catalytic efficiency to galactomannan from locust bean gum (LBG) and glucomannan than to β-1,4-mannan and highly substituted galactomannan from guar gum. Homology modeling of RsMan26A and RsMan26B revealed that each enzyme displays a long open cleft harboring a unique hydrophobic platform (Trp79) that stacks against the sugar ring at subsite - 5. The Km) values of W79A mutants of RsMan26A and RsMan26B to LBG increased by 4.8-fold and 3.6-fold, respectively, compared with those for the native enzymes, while the kcat) remained unchanged or about 40% of that of the native enzyme, resulting in the decrease in the catalytic efficiency by 4.8-fold and 9.1-fold, respectively. The kinetic values for glucomannan also showed a similar result. These results demonstrate that the Trp residue present near the subsite - 5 has an important role in the recognition of the sugar ring in the substrate.
Stability and ligand promiscuity of type A carbohydrate-binding modules are illustrated by the structure of Spirochaeta thermophila StCBM64C.
Pires, V. M. R., Pereira, P. M. M., Brás, J. L. A., Correia, M., Cardoso, V., Bule, P., Alves, V. D., Najmudin, S., Venditto, I., Ferreira, L. M. A., Romão, M. J., Carvalho, A. L., Fontes, C. M. G. A. & Romão, M. J. (2017). Journal of Biological Chemistry, 292(12), 4847-4860.
Deconstruction of cellulose, the most abundant plant cell wall polysaccharide, requires the cooperative activity of a large repertoire of microbial enzymes. Modular cellulases contain non-catalytic type A carbohydrate-binding modules (CBMs) that specifically bind to the crystalline regions of cellulose, thus promoting enzyme efficacy through proximity and targeting effects. Although type A CBMs play a critical role in cellulose recycling, their mechanism of action remains poorly understood. Here we produced a library of recombinant CBMs representative of the known diversity of type A modules. The binding properties of 40 CBMs, in fusion with an N-terminal GFP domain, revealed that type A CBMs possess the ability to recognize different crystalline forms of cellulose and chitin over a wide range of temperatures, pH levels, and ionic strengths. A Spirochaeta thermophila CBM64, in particular, displayed plasticity in its capacity to bind both crystalline and soluble carbohydrates under a wide range of extreme conditions. The structure of S. thermophila StCBM64C revealed an untwisted, flat, carbohydrate-binding interface comprising the side chains of four tryptophan residues in a co-planar linear arrangement. Significantly, two highly conserved asparagine side chains, each one located between two tryptophan residues, are critical to insoluble and soluble glucan recognition but not to bind xyloglucan. Thus, CBM64 compact structure and its extended and versatile ligand interacting platform illustrate how type A CBMs target their appended plant cell wall-degrading enzymes to a diversity of recalcitrant carbohydrates under a wide range of environmental conditions.
A novel method to quantify β-glucan in processed foods: Sodium hypochlorite Extracting and Enzymatic Digesting (SEED) assay.
Ide, M., Okumura, M., Koizumi, K., Kumagai, M., Yoshida, I., Yoshida, M., Mishima, T. & Nakamura, M. (2018). Journal of Agricultural and Food Chemistry, In Press.
Some β-glucans have attracted attention due to their functionality as an immunostimulant and have been used in processed foods. However, accurately measuring the β-glucan content of processed foods using existing methods is difficult. We demonstrate a new method, the Sodium hypochlorite Extracting and Enzymatic Digesting (SEED) assay, in which β-glucan is extracted using sodium hypochlorite, dimethyl sulfoxide, and 5 mol/L sodium hydroxide and then digested into β-glucan fragments using Westase which is an enzyme having β-1,6- and β-1,3 glucanase activity. The β-glucan fragments are further digested into glucose using exo-1,3-β-D-glucanase and β-glucosidase. We measured β-glucan comprising β-1,3-, -1,6-, and -1,(3),4- bonds in various polysaccharide reagents and processed foods using our novel method. The SEED assay was able to quantify β-glucan with good reproducibility, and the recovery rate was >90% for food containing β-glucan. Therefore, the SEED assay is capable of accurately measuring the β-glucan content of processed foods.
Functional characterization of a thermostable endoglucanase belonging to glycoside hydrolase family 45 from Fomitopsis palustris.
Cha, J. H., Yoon, J. J. & Cha, C. J. (2018). Applied Microbiology and Biotechnology, 102(15), 6515-6523.
A gene encoding an endoglucanase belonging to subfamily C of glycoside hydrolase family 45 (GH45) was identified in the brown rot fungus Fomitopsis palustris and functionally expressed in Pichia pastoris. The recombinant protein displayed hydrolytic activities toward various substrates such as carboxymethyl cellulose, phosphoric acid swollen cellulose, glucomannan, lichenan, and β-glucan. In particular, the enzyme had a unique catalytic efficiency on β-1,4-glucans rather than mixed β-1,3/1,4-glucans as compared to other GH45 endoglucanases. The fungal enzyme was relatively thermostable, retaining more than 91.4% activity at 80°C for 1 h. Site-directed mutagenesis studies revealed that the mutants N95D and D117N had significantly reduced enzymatic activities, indicating that both residues are essential for the catalytic reaction. Our study expands knowledge and understanding of the catalytic mechanism of GH45 subfamily C enzymes and also suggests that this thermostable endoglucanase from F. palustris has great potential in industrial applications.