Molecular arrangements that accompany binding of rice xylanase inhibitor protein OsXIP and the Rhizopus oryzae GH11 xylanase RXyn2.

Plants have evolved xylanase inhibitor proteins as part of their defense mechanisms against phytopathogens. The rice xylanase inhibitor protein (OsXIP) is structurally similar to GH18 chitinase and homologous to wheat XIP-type inhibitor (XIP-I), which inhibits both GH10 and GH11 xylanases. Various inhibition and interaction analyses showed that OsXIP competitively inhibits the hydrolytic activity of GH11 xylanase RXyn2, but not the activity of GH10 xylanase RXyn1 from Rhizopus oryzae.

Chitin recognition by a periplasmic chitooligosaccharide-binding protein from Vibrio cholerae.

The mechanism of chitin recognition by a periplasmic chitooligosaccharide-binding protein from Vibrio cholerae (VcCBP) was studied by thermal shift assays and isothermal titration calorimetry using di-N-acetylchitobiose, (GlcNAc)2; mono-N-acetylchitobioses, GlcN-GlcNAc and GlcNAc-GlcN; and fully de-N-acetylated chitobiose, (GlcN)2; as the ligands. As judged from the thermal shifts (ΔTm) of VcCBP upon the addition of individual chitobioses, the binding abilities toward VcCBP appeared to decrease in the order of (GlcNAc)2 > GlcN-GlcNAc > GlcNAc-GlcN ≫ (GlcN)2. Although the de-N-acetylation effect of the reducing end GlcNAc was more significant than that of the non-reducing end, both N-acetyl groups were found to cooperatively contribute to the interaction between VcCBP and (GlcNAc)2.

β1,6-Selective Enzymatic N-Acetylglucosamination Catalyzed by the Family GH84 N-Acetyl-β-D-glucosaminidase from Bacteroides thetaiotaomicron and its Glycosyl Acceptor Specificity.

The chemoenzymatic synthesis of oligosaccharides presents a highly attractive methodology with significant potential for diverse applications, particularly through using various glycosidases. In this study, the O-glycan core 6 disaccharide moiety, GlcNAcβ1-6GalNAc, was successfully synthesized via enzymatic glycosylation using an N-acetyl-β-D-glucosaminidase from Bacteroides thetaiotaomicron (BtOGA), a member of glycoside hydrolase family 84 (GH84), alongside an N-acetyl-D-glucosamine oxazoline derivative (GlcNAc-oxa) as the glycosyl donor. Furthermore, an investigation into glycosyl acceptor recognition in BtOGA-catalyzed enzymatic glycosylation indicated that the presence of an aromatic group at the anomeric position and an axial hydroxy group at the 4-position of the saccharide moiety is crucial for effective recognition of BtOGA as a glycosyl acceptor.

Periplasmic chitooligosaccharide-binding protein requires a three-domain organization for substrate translocation.

Periplasmic solute-binding proteins (SBPs) specific for chitooligosaccharides, (GlcNAc) (n = 2, 3, 4, 5 and 6), are involved in the uptake of chitinous nutrients and the negative control of chitin signal transduction in Vibrios. Most translocation processes by SBPs across the inner membrane have been explained thus far by two-domain open/closed mechanism. Here we propose three-domain mechanism of the (GlcNAc) translocation based on experiments using a recombinant VcCBP, SBP specific for (GlcNAc) from Vibrio cholerae.

The first report of enzymatic transglycosylation catalyzed by family GH84 N-acetyl-β-d-glucosaminidase using a sugar oxazoline derivative as a glycosyl donor.

O-Glycosylated N-acetyl-β-d-glucosamine-selective N-acetyl-β-d-glucosaminidase (O-GlcNAcase), belonging to glycoside hydrolase family 84 (GH84), is known as a retaining glycosidase with the possibility of enzymatic transglycosylation. However, no enzymatic transglycosylation catalyzed by GH84 O-GlcNAcase has been reported. Here, enzymatic transglycosylation catalyzed by GH84 O-GlcNAcase was first reported.

Characterization of two rice GH18 chitinases belonging to family 8 of plant pathogenesis-related proteins.

Two rice GH18 chitinases, Oschib1 and Oschib2, belonging to family 8 of plant pathogenesis-related proteins (PR proteins) were expressed, purified, and characterized. These enzymes, which have the structural features of class IIIb chitinases, preferentially cleaved the second glycosidic linkage from the non-reducing end of substrate chitin oligosaccharides as opposed to rice class IIIa enzymes, OsChib3a and OsChib3b, which mainly cleaved the fourth linkage from the non-reducing end of chitin hexasaccharide [(GlcNAc)]. Oschib1 and Oschiab2 inhibited the growth of Fusarium solani, but showed only a weak or no antifungal activity against Aspergillus niger and Trichoderma viride on the agar plates.

Plant Chitinase Mutants as the Catalysts for Chitooligosaccharide Synthesis Using the Sugar Oxazoline Derivatives.

Sugar oxazolines, (GlcNAc)-oxa ( = 2, 3, 4, and 5), were synthesized from a mixture of chitooligosaccharides, (GlcNAc) ( = 2, 3, 4, and 5), and utilized for synthesis of (GlcNAc) with higher elicitor activity using plant chitinase mutants as the catalysts. From isothermal titration calorimetry, the binding affinity of (GlcNAc)-oxa toward an inactive mutant obtained from GH18 chitinase was found to be higher than those of the other (GlcNAc)-oxa ( = 3, 4, and 5). To synthesize (GlcNAc), the donor/acceptor substrates with different size combinations, (GlcNAc)-oxa/(GlcNAc) (1), (GlcNAc)-oxa/(GlcNAc) (2), (GlcNAc)-oxa/(GlcNAc) (3), and (GlcNAc)-oxa/(GlcNAc) (4), were incubated with hypertransglycosylating mutants of GH18 chitinases from and .

Structure, mechanism, and phylogeny of LysM-chitinase conjugates specifically found in fern plants.

A unique GH18 chitinase containing two N-terminal lysin motifs (PrLysM1 and PrLysM2) was first found in fern, Pteris ryukyuensis (Onaga and Taira, Glycobiology, 18, 414-423, 2008). This type of LysM-chitinase conjugates is not usually found in plants but in fungi. Here, we produced a similar GH18 chitinase with one N-terminal LysM module (EaLysM) from the fern, Equisetum arvense (EaChiA, Inamine et al.

A conserved loop structure of GH19 chitinases assists the enzyme function from behind the core-functional region.

Plant GH19 chitinases have several loop structures, which may define their enzymatic properties. Among these loops, the longest loop, Loop-III, is most frequently conserved in GH19 enzymes. A GH19 chitinase from the moss Bryum coronatum (BcChi-A) has only one loop structure, Loop-III, which is connected to the catalytically important β-sheet region.

Thermodynamic Analysis for Binding of 4--β-tri--acetylchitotriosyl Moranoline, a Transition State Analogue Inhibitor for Hen Egg White Lysozyme.

4---tri--acetylchitotriosyl moranoline (GNM) is a transition-state analogue for hen egg white lysozyme (HEWL) and identified as the most potent inhibitor till date. Isothermal titration calorimetry experiments provided the thermodynamic parameters for binding of GNM to HEWL and revealed that the binding is driven by a favorable enthalpy change (Δ° = -11.0 kcal/mol) with an entropic penalty (-Δ° = 2.

Chemo-enzymatic synthesis of Lacto-N-biose I catalyzed by β-1,3-galactosidase from Bacillus circulans using 4,6-dimethoxy-1,3,5-triazin-2-yl β-galactopyranoside as a glycosyl donor.

Chemo-enzymatic synthesis of lacto-N-biose I (LNB) catalyzed by β-1,3-galactosidase from Bacillus circulans (BgaC) has been developed using 4,6-dimethoxy-1,3,5-triazin-2-yl β-galactopyranoside (DMT-β-Gal) and GlcNAc as the donor and acceptor substrates, respectively. BgaC transferred the Gal moiety to the acceptor, giving rise to LNB. The maximum yield of LNB was obtained at the acceptor : donor substrate ratio of 1:30.

Multi-functionality of a tryptophan residue conserved in substrate-binding groove of GH19 chitinases.

GH19 and GH22 glycoside hydrolases belonging to the lysozyme superfamily have a related structure/function. A highly conserved tryptophan residue, Trp103, located in the binding groove of a GH19 chitinase from moss Bryum coronatum (BcChi-A) appears to have a function similar to that of well-known Trp62 in GH22 lysozymes. Here, we found that mutation of Trp103 to phenylalanine (W103F) or alanine (W103A) strongly reduced the enzymatic activity of BcChi-A.

Kinetic and thermodynamic insights into the inhibitory mechanism of TMG-chitotriomycin on Vibrio campbellii GH20 exo-β-N-acetylglucosaminidase.

We investigated the inhibition kinetics of VhGlcNAcase, a GH20 exo-β-N-acetylglucosaminidase (GlcNAcase) from the marine bacterium Vibrio campbellii (formerly V. harveyi) ATCC BAA-1116, using TMG-chitotriomycin, a natural enzyme inhibitor specific for GH20 GlcNAcases from chitin-processing organisms, with p-nitrophenyl N-acetyl-β-d-glucosaminide (pNP-GlcNAc) as the substrate. TMG-chitotriomycin inhibited VhGlcNAcase with an IC of 3.

Crystal structure and biochemical characterization of CJP38, a β-1,3-glucanase and allergen of Cryptomeria japonica pollen.

A 38 kDa β-1,3-glucanase allergen from Cryptomeria japonica pollen (CJP38) was recombinantly produced in E. coli and purified to homogeneity with the use of Ni-affinity resin. CJP38 hydrolyzed β-1,3-glucans such as CM-curdlan and laminarioligosaccharides in an endo-splitting manner.

Characterization of a GH Family 20 Exo-β--acetylhexosaminidase with Antifungal Activity from .

We characterized HEX, which is a glycoside hydrolase (GH) family 20 exo-β--acetylhexosaminidase found in . HEX exolytically hydrolyzed chitin oligosaccharides from their non-reducing ends, and yielded -acetylglucosamine (GlcNAc) as the end product. According to the initial rate of substrate hydrolysis, the rates of (GlcNAc) and (GlcNAc) hydrolysis were greater than the rates for the other oligosaccharides.

Structures and chitin-binding properties of two N-terminal lysin motifs (LysMs) found in a chitinase from Volvox carteri.

Two N-terminal lysin motifs (LysMs) found in a chitinase from the green alga Volvox carteri (VcLysM1 and VcLysM2) were produced, and their structures and chitin-binding properties were characterized. The binding affinities of VcLysM1 toward chitin oligomers determined by isothermal titration calorimetry (ITC) were higher than those of VcLysM2 by 0.8-1.

A novel method for chemo-enzymatic synthesis of chitin oligosaccharide catalyzed by the mutant of inverting family GH19 chitinase using 4,6-dimethoxy-1,3,5-triazin-2-yl α-chitobioside as a glycosyl donor.

A novel method for the chemo-enzymatic synthesis of chitin oligosaccharide catalyzed by mutants of BcChi-A, an inverting family GH19 chitinase from Bryum coronatum, has been developed using 4,6-dimethoxy-1,3,5-triazin-2-yl α-chitobioside [DMT-α-(GlcNAc)2)] as a donor substrate. Based on the glycosynthase derived from BcChi-A, Glu70, which acts as a catalytic base, and Ser102, which fixes a nucleophilic water molecule, were changed to generate several single and double mutants of BcChi-A, which were employed in synthetic reactions. Among the double mutants tested, E70G/S102G, E70G/S102C and E70G/S102A were found to successfully synthesize chitotetraose [(GlcNAc)4] from DMT-α-(GlcNAc)2 and (GlcNAc)2; however, the single mutants, E70G, S102G, S102C and S102A, did not.

NgcE Acts as a Lower-Affinity Binding Protein of an ABC Transporter for the Uptake of N,N'-Diacetylchitobiose in Streptomyces coelicolor A3(2).

In the model species Streptomyces coelicolor A3(2), the uptake of chitin-degradation byproducts, mainly N,N'- diacetylchitobiose ([GlcNAc]) and N-acetylglucosamine (GlcNAc), is performed by the ATP-binding cassette (ABC) transporter DasABC-MsiK and the sugar-phosphotransferase system (PTS), respectively. Studies on the S. coelicolor chromosome have suggested the occurrence of additional uptake systems of GlcNAc-related compounds, including the SCO6005-7 cluster, which is orthologous to the ABC transporter NgcEFG of S.

Mode of action and specificity of a chitinase from unicellular microalgae, Euglena gracilis.

Euglena gracilis is a unicellular microalga showing characteristics of both plants and animals, and extensively used as a model organism in the research works of biochemistry and molecular biology. Biotechnological applications of E. gracilis have been conducted for production of numerous important compounds.

Structure and Enzymatic Properties of a Two-Domain Family GH19 Chitinase from Japanese Cedar ( Cryptomeria japonica) Pollen.

CJP-4 is an allergen found in pollen of the Japanese cedar Cryptomeria japonica. The protein is a two-domain family GH19 (class IV) Chitinase consisting of an N-terminal CBM18 domain and a GH19 catalytic domain. Here, we produced recombinant CJP-4 and CBM18-truncated CJP-4 (CJP-4-Cat) proteins.

Unique GH18 chitinase from Euglena gracilis: full-length cDNA cloning and characterization of its catalytic domain.

A cDNA of putative chitinase from Euglena gracilis, designated EgChiA, encoded 960 amino acid residues, which is arranged from N-terminus in the order of signal peptide, glycoside hydrolase family 18 (GH18) domain, carbohydrate binding module family 18 (CBM18) domain, GH18 domain, CBM18 domain, and transmembrane helix. It is likely that EgChiA is anchored on the cell surface. The recombinant second GH18 domain of EgChiA, designated as CatD2, displayed optimal catalytic activity at pH 3.

NMR analysis of substrate binding to a two-domain chitinase: Comparison between soluble and insoluble chitins.

CJP-4 is a two-domain chitinase from Japanese cedar (Cryptomeria japonica) pollen, consisting of an N-terminal CBM18 domain and a GH19 catalytic domain. The substrate binding to an inactive mutant protein of full-length CJP-4, in which the catalytic acid Glu108 was mutated to glutamine, CJP-4(E108Q), was analyzed by NMR spectroscopy. Based on the chemical shift perturbations of H-N HSQC signals of Gly26 (CBM18 domain) and Trp185 (GH19 domain), the association constants for individual domains of CJP-4(E108Q) toward soluble chitin hexamer (GlcNAc) were determined to be 2300 and 3500 M, respectively.

Crystal structure and thermodynamic dissection of chitin oligosaccharide binding to the LysM module of chitinase-A from Pteris ryukyuensis.

We determined the crystal structure of a LysM module from Pteris ryukyuensis chitinase-A (PrLysM2) at a resolution of 1.8 Å. Structural and binding analysis of PrLysM2 indicated that this module recognizes chitin oligosaccharides in a shallow groove comprised of five sugar-binding subsites on one side of the molecule.

Insertion of a Loop Structure into the "Loopless" GH19 Chitinase from .

Chitinases belonging to the GH19 family have diverse loop structure arrangements. A GH19 chitinase from rye seeds (RSC-c) has a full set of (six) loop structures that form an extended binding cleft from -4 to +4 ("loopful"), while that from moss (BcChi-A) lacks several loops and forms a shortened binding cleft from -2 to +2 ("loopless"). We herein inserted a loop involved in sugar residue binding at subsites +3 and +4 of RSC-c (Loop-II) into BcChi-A (BcChi-A+L-II), and the thermal stability and enzymatic activity of BcChi-A+L-II were then characterized and compared with those of BcChi-A.

Enzymatic properties of a GH19 chitinase isolated from rice lacking a major loop structure involved in chitin binding.

The catalytic domains of family GH19 chitinases have been found to consist of a conserved, α-helical core-region and different numbers (1-6) of loop structures, located at both ends of the substrate-binding groove and which extend over the glycon- and aglycon-binding sites. We expressed, purified and enzymatically characterized a GH19 chitinase from rice, Oryza sativa L. cv.