scholarly journals A New Group of Modular Xylanases in Glycoside Hydrolase Family 8 from Marine Bacteria

2018 ◽  
Vol 84 (23) ◽  
Author(s):  
Xiu-Lan Chen ◽  
Fang Zhao ◽  
Yong-Sheng Yue ◽  
Xi-Ying Zhang ◽  
Yu-Zhong Zhang ◽  
...  

ABSTRACT Xylanases play a crucial role in the degradation of xylan in both terrestrial and marine environments. The endoxylanase XynB from the marine bacterium Glaciecola mesophila KMM 241 is a modular enzyme comprising a long N-terminal domain (NTD) (E44 to T562) with xylan-binding ability and a catalytic domain (CD) (T563 to E912) of glycoside hydrolase family 8 (GH8). In this study, the long NTD is confirmed to contain three different functional regions, which are NTD1 (E44 to D136), NTD2 (Y137 to A193), and NTD3 (L194 to T562). NTD1, mainly composed of eight β-strands, functions as a new type of carbohydrate-binding module (CBM), which has xylan-binding ability but no sequence similarity to any known CBM. NTD2, mainly forming two α-helices, contains one of the α-helices of the catalytic domain's (α/α)6 barrel and therefore is essential for the activity of XynB, although it is far away from the catalytic domain in sequence. NTD3, next to the catalytic domain in sequence, is shown to be helpful in maintaining the thermostability of XynB. Thus, XynB represents a kind of xylanase with a new domain architecture. There are four other predicted glycoside hydrolase sequences with the same domain architecture and high sequence identity (≥80%) with XynB, all of which are from marine bacteria. Phylogenetic analysis shows that XynB and these homologs form a new group in GH8, representing a new class of marine bacterial xylanases. Our results shed light on xylanases, especially marine xylanases. IMPORTANCE Xylanases play a crucial role in natural xylan degradation and have been extensively used in industries such as food processing, animal feed, and kraft pulp biobleaching. Some marine bacteria have been found to secrete xylanases. Characterization of novel xylanases from marine bacteria has significance for both the clarification of xylan degradation mechanisms in the sea and the development of new enzymes for industrial application. With G. mesophila XynB as a representative, this study reveals a new group of the GH8 xylanases from marine bacteria, which have a distinct domain architecture and contain a novel carbohydrate-binding module. Thus, this study offers new knowledge on marine xylanases.


2009 ◽  
Vol 418 (1) ◽  
pp. 39-47 ◽  
Author(s):  
Elien Vandermarliere ◽  
Tine M. Bourgois ◽  
Martyn D. Winn ◽  
Steven van Campenhout ◽  
Guido Volckaert ◽  
...  

AXHs (arabinoxylan arabinofuranohydrolases) are α-L-arabinofuranosidases that specifically hydrolyse the glycosidic bond between arabinofuranosyl substituents and xylopyranosyl backbone residues of arabinoxylan. Bacillus subtilis was recently shown to produce an AXH that cleaves arabinose units from O-2- or O-3-mono-substituted xylose residues: BsAXH-m2,3 (B. subtilis AXH-m2,3). Crystallographic analysis reveals a two-domain structure for this enzyme: a catalytic domain displaying a five-bladed β-propeller fold characteristic of GH (glycoside hydrolase) family 43 and a CBM (carbohydrate-binding module) with a β-sandwich fold belonging to CBM family 6. Binding of substrate to BsAXH-m2,3 is largely based on hydrophobic stacking interactions, which probably allow the positional flexibility needed to hydrolyse both arabinose substituents at the O-2 or O-3 position of the xylose unit. Superposition of the BsAXH-m2,3 structure with known structures of the GH family 43 exo-acting enzymes, β-xylosidase and α-L-arabinanase, each in complex with their substrate, reveals a different orientation of the sugar backbone.



2012 ◽  
Vol 79 (3) ◽  
pp. 989-996 ◽  
Author(s):  
Fei Zheng ◽  
Shaojun Ding

ABSTRACTEG1 is a modular glycoside hydrolase family 5 endoglucanase fromVolvariella volvaceaconsisting of an N-terminal carbohydrate-binding module (CBM1) and a catalytic domain (CD). The ratios of soluble to insoluble reducing sugar produced from filter paper after 8 and 24 h of exposure to EG1 were 6.66 and 8.56, respectively, suggesting that it is a processive endoglucanase. Three derivatives of EG1 containing a core domain only or additional CBMs were constructed in order to evaluate the contribution of the CBM to the processivity and enzymatic mode of EG1 under stationary and agitated conditions. All four enzymatic forms exhibited the same mode of action on both soluble and insoluble cellulosic substrates with cellobiose as a main end product. An additional CBM fused at either the N or C terminus reduced specific activity toward soluble and insoluble celluloses under stationary reaction conditions. Deletion of the CBM significantly decreased enzyme processivity. Insertion of an additional CBM also resulted in a dramatic decrease in processivity in enzyme-substrate reaction mixtures incubated for 0.5 h, but this effect was reversed when reactions were allowed to proceed for longer periods (24 h). Further significant differences were observed in the substrate adsorption/desorption patterns of EG1 and enzyme derivatives equipped with an additional CBM under agitated reaction conditions. An additional family 1 CBM improved EG1 processivity on insoluble cellulose under highly agitated conditions. Our data indicate a strong link between high adsorption levels and low desorption levels in the processivity of EG1 and possibly other processive endoglucanses.



Author(s):  
María Ángela Sainz-Polo ◽  
Susana Valeria Valenzuela ◽  
F. Javier Pastor ◽  
Julia Sanz-Aparicio

Xyn30D, a new member of a recently identified group of xylanases, has been purified and crystallized. Xyn30D is a bimodular enzyme composed of an N-terminal catalytic domain belonging to glycoside hydrolase family 30 (GH30) and a C-terminal family 35 carbohydrate-binding domain (CBM35) able to bind xylans and glucuronic acid. Xyn30D shares the characteristic endo mode of action described for GH30 xylanases, with the hydrolysis of the β-(1,4) bonds of xylan being directed by α-1,2-linked glucuronate moieties, which have to be placed at the −2 subsite of the xylanase active site. Crystals of the complete enzyme were obtained and a full data set to 2.3 Å resolution was collected using a synchrotron X-ray source. This represents the first bimodular enzyme with the domain architecture GH30-CBM35. This study will contribute to the understanding of the role that the different xylanases play in the depolymerization of glucuronoxylan.





2016 ◽  
Vol 291 (14) ◽  
pp. 7527-7540 ◽  
Author(s):  
Yoann Brison ◽  
Yannick Malbert ◽  
Georges Czaplicki ◽  
Lionel Mourey ◽  
Magali Remaud-Simeon ◽  
...  


2016 ◽  
Vol 82 (14) ◽  
pp. 4340-4349 ◽  
Author(s):  
Damao Wang ◽  
Do Hyoung Kim ◽  
Nari Seo ◽  
Eun Ju Yun ◽  
Hyun Joo An ◽  
...  

ABSTRACTIn this study, we characterized Gly5M, originating from a marine bacterium, as a novel β-1,3-1,6-endoglucanase in glycoside hydrolase family 5 (GH5) in the Carbohydrate-Active enZyme database. Thegly5Mgene encodes Gly5M, a newly characterized enzyme from GH5 subfamily 47 (GH5_47) inSaccharophagus degradans2-40T. Thegly5Mgene was cloned and overexpressed inEscherichia coli. Through analysis of the enzymatic reaction products by thin-layer chromatography, high-performance liquid chromatography, and matrix-assisted laser desorption ionization–tandem time of flight mass spectrometry, Gly5M was identified as a novel β-1,3-endoglucanase (EC 3.2.1.39) and bacterial β-1,6-glucanase (EC 3.2.1.75) in GH5. The β-1,3-endoglucanase and β-1,6-endoglucanase activities were detected by using laminarin (a β-1,3-glucan with β-1,6-glycosidic linkages derived from brown macroalgae) and pustulan (a β-1,6-glucan derived from fungal cell walls) as the substrates, respectively. This enzyme also showed transglycosylase activity toward β-1,3-oligosaccharides when laminarioligosaccharides were used as the substrates. Since laminarin is the major form of glucan storage in brown macroalgae, Gly5M could be used to produce glucose and laminarioligosaccharides, using brown macroalgae, for industrial purposes.IMPORTANCEIn this study, we have discovered a novel β-1,3-1,6-endoglucanase with a unique transglycosylase activity, namely, Gly5M, from a marine bacterium,Saccharophagus degradans2-40T. Gly5M was identified as the newly found β-1,3-endoglucanase and bacterial β-1,6-glucanase in GH5. Gly5M is capable of cleaving glycosidic linkages of both β-1,3-glucans and β-1,6-glucans. Gly5M also possesses a transglycosylase activity toward β-1,3-oligosacchrides. Due to the broad specificity of Gly5M, this enzyme can be used to produce glucose or high-value β-1,3- and/or β-1,6-oligosaccharides.



2020 ◽  
Vol 6 (10) ◽  
Author(s):  
Ao Li ◽  
Elisabeth Laville ◽  
Laurence Tarquis ◽  
Vincent Lombard ◽  
David Ropartz ◽  
...  

Mannoside phosphorylases are involved in the intracellular metabolization of mannooligosaccharides, and are also useful enzymes for the in vitro synthesis of oligosaccharides. They are found in glycoside hydrolase family GH130. Here we report on an analysis of 6308 GH130 sequences, including 4714 from the human, bovine, porcine and murine microbiomes. Using sequence similarity networks, we divided the diversity of sequences into 15 mostly isofunctional meta-nodes; of these, 9 contained no experimentally characterized member. By examining the multiple sequence alignments in each meta-node, we predicted the determinants of the phosphorolytic mechanism and linkage specificity. We thus hypothesized that eight uncharacterized meta-nodes would be phosphorylases. These sequences are characterized by the absence of signal peptides and of the catalytic base. Those sequences with the conserved E/K, E/R and Y/R pairs of residues involved in substrate binding would target β-1,2-, β-1,3- and β-1,4-linked mannosyl residues, respectively. These predictions were tested by characterizing members of three of the uncharacterized meta-nodes from gut bacteria. We discovered the first known β-1,4-mannosyl-glucuronic acid phosphorylase, which targets a motif of the Shigella lipopolysaccharide O-antigen. This work uncovers a reliable strategy for the discovery of novel mannoside-phosphorylases, reveals possible interactions between gut bacteria, and identifies a biotechnological tool for the synthesis of antigenic oligosaccharides.



2019 ◽  
Vol 201 (23) ◽  
Author(s):  
Bal Krishnan ◽  
Shanti Swaroop Srivastava ◽  
Venu Sankeshi ◽  
Rupsi Garg ◽  
Sudhakar Srivastava ◽  
...  

ABSTRACT The prokaryotic βγ-crystallins are a large group of uncharacterized domains with Ca2+-binding motifs. We have observed that a vast number of these domains are found appended to other domains, in particular, the carbohydrate-active enzyme (CAZy) domains. To elucidate the functional significance of these prospective Ca2+ sensors in bacteria and this widespread domain association, we have studied one typical example from Clostridium beijerinckii, a bacterium known for its ability to produce acetone, butanol, and ethanol through fermentation of several carbohydrates. This novel glycoside hydrolase of family 64 (GH64), which we named glucanallin, is composed of a βγ-crystallin domain, a GH64 domain, and a carbohydrate-binding module 56 (CBM56). The substrates of GH64, β-1,3-glucans, are the targets for industrial biofuel production due to their plenitude. We have examined the Ca2+-binding properties of this protein, assayed its enzymatic activity, and analyzed the structural features of the β-1,3-glucanase domain through its high-resolution crystal structure. The reaction products resulting from the enzyme reaction of glucanallin reinforce the mixed nature of GH64 enzymes, in contrast to the prevailing notion of them being an exotype. Upon disabling Ca2+ binding and comparing different domain combinations, we demonstrate that the βγ-crystallin domain in glucanallin acts as a Ca2+ sensor and enhances the glycolytic activity of glucanallin through Ca2+ binding. We also compare the structural peculiarities of this new member of the GH64 family to two previously studied members. IMPORTANCE We have biochemically and structurally characterized a novel glucanase from the less studied GH64 family in a bacterium significant for fermentation of carbohydrates into biofuels. This enzyme displays a peculiar property of being distally modulated by Ca2+ via assistance from a neighboring βγ-crystallin domain, likely through changes in the domain interface. In addition, this enzyme is found to be optimized for functioning in an acidic environment, which is in line with the possibility of its involvement in biofuel production. Multiple occurrences of a similar domain architecture suggest that such a “βγ-crystallination”-mediated Ca2+ sensitivity may be widespread among bacterial proteins.



2005 ◽  
Vol 71 (12) ◽  
pp. 7670-7678 ◽  
Author(s):  
Katsuro Yaoi ◽  
Tomonori Nakai ◽  
Yoshiro Kameda ◽  
Ayako Hiyoshi ◽  
Yasushi Mitsuishi

ABSTRACT Two xyloglucan-specific endo-β-1,4-glucanases (xyloglucanases [XEGs]), XEG5 and XEG74, with molecular masses of 40 kDa and 105 kDa, respectively, were isolated from the gram-positive bacterium Paenibacillus sp. strain KM21, which degrades tamarind seed xyloglucan. The genes encoding these XEGs were cloned and sequenced. Based on their amino acid sequences, the catalytic domains of XEG5 and XEG74 were classified in the glycoside hydrolase families 5 and 74, respectively. XEG5 is the first xyloglucanase belonging to glycoside hydrolase family 5. XEG5 lacks a carbohydrate-binding module, while XEG74 has an X2 module and a family 3 type carbohydrate-binding module at its C terminus. The two XEGs were expressed in Escherichia coli, and recombinant forms of the enzymes were purified and characterized. Both XEGs had endoglucanase active only toward xyloglucan and not toward Avicel, carboxymethylcellulose, barley β-1,3/1,4-glucan, or xylan. XEG5 is a typical endo-type enzyme that randomly cleaves the xyloglucan main chain, while XEG74 has dual endo- and exo-mode activities or processive endo-mode activity. XEG5 digested the xyloglucan oligosaccharide XXXGXXXG to produce XXXG, whereas XEG74 digestion of XXXGXXXG resulted in XXX, XXXG, and GXXXG, suggesting that this enzyme cleaves the glycosidic bond of unbranched Glc residues. Analyses using various oligosaccharide structures revealed that unique structures of xyloglucan oligosaccharides can be prepared with XEG74.



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