scholarly journals Distinct roles of N- and O-glycans in cellulase activity and stability

2017 ◽  
Vol 114 (52) ◽  
pp. 13667-13672 ◽  
Author(s):  
Antonella Amore ◽  
Brandon C. Knott ◽  
Nitin T. Supekar ◽  
Asif Shajahan ◽  
Parastoo Azadi ◽  
...  
Keyword(s):  
Plant Cell Wall ◽  
Catalytic Domain ◽  
Domain Architecture ◽  
Cellulase Activity ◽  
Glycoside Hydrolases ◽  
Glycoside Hydrolase Family ◽  
Carbohydrate Binding ◽  
Cell Wall Degrading Enzymes ◽  
Cellulose Conversion ◽  
Degrading Enzymes

In nature, many microbes secrete mixtures of glycoside hydrolases, oxidoreductases, and accessory enzymes to deconstruct polysaccharides and lignin in plants. These enzymes are often decorated with N- and O-glycosylation, the roles of which have been broadly attributed to protection from proteolysis, as the extracellular milieu is an aggressive environment. Glycosylation has been shown to sometimes affect activity, but these effects are not fully understood. Here, we examine N- and O-glycosylation on a model, multimodular glycoside hydrolase family 7 cellobiohydrolase (Cel7A), which exhibits an O-glycosylated carbohydrate-binding module (CBM) and an O-glycosylated linker connected to an N- and O-glycosylated catalytic domain (CD)—a domain architecture common to many biomass-degrading enzymes. We report consensus maps for Cel7A glycosylation that include glycan sites and motifs. Additionally, we examine the roles of glycans on activity, substrate binding, and thermal and proteolytic stability. N-glycan knockouts on the CD demonstrate that N-glycosylation has little impact on cellulose conversion or binding, but does have major stability impacts. O-glycans on the CBM have little impact on binding, proteolysis, or activity in the whole-enzyme context. However, linker O-glycans greatly impact cellulose conversion via their contribution to proteolysis resistance. Molecular simulations predict an additional role for linker O-glycans, namely that they are responsible for maintaining separation between ordered domains when Cel7A is engaged on cellulose, as models predict α-helix formation and decreased cellulose interaction for the nonglycosylated linker. Overall, this study reveals key roles for N- and O-glycosylation that are likely broadly applicable to other plant cell-wall–degrading enzymes.

scholarly journals The modular architecture of Cellvibrio japonicus mannanases in glycoside hydrolase families 5 and 26 points to differences in their role in mannan degradation

2003 ◽  
Vol 371 (3) ◽  
pp. 1027-1043 ◽  
Author(s):  
Deborah HOGG ◽  
Gavin PELL ◽  
Paul DUPREE ◽  
Florence GOUBET ◽  
Susana M. MARTÍN-ORÚE ◽  
...  
Keyword(s):  
Glycoside Hydrolase ◽  
Plant Cell Wall ◽  
Catalytic Domain ◽  
Glycoside Hydrolases ◽  
Crystalline Cellulose ◽  
Carbohydrate Binding ◽  
Molecular Architecture ◽  
Catalytic Domains ◽  
Carbohydrate Binding Modules ◽  
Cellvibrio Japonicus

β-1,4-Mannanases (mannanases), which hydrolyse mannans and glucomannans, are located in glycoside hydrolase families (GHs) 5 and 26. To investigate whether there are fundamental differences in the molecular architecture and biochemical properties of GH5 and GH26 mannanases, four genes encoding these enzymes were isolated from Cellvibrio japonicus and the encoded glycoside hydrolases were characterized. The four genes, man5A, man5B, man5C and man26B, encode the mannanases Man5A, Man5B, Man5C and Man26B, respectively. Man26B consists of an N-terminal signal peptide linked via an extended serine-rich region to a GH26 catalytic domain. Man5A, Man5B and Man5C contain GH5 catalytic domains and non-catalytic carbohydrate-binding modules (CBMs) belonging to families 2a, 5 and 10; Man5C in addition contains a module defined as X4 of unknown function. The family 10 and 2a CBMs bound to crystalline cellulose and ivory nut crystalline mannan, displaying very similar properties to the corresponding family 10 and 2a CBMs from Cellvibrio cellulases and xylanases. CBM5 bound weakly to these crystalline polysaccharides. The catalytic domains of Man5A, Man5B and Man26B hydrolysed galactomannan and glucomannan, but displayed no activity against crystalline mannan or cellulosic substrates. Although Man5C was less active against glucomannan and galactomannan than the other mannanases, it did attack crystalline ivory nut mannan. All the enzymes exhibited classic endo-activity producing a mixture of oligosaccharides during the initial phase of the reaction, although their mode of action against manno-oligosaccharides and glucomannan indicated differences in the topology of the respective substrate-binding sites. This report points to a different role for GH5 and GH26 mannanases from C. japonicus. We propose that as the GH5 enzymes contain CBMs that bind crystalline polysaccharides, these enzymes are likely to target mannans that are integral to the plant cell wall, while GH26 mannanases, which lack CBMs and rapidly release mannose from polysaccharides and oligosaccharides, target the storage polysaccharide galactomannan and manno-oligosaccharides.

scholarly journals Crystal structure of GH43 exo-β-1,3-galactanase from the basidiomycete Phanerochaete chrysosporium provides insights into the mechanism of bypassing side chains

2020 ◽  
Author(s):  
Kaori Matsuyama ◽  
Naomi Kishine ◽  
Zui Fujimoto ◽  
Naoki Sunagawa ◽  
Toshihisa Kotake ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Phanerochaete Chrysosporium ◽  
Catalytic Domain ◽  
Interaction Mechanism ◽  
Binding Domain ◽  
Glycoside Hydrolases ◽  
Glycoside Hydrolase Family ◽  
Carbohydrate Binding ◽  
Side Chains ◽  
Ligand Interaction

AbstractArabinogalactan proteins (AGPs) are functional plant proteoglycans, but their functions are largely unexplored, mainly because of the complexity of the sugar moieties, which are generally analyzed with the aid of glycoside hydrolases. In this study, we solved the apo and liganded structures of exo-β-1,3-galactanase from the basidiomycete Phanerochaete chrysosporium (Pc1,3Gal43A), which specifically cleaves AGPs. It is composed of a glycoside hydrolase family 43 subfamily 24 (GH43_sub24) catalytic domain together with a carbohydrate-binding module family (CBM) 35 binding domain. GH43_sub24 lacks the catalytic base Asp that is conserved among other GH43 subfamilies. Crystal structure and kinetic analyses indicated that the tautomerized imidic acid function of Gln263 serves instead as the catalytic base residue. Pc1,3Gal43A has three subsites that continue from the bottom of the catalytic pocket to the solvent. Subsite -1 contains a space that can accommodate the C-6 methylol of Gal, enabling the enzyme to bypass the β-1,6-linked galactan side chains of AGPs. Furthermore, the galactan-binding domain in CBM35 has a different ligand interaction mechanism from other sugar-binding CBM35s. Some of the residues involved in ligand recognition differ from those of galactomannan-binding CBM35, including substitution of Trp for Gly, which affects pyranose stacking, and substitution of Asn for Asp in the lower part of the binding pocket. Pc1,3Gal43A WT and its mutants at residues involved in substrate recognition are expected to be useful tools for structural analysis of AGPs. Our findings should also be helpful in engineering designer enzymes for efficient utilization of various types of biomass.

scholarly journals Crystallization and preliminary crystallographic studies of a novel noncatalytic carbohydrate-binding module from theRuminococcus flavefacienscellulosome

2015 ◽  
Vol 71 (1) ◽  
pp. 45-48 ◽  
Author(s):  
Immacolata Venditto ◽  
Arun Goyal ◽  
Andrew Thompson ◽  
Luis M. A. Ferreira ◽  
Carlos M. G. A. Fontes ◽  
...  
Keyword(s):  
Cell Wall ◽  
Plant Cell ◽  
Plant Cell Wall ◽  
Catalytic Domain ◽  
Glycoside Hydrolase Family ◽  
Carbohydrate Binding ◽  
Cellulolytic Bacterium ◽  
Modular Architecture ◽  
Carbohydrate Binding Modules ◽  
Fundamental Biological Process

Microbial degradation of the plant cell wall is a fundamental biological process with considerable industrial importance. Hydrolysis of recalcitrant polysaccharides is orchestrated by a large repertoire of carbohydrate-active enzymes that display a modular architecture in which a catalytic domain is connectedvialinker sequences to one or more noncatalytic carbohydrate-binding modules (CBMs). CBMs direct the appended catalytic modules to their target substrates, thus potentiating catalysis. The genome of the most abundant ruminal cellulolytic bacterium,Ruminococcus flavefaciensstrain FD-1, provides an opportunity to discover novel cellulosomal proteins involved in plant cell-wall deconstruction. It encodes a modular protein comprising a glycoside hydrolase family 9 catalytic module (GH9) linked to two unclassified tandemly repeated CBMs (termed CBM-Rf6A and CBM-Rf6B) and a C-terminal dockerin. The novel CBM-Rf6A from this protein has been crystallized and data were processed for the native and a selenomethionine derivative to 1.75 and 1.5 Å resolution, respectively. The crystals belonged to orthorhombic and cubic space groups, respectively. The structure was solved by a single-wavelength anomalous dispersion experiment using theCCP4 program suite andSHELXC/D/E.

scholarly journals Crystallization and preliminary X-ray diffraction analysis of Xyn30D fromPaenibacillus barcinonensis

2014 ◽  
Vol 70 (7) ◽  
pp. 963-966 ◽  
Author(s):  
María Ángela Sainz-Polo ◽  
Susana Valeria Valenzuela ◽  
F. Javier Pastor ◽  
Julia Sanz-Aparicio
Keyword(s):  
Catalytic Domain ◽  
Domain Architecture ◽  
Glycoside Hydrolase Family ◽  
Carbohydrate Binding ◽  
X Ray Diffraction ◽  
Full Data ◽  
Data Set ◽  
X Ray ◽  
Hydrolysis Of ◽  
Hydrolase Family

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.

Characterisation and functional importance of β-1,4-endoglucanases from the potato rot nematode, Ditylenchus destructor

Nematology ◽  
2014 ◽  
Vol 16 (5) ◽  
pp. 505-517 ◽  
Author(s):  
Huan Peng ◽  
Deliang Peng ◽  
Haibo Long ◽  
Wenting He ◽  
Feng Qiao ◽  
...  
Keyword(s):  
Plant Cell Wall ◽  
Catalytic Domain ◽  
Cellulase Activity ◽  
Molecular Data ◽  
Parasitic Nematodes ◽  
Carbohydrate Binding ◽  
Average Decrease ◽  
Intron Structure ◽  
Ditylenchus Destructor

Plant-parasitic nematodes have developed a series of enzymes to degrade the rigid plant cell wall; β-1,4-endoglucanase is a very important component. Ditylenchus destructor is a migratory endoparasite for which few molecular data have been published. Two novel β-1,4-endoglucanases (Dd-eng-1a and Dd-eng-2) were cloned and characterised from D. destructor. The DD-ENG-1A putative protein consists of a signal peptide, a catalytic domain and a carbohydrate-binding module (CBM). By contrast, the CBM domain is absent from DD-ENG-2. The exon/intron structure and phylogenetic tree indicate that both cellulase genes could have evolved from common ancestral genes. Southern blotting confirmed that the β-1,4-endoglucanases were of nematode origin and a member of a small multi-gene family. In situ hybridisation localised the expression of Dd-eng-1a and Dd-eng-2 to the subventral pharyngeal glands. RT-PCR showed that both genes were expressed in the adult female and second-stage juvenile. The stylet secretions of D. destructor showed clear cellulase activity in carboxymethylcellulose (CMC) plate assay, and similar results were observed in total homogenates and DD-ENG-1A and DD-ENG-2 recombinant proteins. These results demonstrated that D. destructor can produce and secrete functional cellulases. Silencing the putative β-1,4-endoglucanases by double-stranded RNA (dsRNA) resulted in an average decrease in infection of 50%. Successful RNAi in vitro was demonstrated in this study, which confirmed that Dd-eng-1a and Dd-eng-2 play important roles in nematode parasitism.

scholarly journals Unique active-site and subsite features in the arabinogalactan-degrading GH43 exo-β-1,3-galactanase from Phanerochaete chrysosporium

2020 ◽  
Vol 295 (52) ◽  
pp. 18539-18552
Author(s):  
Kaori Matsuyama ◽  
Naomi Kishine ◽  
Zui Fujimoto ◽  
Naoki Sunagawa ◽  
Toshihisa Kotake ◽  
...  
Keyword(s):  
Phanerochaete Chrysosporium ◽  
Glycoside Hydrolase ◽  
Catalytic Domain ◽  
Interaction Mechanism ◽  
Binding Domain ◽  
Glycoside Hydrolases ◽  
Glycoside Hydrolase Family ◽  
Carbohydrate Binding ◽  
Side Chains ◽  
Ligand Interaction

Arabinogalactan proteins (AGPs) are plant proteoglycans with functions in growth and development. However, these functions are largely unexplored, mainly because of the complexity of the sugar moieties. These carbohydrate sequences are generally analyzed with the aid of glycoside hydrolases. The exo-β-1,3-galactanase is a glycoside hydrolase from the basidiomycete Phanerochaete chrysosporium (Pc1,3Gal43A), which specifically cleaves AGPs. However, its structure is not known in relation to its mechanism bypassing side chains. In this study, we solved the apo and liganded structures of Pc1,3Gal43A, which reveal a glycoside hydrolase family 43 subfamily 24 (GH43_sub24) catalytic domain together with a carbohydrate-binding module family 35 (CBM35) binding domain. GH43_sub24 is known to lack the catalytic base Asp conserved among other GH43 subfamilies. Our structure in combination with kinetic analyses reveals that the tautomerized imidic acid group of Gln263 serves as the catalytic base residue instead. Pc1,3Gal43A has three subsites that continue from the bottom of the catalytic pocket to the solvent. Subsite −1 contains a space that can accommodate the C-6 methylol of Gal, enabling the enzyme to bypass the β-1,6–linked galactan side chains of AGPs. Furthermore, the galactan-binding domain in CBM35 has a different ligand interaction mechanism from other sugar-binding CBM35s, including those that bind galactomannan. Specifically, we noted a Gly → Trp substitution, which affects pyranose stacking, and an Asp → Asn substitution in the binding pocket, which recognizes β-linked rather than α-linked Gal residues. These findings should facilitate further structural analysis of AGPs and may also be helpful in engineering designer enzymes for efficient biomass utilization.

scholarly journals Biochemical and Structural Characterizations of Two Dictyostelium Cellobiohydrolases from the Amoebozoa Kingdom Reveal a High Level of Conservation between Distant Phylogenetic Trees of Life

2016 ◽  
Vol 82 (11) ◽  
pp. 3395-3409 ◽  
Author(s):  
Sarah E. Hobdey ◽  
Brandon C. Knott ◽  
Majid Haddad Momeni ◽  
Larry E. Taylor ◽  
Anna S. Borisova ◽  
...  
Keyword(s):  
Active Site ◽  
Phylogenetic Trees ◽  
Plant Cell Wall ◽  
Catalytic Domain ◽  
Cellulolytic Enzymes ◽  
Glycoside Hydrolase Family ◽  
Carbohydrate Binding ◽  
Industrial Enzymes ◽  
Content Type ◽  
Social Amoeba

ABSTRACTGlycoside hydrolase family 7 (GH7) cellobiohydrolases (CBHs) are enzymes commonly employed in plant cell wall degradation across eukaryotic kingdoms of life, as they provide significant hydrolytic potential in cellulose turnover. To date, many fungal GH7 CBHs have been examined, yet many questions regarding structure-activity relationships in these important natural and commercial enzymes remain. Here, we present the crystal structures and a biochemical analysis of two GH7 CBHs from social amoeba:Dictyostelium discoideumCel7A (DdiCel7A) andDictyostelium purpureumCel7A (DpuCel7A).DdiCel7A andDpuCel7A natively consist of a catalytic domain and do not exhibit a carbohydrate-binding module (CBM). The structures ofDdiCel7A andDpuCel7A, resolved to 2.1 Å and 2.7 Å, respectively, are homologous to those of other GH7 CBHs with an enclosed active-site tunnel. Two primary differences between theDictyosteliumCBHs and the archetypal model GH7 CBH,Trichoderma reeseiCel7A (TreCel7A), occur near the hydrolytic active site and the product-binding sites. To compare the activities of these enzymes with the activity ofTreCel7A, the family 1TreCel7A CBM and linker were added to the C terminus of each of theDictyosteliumenzymes, creatingDdiCel7ACBMandDpuCel7ACBM, which were recombinantly expressed inT. reesei.DdiCel7ACBMandDpuCel7ACBMhydrolyzed Avicel, pretreated corn stover, and phosphoric acid-swollen cellulose as efficiently asTreCel7A when hydrolysis was compared at their temperature optima. TheKiof cellobiose was significantly higher forDdiCel7ACBMandDpuCel7ACBMthan forTreCel7A: 205, 130, and 29 μM, respectively. Taken together, the present study highlights the remarkable degree of conservation of the activity of these key natural and industrial enzymes across quite distant phylogenetic trees of life.IMPORTANCEGH7 CBHs are among the most important cellulolytic enzymes both in nature and for emerging industrial applications for cellulose breakdown. Understanding the diversity of these key industrial enzymes is critical to engineering them for higher levels of activity and greater stability. The present work demonstrates that two GH7 CBHs from social amoeba are surprisingly quite similar in structure and activity to the canonical GH7 CBH from the model biomass-degrading fungusT. reeseiwhen tested under equivalent conditions (with added CBM-linker domains) on an industrially relevant substrate.

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 ◽  
...  
Keyword(s):  
Marine Bacteria ◽  
Glycoside Hydrolase ◽  
Catalytic Domain ◽  
Domain Architecture ◽  
Glycoside Hydrolase Family ◽  
Carbohydrate Binding ◽  
Carbohydrate Binding Module ◽  
Binding Ability ◽  
Content Type ◽  
Hydrolase Family

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.

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