scholarly journals Glycoside Hydrolase Genes Are Required for Virulence ofAgrobacterium tumefaciensonBryophyllum daigremontianaand Tomato

2019 ◽  
Vol 85 (15) ◽  
Author(s):  
Stephanie L. Mathews ◽  
Haylea Hannah ◽  
Hillary Samagaio ◽  
Camille Martin ◽  
Eleanor Rodriguez-Rassi ◽  
...  
Keyword(s):  
Cell Wall ◽  
Host Cell ◽  
Plant Cell ◽  
Crown Gall ◽  
Plant Cell Wall ◽  
Tumor Formation ◽  
Glycoside Hydrolases ◽  
Plant Host ◽  
Content Type ◽  
Limited Digestion

ABSTRACTAgrobacterium tumefaciensis a rhizosphere bacterium that can infect wound sites on plants. The bacterium transfers a segment of DNA (T-DNA) from the Ti plasmid to the plant host cell via a type IV secretion system where the DNA becomes integrated into the host cell chromosomes. The expression of T-DNA in the plant results in tumor formation. Although the binding of the bacteria to plant surfaces has been studied previously, there is little work on possible interactions of the bacteria with the plant cell wall. Seven of the 48 genes encoding putative glycoside hydrolases (Atu2295,Atu2371,Atu3104,Atu3129,Atu4560,Atu4561, andAtu4665) in the genome ofA. tumefaciensC58 were found to play a role in virulence on tomato andBryophyllum daigremontiana. Two of these genes (pglAandpglB;Atu3129andAtu4560) encode enzymes capable of digesting polygalacturonic acid and, thus, may play a role in the digestion of pectin. One gene (arfA;Atu3104) encodes an arabinosylfuranosidase, which could remove arabinose from the ends of polysaccharide chains. Two genes (bglAandbglB;Atu2295andAtu4561) encode proteins with β-glycosidase activity and could digest a variety of plant cell wall oligosaccharides and polysaccharides. One gene (xynA;Atu2371) encodes a putative xylanase, which may play a role in the digestion of xylan. Another gene (melA;Atu4665) encodes a protein with α-galactosidase activity and may be involved in the breakdown of arabinogalactans. Limited digestion of the plant cell wall byA. tumefaciensmay be involved in tumor formation on tomato andB. daigremontiana.IMPORTANCEA. tumefaciensis used in the construction of genetically engineered plants, as it is able to transfer DNA to plant hosts. Knowledge of the mechanisms of DNA transfer and the genes required will aid in the understanding of this process. Manipulation of glycoside hydrolases may increase transformation and widen the host range of the bacterium.A. tumefaciensalso causes disease (crown gall tumors) on a variety of plants, including stone fruit trees, grapes, and grafted ornamentals such as roses. It is possible that compounds that inhibit glycoside hydrolases could be used to control crown gall disease caused byA. tumefaciens.

scholarly journals Metatranscriptomic Analyses of Plant Cell Wall Polysaccharide Degradation by Microorganisms in the Cow Rumen

2014 ◽  
Vol 81 (4) ◽  
pp. 1375-1386 ◽  
Author(s):  
Xin Dai ◽  
Yan Tian ◽  
Jinting Li ◽  
Xiaoyun Su ◽  
Xuewei Wang ◽  
...  
Keyword(s):  
Cell Wall ◽  
Plant Cell ◽  
Plant Cell Wall ◽  
Average Length ◽  
Glycoside Hydrolases ◽  
Carbohydrate Binding ◽  
Cell Wall Polysaccharide ◽  
Cell Wall Polysaccharides ◽  
Content Type ◽  
Carbohydrate Binding Modules

ABSTRACTThe bovine rumen represents a highly specialized bioreactor where plant cell wall polysaccharides (PCWPs) are efficiently deconstructed via numerous enzymes produced by resident microorganisms. Although a large number of fibrolytic genes from rumen microorganisms have been identified, it remains unclear how they are expressed in a coordinated manner to efficiently degrade PCWPs. In this study, we performed a metatranscriptomic analysis of the rumen microbiomes of adult Holstein cows fed a fiber diet and obtained a total of 1,107,083 high-quality non-rRNA reads with an average length of 483 nucleotides. Transcripts encoding glycoside hydrolases (GHs) and carbohydrate binding modules (CBMs) accounted for ∼1% and ∼0.1% of the total non-rRNAs, respectively. The majority (∼98%) of the putative cellulases belonged to four GH families (i.e., GH5, GH9, GH45, and GH48) and were primarily synthesized byRuminococcusandFibrobacter. Notably, transcripts for GH48 cellobiohydrolases were relatively abundant compared to the abundance of transcripts for other cellulases. Two-thirds of the putative hemicellulases were of the GH10, GH11, and GH26 types and were produced by members of the generaRuminococcus,Prevotella, andFibrobacter. Most (∼82%) predicted oligosaccharide-degrading enzymes were GH1, GH2, GH3, and GH43 proteins and were from a diverse group of microorganisms. Transcripts for CBM10 and dockerin, key components of the cellulosome, were also relatively abundant. Our results provide metatranscriptomic evidence in support of the notion that members of the generaRuminococcus,Fibrobacter, andPrevotellaare predominant PCWP degraders and point to the significant contribution of GH48 cellobiohydrolases and cellulosome-like structures to efficient PCWP degradation in the cow rumen.

scholarly journals Biological Function(s) and Application (s) of Pectin and Pectin Degrading Enzymes

2018 ◽  
Vol 15 (1) ◽  
pp. 87-100 ◽  
Author(s):  
Puja Chandrayan
Keyword(s):  
Cell Wall ◽  
Structure Function ◽  
Plant Cell ◽  
Plant Cell Wall ◽  
Plant Defence ◽  
Glycoside Hydrolases ◽  
Limited Information ◽  
Thermostable Enzymes ◽  
Network Cell ◽  
Degrading Enzymes

Pectin is an integral part of plant cell wall and since centuries pectin extracted from plants is widely used in food and fruit juice processing. Moreover, in last half century, the applications have also invaded into many bio-processing applications such as pharmaceutical, bioenergy, textile, paper and tea processing. In these growing industries, the use of pectinases has grown with a significant amount i.e. approximately 10 % of total global enzyme market comes from pectinases. Herein comprehensive analyses of information related to structure and function of pectin in plant cell wall as well as structural classes of pectins have been discussed. The major function of pectin is in cementing the cellulose and hemicelluloses network, cell-cell adhesion and plant defence. Keeping the wide use of pectin in food industry and growing need of environment friendly technology for pectin extraction has accelerated the demand of pectin degrading enzymes (PDEs). PDEs are from three enzyme classes: carbohydrate esterases from CE8 and CE12 family, glycoside hydrolases from GH28 family and lyases from PL1, 2, 3, 9 and 10. We have reviewed the literature related to abundance and structure-function of these abovementioned enzymes from bacteria. From the current available literature, we found very limited information is present about thermostable PDEs. Hence, in future it could be a topic of study to gain the insight about structure-function of enzymes together with the expanded role of thermostable enzymes in development of bioprocesses based on these enzymes.

Influence of a crown-gall tumor initiation enhancer on bacterial attachment to the host plant cell wall

Planta ◽  
1982 ◽  
Vol 156 (4) ◽  
pp. 364-368 ◽  
Author(s):  
A. -M. Bouckaert-Urban ◽  
G. Brouwers ◽  
L. Thoelen ◽  
J. C. Vendrig
Keyword(s):  
Cell Wall ◽  
Host Plant ◽  
Plant Cell ◽  
Crown Gall ◽  
Plant Cell Wall ◽  
Bacterial Attachment ◽  
Tumor Initiation ◽  
Crown Gall Tumor

scholarly journals Direct Target Network of the Neurospora crassa Plant Cell Wall Deconstruction Regulators CLR-1, CLR-2, and XLR-1

mBio ◽  
2015 ◽  
Vol 6 (5) ◽  
Author(s):  
James P. Craig ◽  
Samuel T. Coradetti ◽  
Trevor L. Starr ◽  
N. Louise Glass
Keyword(s):  
Gene Expression ◽  
Cell Wall ◽  
Transcription Factors ◽  
Neurospora Crassa ◽  
Plant Cell ◽  
Plant Cell Wall ◽  
Nutrient Sensing ◽  
Wall Material ◽  
Content Type ◽  
Genes Encoding

ABSTRACTFungal deconstruction of the plant cell requires a complex orchestration of a wide array of intracellular and extracellular enzymes. InNeurospora crassa, CLR-1, CLR-2, and XLR-1 have been identified as key transcription factors regulating plant cell wall degradation in response to soluble sugars. The XLR-1 regulon was defined using a constitutively active mutant allele, resulting in hemicellulase gene expression and secretion under noninducing conditions. To define genes directly regulated by CLR-1, CLR-2, and XLR-1, we performed chromatin immunoprecipitation and next-generation sequencing (ChIPseq) on epitope-tagged constructs of these three transcription factors. WhenN. crassais exposed to plant cell wall material, CLR-1, CLR-2, and XLR-1 individually bind to the promoters of the most strongly induced genes in their respective regulons. These include promoters of genes encoding cellulases for CLR-1 and CLR-2 (CLR-1/CLR-2) and promoters of genes encoding hemicellulases for XLR-1. CLR-1 bound to its regulon under noninducing conditions; however, this binding alone did not translate into gene expression and enzyme secretion. Motif analysis of the bound genes revealed conserved DNA binding motifs, with the CLR-2 motif matching that of its closest paralog inSaccharomyces cerevisiae, Gal4p. Coimmunoprecipitation studies showed that CLR-1 and CLR-2 act in a homocomplex but not as a CLR-1/CLR-2 heterocomplex.IMPORTANCEUnderstanding fungal regulation of complex plant cell wall deconstruction pathways in response to multiple environmental signals via interconnected transcriptional circuits provides insight into fungus/plant interactions and eukaryotic nutrient sensing. Coordinated optimization of these regulatory networks is likely required for optimal microbial enzyme production.

scholarly journals A pair of esterases from a commensal gut bacterium remove acetylations from all positions on complex β-mannans

2019 ◽  
Author(s):  
Leszek Michalak ◽  
Sabina Leanti La Rosa ◽  
Shaun Allan Leivers ◽  
Lars Jordhøy Lindstad ◽  
Åsmund Røhr Kjendseth ◽  
...  
Keyword(s):  
Cell Wall ◽  
Plant Cell ◽  
Active Site ◽  
Plant Cell Wall ◽  
3D Structure ◽  
Domain Architecture ◽  
Catalytic Triad ◽  
Glycoside Hydrolases ◽  
Time Resolved ◽  
Mannose Residue

Abstractβ-Mannans and xylans are important components of the plant cell wall and they are acetylated to be protected from degradation by glycoside hydrolases. β-Mannans are widely present in human and animal diets as fiber from leguminous plants and as thickeners and stabilizers in processed foods. There are many fully characterized acetylxylan esterases (AcXEs), however, the enzymes deacetylating mannans are less understood. Here we present two carbohydrate esterases, RiCE2 and RiCEX, from the Firmicute Roseburia intestinalis, which together deacetylate complex galactoglucomannan (GGM). The 3D-structure of RiCEX with a mannopentaose in the active site shows that the CBM35 domain of RiCEX forms a confined complex, where the axially oriented C2-hydroxyl of a mannose residue points towards the Ser41 of the catalytic triad. Cavities on the RiCEX surface may accept galactosylations at the C6 positions of mannose adjacent to the mannose residue being deacetylated (subsite −1 and +1). In depth characterization of the two enzymes using time-resolved NMR, HPLC and mass spectrometry demonstrates that they work in a complementary manner. RiCEX exclusively removes the axially oriented 2-O-acetylations on any mannose residue in an oligosaccharide, including double acetylated mannoses, while the RiCE2 is active on 3-O-, 4-O- and 6-O-acetylations. Activity of RiCE2 is dependent on RiCEX removing 2-O-acetylations from double acetylated mannose. Furthermore, transacetylation of oligosaccharides with the 2-O specific RiCEX provided new insight to how temperature and pH affects acetyl migration on mannooligosaccharides.Significance statementAcetylations are an important feature of hemicellulose, altering the physical properties of the plant cell wall, and limiting enzyme accessibility. Removal of acetyl groups from beta-mannan is a key step towards efficient utilization of mannans as a carbon source for gut microbiota and in biorefineries. We present detailed insight into mannan deacetylation by two highly substrate-specific acetyl-mannan esterases (AcMEs) from a prevalent gut commensal Firmicute, which cooperatively deacetylate complex galactoglucomannan. The 3D structure of RiCEX with mannopentaose in the active site has a unique two-domain architecture including a CBM35 and an SGNH superfamily hydrolytic domain. Discovery of mannan specific esterases improves the understanding of an important step in dietary fiber utilization by gut commensal Firmicutes.

scholarly journals The Role of Glycoside Hydrolases in Phytopathogenic Fungi and Oomycetes Virulence

2021 ◽  
Vol 22 (17) ◽  
pp. 9359
Author(s):  
Vahideh Rafiei ◽  
Heriberto Vélëz ◽  
Georgios Tzelepis
Keyword(s):  
Cell Wall ◽  
Plant Cell Wall ◽  
Hydrolytic Enzymes ◽  
Fungal Species ◽  
Phytopathogenic Fungi ◽  
Glycoside Hydrolases ◽  
Cell Wall Degrading Enzymes ◽  
Plant Host ◽  
Successful Infection ◽  
Molecular Patterns

Phytopathogenic fungi need to secrete different hydrolytic enzymes to break down complex polysaccharides in the plant cell wall in order to enter the host and develop the disease. Fungi produce various types of cell wall degrading enzymes (CWDEs) during infection. Most of the characterized CWDEs belong to glycoside hydrolases (GHs). These enzymes hydrolyze glycosidic bonds and have been identified in many fungal species sequenced to date. Many studies have shown that CWDEs belong to several GH families and play significant roles in the invasion and pathogenicity of fungi and oomycetes during infection on the plant host, but their mode of function in virulence is not yet fully understood. Moreover, some of the CWDEs that belong to different GH families act as pathogen-associated molecular patterns (PAMPs), which trigger plant immune responses. In this review, we summarize the most important GHs that have been described in eukaryotic phytopathogens and are involved in the establishment of a successful infection.

scholarly journals Specific Xylan Activity Revealed for AA9 Lytic Polysaccharide Monooxygenases of the Thermophilic Fungus Malbranchea cinnamomea by Functional Characterization

2019 ◽  
Vol 85 (23) ◽  
Author(s):  
Silvia Hüttner ◽  
Anikó Várnai ◽  
Dejan M. Petrović ◽  
Cao Xuan Bach ◽  
Dang Thi Kim Anh ◽  
...  
Keyword(s):  
Cell Wall ◽  
Plant Cell ◽  
Plant Cell Wall ◽  
Functional Characterization ◽  
Cellulose Microfibrils ◽  
Cell Wall Polysaccharide ◽  
Poor Growth ◽  
Content Type ◽  
Lytic Polysaccharide Monooxygenases ◽  
Polysaccharide Monooxygenases

ABSTRACT The thermophilic biomass-degrader Malbranchea cinnamomea exhibits poor growth on cellulose but excellent growth on hemicelluloses as the sole carbon source. This is surprising considering that its genome encodes eight lytic polysaccharide monooxygenases (LPMOs) from auxiliary activity family 9 (AA9), enzymes known for their high potential in accelerating cellulose depolymerization. We characterized four of the eight (M. cinnamomea AA9s) McAA9s, namely, McAA9A, McAA9B, McAA9F, and McAA9H, to gain a deeper understanding about their roles in the fungus. The characterized McAA9s were active on hemicelluloses, including xylan, glucomannan, and xyloglucan, and furthermore, in accordance with transcriptomics data, differed in substrate specificity. Of the McAA9s, McAA9H is unique, as it preferentially cleaves residual xylan in phosphoric acid-swollen cellulose (PASC). Moreover, when exposed to cellulose-xylan blends, McAA9H shows a preference for xylan and for releasing (oxidized) xylooligosaccharides. The cellulose dependence of the xylan activity suggests that a flat conformation, with rigidity similar to that of cellulose microfibrils, is a prerequisite for productive interaction between xylan and the catalytic surface of the LPMO. McAA9H showed a similar trend on xyloglucan, underpinning the suggestion that LPMO activity on hemicelluloses strongly depends on the polymers’ physicochemical context and conformation. Our results support the notion that LPMO multiplicity in fungal genomes relates to the large variety of copolymeric polysaccharide arrangements occurring in the plant cell wall. IMPORTANCE The Malbranchea cinnamomea LPMOs (McAA9s) showed activity on a broad range of soluble and insoluble substrates, suggesting their involvement in various steps of biomass degradation besides cellulose decomposition. Our results indicate that the fungal AA9 family is more diverse than originally thought and able to degrade almost any kind of plant cell wall polysaccharide. The discovery of an AA9 that preferentially cleaves xylan enhances our understanding of the physiological roles of LPMOs and enables the use of xylan-specific LPMOs in future applications.

scholarly journals Induction of Genes Encoding Plant Cell Wall-Degrading Carbohydrate-Active Enzymes by Lignocellulose-Derived Monosaccharides and Cellobiose in the White-Rot FungusDichomitus squalens

2018 ◽  
Vol 84 (11) ◽  
Author(s):  
Sara Casado López ◽  
Mao Peng ◽  
Tedros Yonatan Issak ◽  
Paul Daly ◽  
Ronald P. de Vries ◽  
...  
Keyword(s):  
Cell Wall ◽  
Plant Cell ◽  
Plant Cell Wall ◽  
Plant Biomass ◽  
Expression Patterns ◽  
Fine Tuning ◽  
White Rot ◽  
White Rot Fungus ◽  
Content Type ◽  
Dichomitus Squalens

ABSTRACTFungi can decompose plant biomass into small oligo- and monosaccharides to be used as carbon sources. Some of these small molecules may induce metabolic pathways and the production of extracellular enzymes targeted for degradation of plant cell wall polymers. Despite extensive studies in ascomycete fungi, little is known about the nature of inducers for the lignocellulolytic systems of basidiomycetes. In this study, we analyzed six sugars known to induce the expression of lignocellulolytic genes in ascomycetes for their role as inducers in the basidiomycete white-rot fungusDichomitus squalensusing a transcriptomic approach. This identified cellobiose andl-rhamnose as the main inducers of cellulolytic and pectinolytic genes, respectively, ofD. squalens. Our results also identified differences in gene expression patterns between dikaryotic and monokaryotic strains ofD. squalenscultivated on plant biomass-derived monosaccharides and the disaccharide cellobiose. This suggests that despite conservation of the induction between these two genetic forms ofD. squalens, the fine-tuning in the gene regulation of lignocellulose conversion is differently organized in these strains.IMPORTANCEWood-decomposing basidiomycete fungi have a major role in the global carbon cycle and are promising candidates for lignocellulosic biorefinery applications. However, information on which components trigger enzyme production is currently lacking, which is crucial for the efficient use of these fungi in biotechnology. In this study, transcriptomes of the white-rot fungusDichomitus squalensfrom plant biomass-derived monosaccharide and cellobiose cultures were studied to identify compounds that induce the expression of genes involved in plant biomass degradation.

scholarly journals Crystal Structure and Substrate Specificity Modification of Acetyl Xylan Esterase from Aspergillus luchuensis

2017 ◽  
Vol 83 (20) ◽  
Author(s):  
Dai Komiya ◽  
Akane Hori ◽  
Takuya Ishida ◽  
Kiyohiko Igarashi ◽  
Masahiro Samejima ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Cell Wall ◽  
Substrate Specificity ◽  
Ferulic Acid ◽  
Plant Cell ◽  
Plant Cell Wall ◽  
Catalytic Triad ◽  
Acetyl Xylan Esterase ◽  
Content Type ◽  
Aspergillus Luchuensis

ABSTRACT Acetyl xylan esterase (AXE) catalyzes the hydrolysis of the acetyl bonds present in plant cell wall polysaccharides. Here, we determined the crystal structure of AXE from Aspergillus luchuensis (AlAXEA), providing the three-dimensional structure of an enzyme in the Esterase_phb family. AlAXEA shares its core α/β-hydrolase fold structure with esterases in other families, but it has an extended central β-sheet at both its ends and an extra loop. Structural comparison with a ferulic acid esterase (FAE) from Aspergillus niger indicated that AlAXEA has a conserved catalytic machinery: a catalytic triad (Ser119, His259, and Asp202) and an oxyanion hole (Cys40 and Ser120). Near the catalytic triad of AlAXEA, two aromatic residues (Tyr39 and Trp160) form small pockets at both sides. Homology models of fungal FAEs in the same Esterase_phb family have wide pockets at the corresponding sites because they have residues with smaller side chains (Pro, Ser, and Gly). Mutants with site-directed mutations at Tyr39 showed a substrate specificity similar to that of the wild-type enzyme, whereas those with mutations at Trp160 acquired an expanded substrate specificity. Interestingly, the Trp160 mutants acquired weak but significant type B-like FAE activity. Moreover, the engineered enzymes exhibited ferulic acid-releasing activity from wheat arabinoxylan. IMPORTANCE Hemicelluloses in the plant cell wall are often decorated by acetyl and ferulic acid groups. Therefore, complete and efficient degradation of plant polysaccharides requires the enzymes for cleaving the side chains of the polymer. Since the Esterase_phb family contains a wide array of fungal FAEs and AXEs from fungi and bacteria, our study will provide a structural basis for the molecular mechanism of these industrially relevant enzymes in biopolymer degradation. The structure of the Esterase_phb family also provides information for bacterial polyhydroxyalkanoate depolymerases that are involved in biodegradation of thermoplastic polymers.

scholarly journals Insights into Plant Cell Wall Degradation from the Genome Sequence of the Soil Bacterium Cellvibrio japonicus

2008 ◽  
Vol 190 (15) ◽  
pp. 5455-5463 ◽  
Author(s):  
Robert T. DeBoy ◽  
Emmanuel F. Mongodin ◽  
Derrick E. Fouts ◽  
Louise E. Tailford ◽  
Hoda Khouri ◽  
...  
Keyword(s):  
Cell Wall ◽  
Plant Cell ◽  
Plant Cell Wall ◽  
Hydrolytic Enzymes ◽  
Soil Bacterium ◽  
Glycoside Hydrolases ◽  
Carbohydrate Binding ◽  
Carbohydrate Binding Modules ◽  
Cellvibrio Japonicus ◽  
And Storage

ABSTRACT The plant cell wall, which consists of a highly complex array of interconnecting polysaccharides, is the most abundant source of organic carbon in the biosphere. Microorganisms that degrade the plant cell wall synthesize an extensive portfolio of hydrolytic enzymes that display highly complex molecular architectures. To unravel the intricate repertoire of plant cell wall-degrading enzymes synthesized by the saprophytic soil bacterium Cellvibrio japonicus, we sequenced and analyzed its genome, which predicts that the bacterium contains the complete repertoire of enzymes required to degrade plant cell wall and storage polysaccharides. Approximately one-third of these putative proteins (57) are predicted to contain carbohydrate binding modules derived from 13 of the 49 known families. Sequence analysis reveals approximately 130 predicted glycoside hydrolases that target the major structural and storage plant polysaccharides. In common with that of the colonic prokaryote Bacteroides thetaiotaomicron, the genome of C. japonicus is predicted to encode a large number of GH43 enzymes, suggesting that the extensive arabinose decorations appended to pectins and xylans may represent a major nutrient source, not just for intestinal bacteria but also for microorganisms that occupy terrestrial ecosystems. The results presented here predict that C. japonicus possesses an extensive range of glycoside hydrolases, lyases, and esterases. Most importantly, the genome of C. japonicus is remarkably similar to that of the gram-negative marine bacterium, Saccharophagus degradans 2-40T. Approximately 50% of the predicted C. japonicus plant-degradative apparatus appears to be shared with S. degradans, consistent with the utilization of plant-derived complex carbohydrates as a major substrate by both organisms.

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