A multifunctional GH39 glycoside hydrolase from the anaerobic gut fungus Orpinomyces sp. strain C1A

Background.The anaerobic gut fungi (phylum Neocallimastigomycota) represent a promising source of novel lignocellulolytic enzymes. Here, we report on the cloning, expression, and characterization of a glycoside hydrolase family 39 (GH39) enzyme (Bgxg1) that is highly transcribed by the anaerobic fungusOrpinomycessp. strain C1A under different growth conditions. This represents the first study of a GH39-family enzyme from the anaerobic fungi.Methods.Using enzyme activity assays, we performed a biochemical characterization of Bgxg1 on a variety of substrates over a wide range of pH and temperature values to identify the optimal enzyme conditions and the specificity of the enzyme. In addition, substrate competition studies and comparative modeling efforts were completed.Results.Contrary to the narrow range of activities (β-xylosidase or α-L-iduronidase) observed in previously characterized GH39 enzymes, Bgxg1 is unique in that it is multifunctional, exhibiting strong β-xylosidase, β-glucosidase, β-galactosidase activities (11.5 ± 1.2, 73.4 ± 7.15, and 54.6 ± 2.26 U/mg, respectively) and a weak xylanase activity (10.8 ± 1.25 U/mg), as compared to previously characterized enzymes. Further, Bgxg1 possesses extremely high affinity (as evident by the lowestKmvalues), compared to all previously characterized β-glucosidases, β-galactosidases, and xylanases. Physiological characterization revealed that Bgxg1 is active over a wide range of pH (3–8, optimum 6) and temperatures (25–60 °C, optimum 39 °C), and possesses excellent temperature and thermal stability. Substrate competition assays suggest that all observed activities occur at a single active site. Using comparative modeling and bioinformatics approaches, we putatively identified ten amino acid differences between Bgxg1 and previously biochemically characterized GH39 β-xylosidases that we speculate could impact active site architecture, size, charge, and/or polarity.Discussion.Collectively, the unique capabilities and multi-functionality of Bgxg1 render it an excellent candidate for inclusion in enzyme cocktails mediating cellulose and hemicellulose saccharification from lignocellulosic biomass.

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A multifunctional GH39 glycoside hydrolase from the anaerobic gut fungus Orpinomyces sp. strain C1A

10.7287/peerj.preprints.2076v1 ◽

2016 ◽

Cited By ~ 1

Author(s):

Jessica M Morrison ◽

Mostafa S Elshahed ◽

Noha Youssef

Keyword(s):

Active Site ◽

Glycoside Hydrolase ◽

Biochemical Characterization ◽

Xylanase Activity ◽

Comparative Modeling ◽

Glycoside Hydrolase Family ◽

Wide Range ◽

Promising Source ◽

Substrate Competition

Background. The anaerobic gut fungi (phylum Neocallimastigomycota) represent a promising source of novel lignocellulolytic enzymes. Here, we report on the cloning, expression, and characterization of a glycoside hydrolase family 39 (GH39) enzyme (Bgxg1) that is highly transcribed by the anaerobic fungus Orpinomyces sp. strain C1A under different growth conditions. This represents the first study of a GH39-family enzyme from the anaerobic fungi. Methods. Using enzyme activity assays, we performed a biochemical characterization of Bgxg1 on a variety of substrates over a wide range of pH and temperature values to identify the optimal enzyme conditions and the specificity of the enzyme. In addition, substrate competition studies and comparative modeling efforts were completed. Results. Contrary to the narrow range of activities (β-xylosidase or α-L-iduronidase) observed in previously characterized GH39 enzymes, Bgxg1 is unique in that it is multifunctional, exhibiting strong β-xylosidase, β-glucosidase, β-galactosidase activities (11.5 ± 1.2, 73.4 ± 7.15, and 54.6 ± 2.26 U/mg, respectively) and a weak xylanase activity (10.8 ± 1.25 U/mg), strength determined as compared to previously characterized enzymes. Physiological characterization revealed that Bgxg1 is active over a wide range of pH (3-8, optimum 6) and temperatures (25-60°C, optimum 39°C), and possesses excellent temperature and thermal stability. Substrate competition assays suggest that all observed activities occur at a single active site. Using comparative modeling and bioinformatics approaches, we putatively identified ten amino acid differences between Bgxg1 and previously biochemically characterized GH39 β-xylosidases that we speculate could impact active site architecture, size, charge, and/or polarity. The putative contributions of these changes to the observed relaxed specificities in Bgxg1 are discussed. Discussion. Collectively, the unique capabilities and multi-functionality of Bgxg1 render it an excellent candidate for inclusion in enzyme cocktails mediating cellulose and hemicellulose saccharification from lignocellulosic biomass.

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Characterization of Cross-Linked Enzyme Aggregates of the Y509E Mutant of a Glycoside Hydrolase Family 52 β-xylosidase from G. stearothermophilus

Molecules ◽

10.3390/molecules26020451 ◽

2021 ◽

Vol 26 (2) ◽

pp. 451

Author(s):

Gabriela Romero ◽

Lellys M. Contreras ◽

Carolina Aguirre ◽

Jeff Wilkesman ◽

Josefa María Clemente-Jiménez ◽

...

Keyword(s):

Ammonium Sulfate ◽

Glycoside Hydrolase ◽

Biochemical Characterization ◽

Xylanase Activity ◽

Immobilized Enzymes ◽

Cross Linking ◽

Glycoside Hydrolase Family ◽

Km Value ◽

Hydrolase Family

Cross-linked enzyme aggregates (CLEAs) of the Y509E mutant of glycoside hydrolase family 52 β-xylosidase from Geobacillus stearothermophilus with dual activity of β-xylosidase and xylanase (XynB2Y509E) were prepared. Ammonium sulfate was used as the precipitant agent, and glutaraldehyde as cross-linking agent. The optimum conditions were found to be 90% ammonium sulfate, 12.5 mM glutaraldehyde, 3 h of cross-linking reaction at 25 °C, and pH 8.5. Under these (most effective) conditions, XynB2Y509E-CLEAs retained 92.3% of their original β-xylosidase activity. Biochemical characterization of both crude and immobilized enzymes demonstrated that the maximum pH and temperature after immobilization remained unchanged (pH 6.5 and 65 °C). Moreover, an improvement in pH stability and thermostability was also found after immobilization. Analysis of kinetic parameters shows that the Km value of XynB2Y509E-CLEAs obtained was slightly higher than that of free XynB2Y509E (1.2 versus 0.9 mM). Interestingly, the xylanase activity developed by the mutation was also conserved after the immobilization process.

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Biochemical characterization of a glycoside hydrolase family 43 β-D-galactofuranosidase from the fungus Aspergillus niger

10.1101/2021.10.27.466152 ◽

2021 ◽

Author(s):

Gregory S Bulmer ◽

Fang Wei Yuen ◽

Naimah Begum ◽

Bethan S Jones ◽

Sabine S Flitsch ◽

...

Keyword(s):

Aspergillus Niger ◽

Glycoside Hydrolase ◽

Biochemical Characterization ◽

Maximum Activity ◽

Glycoside Hydrolase Family ◽

Enzyme Specificity ◽

Fungal Enzymes ◽

Glycoside Hydrolase Family 43 ◽

Hydrolase Family

β-D-Galactofuranose (Galf) and its polysaccharides are found in bacteria, fungi and protozoa but do not occur in mammalian tissues, and thus represent a specific target for anti-pathogenic drugs. Understanding the enzymatic degradation of these polysaccharides is therefore of great interest, but the identity of fungal enzymes with exclusively galactofuranosidase activity has so far remained elusive. Here we describe the identification and characterization of a galactofuranosidase from the industrially important fungus Aspergillus niger. Phylogenetic analysis of glycoside hydrolase family 43 subfamily 34 (GH43_34) members revealed the occurrence of three distinct clusters and, by comparison with specificities of characterized bacterial members, suggested a basis for prediction of enzyme specificity. Using this rationale, in tandem with molecular docking, we identified a putative β-D-galactofuranosidase from A. niger which was recombinantly expressed in Escherichia coli. The Galf-specific hydrolase, encoded by xynD demonstrates maximum activity at pH 5, 25 °C towards 4-Nitrophenyl-β-galactofuranoside (pNP-βGalf), with a Km of 17.9 ± 1.9 mM and Vmax of 70.6 ± 5.3 μmol min-1. The characterization of this first fungal GH43 galactofuranosidase offers further molecular insight into the degradation of Galf-containing structures and may inform clinical treatments against fungal pathogens.

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Structural and functional studies of the glycoside hydrolase family 3 β-glucosidase Cel3A from the moderately thermophilic fungusRasamsonia emersonii

Acta Crystallographica Section D Structural Biology ◽

10.1107/s2059798316008482 ◽

2016 ◽

Vol 72 (7) ◽

pp. 860-870 ◽

Cited By ~ 16

Author(s):

Mikael Gudmundsson ◽

Henrik Hansson ◽

Saeid Karkehabadi ◽

Anna Larsson ◽

Ingeborg Stals ◽

...

Keyword(s):

Glycoside Hydrolase ◽

Biochemical Characterization ◽

Cellulosic Biomass ◽

Glycoside Hydrolase Family ◽

Hypocrea Jecorina ◽

Moderately Thermophilic ◽

Functional Studies ◽

Excellent Candidate ◽

Hydrolase Family

The filamentous fungusHypocrea jecorinaproduces a number of cellulases and hemicellulases that act in a concerted fashion on biomass and degrade it into monomeric or oligomeric sugars. β-Glucosidases are involved in the last step of the degradation of cellulosic biomass and hydrolyse the β-glycosidic linkage between two adjacent molecules in dimers and oligomers of glucose. In this study, it is shown that substituting the β-glucosidase fromH. jecorina(HjCel3A) with the β-glucosidase Cel3A from the thermophilic fungusRasamsonia emersonii(ReCel3A) in enzyme mixtures results in increased efficiency in the saccharification of lignocellulosic materials. Biochemical characterization ofReCel3A, heterologously produced inH. jecorina, reveals a preference for disaccharide substrates over longer gluco-oligosaccharides. Crystallographic studies ofReCel3A revealed a highly N-glycosylated three-domain dimeric protein, as has been observed previously for glycoside hydrolase family 3 β-glucosidases. The increased thermal stability and saccharification yield and the superior biochemical characteristics ofReCel3A compared withHjCel3A and mixtures containingHjCel3A makeReCel3A an excellent candidate for addition to enzyme mixtures designed to operate at higher temperatures.

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