scholarly journals Two Novel α-L-Arabinofuranosidases from Bifidobacterium longum subsp. longum belonging to Glycoside Hydrolase Family 43 Cooperatively Degrade Arabinan

2018 ◽  
Author(s):  
Masahiro Komeno ◽  
Honoka Hayamizu ◽  
Kiyotaka Fujita ◽  
Hisashi Ashida

ABSTRACTArabinose-containing poly-or oligosaccharides are suitable carbohydrate sources for Bifidobacterium longum subsp. longum, though their degradation pathways are poorly understood. In this study, we found that the gene expression levels of bllj 1852 and bllj 1853 from B. longum subsp. longum JCM 1217 were enhanced in the presence of arabinan. Both genes encode previously uncharacterized glycoside hydrolase (GH) family 43 enzymes. Subsequently, we cloned those genes and characterized the recombinant enzymes expressed in Escherichia coli. Both enzymes exhibited α-L-arabinofuranosidase activity toward synthetic p-nitrophenyl glycoside, but the specificities for L-arabinofuranosyl linkages were different. BLLJ_1852 catalyzed the hydrolysis of α1,2- and α1,3-L-arabinofuranosyl linkages found in the side chains of arabinan and arabinoxylan. BLLJ_1852 released L-arabinose 100 times faster from arabinan than from arabinoxylan but did not act on arabinogalactan. BLLJ_1853 catalyzed the hydrolysis of α1,5-L-arabinofuranosyl linkages found on the arabinan backbone. BLLJ_1853 released L-arabinose from arabinan but not from arabinoxylan or arabinogalactan. Both enzyme activities were largely suppressed with EDTA treatment, suggesting that they require divalent metal ions. BLLJ_1852 was moderately activated in the presence of all divalent cations tested, whereas BLLJ_1853 activity was inhibited by Cu2+. The GH43 domains of BLLJ_1852 and BLLJ_1853 are classified into GH43 subfamilies 27 and 22, respectively, but hardly share similarity with other biochemically characterized members in the corresponding subfamilies.IMPORTANCEWe identified two novel α-L-arabinofuranosidases from B. longum subsp. longum JCM 1217 that act on different linkages in arabinan. These enzymes may be required for efficient degradation and assimilation of arabinan in the probiotic bifidobacteria. The genes encoding these enzymes are located side-by-side in a gene cluster involved in metabolic pathways for plant-derived polysaccharides, which may confer adaptability in adult intestines.

2019 ◽  
Vol 85 (6) ◽  
Author(s):  
Masahiro Komeno ◽  
Honoka Hayamizu ◽  
Kiyotaka Fujita ◽  
Hisashi Ashida

ABSTRACT Arabinose-containing poly- or oligosaccharides are suitable carbohydrate sources for Bifidobacterium longum subsp. longum. However, their degradation pathways are poorly understood. In this study, we cloned and characterized the previously uncharacterized glycoside hydrolase family 43 (GH43) enzymes B. longum subsp. longum ArafC (BlArafC; encoded by BLLJ_1852) and B. longum subsp. longum ArafB (BlArafB; encoded by BLLJ_1853) from B. longum subsp. longum JCM 1217. Both enzymes exhibited α-l-arabinofuranosidase activity toward p-nitrophenyl-α-l-arabinofuranoside but no activity toward p-nitrophenyl-β-d-xylopyranoside. The specificities of the two enzymes for l-arabinofuranosyl linkages were different. BlArafC catalyzed the hydrolysis of α1,2- and α1,3-l-arabinofuranosyl linkages found on the side chains of both arabinan and arabinoxylan. It released l-arabinose 100 times faster from arabinan than from arabinoxylan but did not act on arabinogalactan. On the other hand, BlArafB catalyzed the hydrolysis of the α1,5-l-arabinofuranosyl linkage found on the arabinan backbone. It released l-arabinose from arabinan but not from arabinoxylan or arabinogalactan. Coincubation of BlArafC and BlArafB revealed that these two enzymes are able to degrade arabinan in a synergistic manner. Both enzyme activities were suppressed with EDTA treatment, suggesting that they require divalent metal ions. The GH43 domains of BlArafC and BlArafB are classified into GH43 subfamilies 27 and 22, respectively, but show very low similarity (less than 15% identity) with other biochemically characterized members in the corresponding subfamilies. The B. longum subsp. longum strain lacking the GH43 gene cluster that includes BLLJ_1850 to BLLJ_1853 did not grow in arabinan medium, suggesting that BlArafC and BlArafB are important for assimilation of arabinan. IMPORTANCE We identified two novel α-l-arabinofuranosidases, BlArafC and BlArafB, from B. longum subsp. longum JCM 1217, both of which are predicted to be extracellular membrane-bound enzymes. The former specifically acts on α1,2/3-l-arabinofuranosyl linkages, while the latter acts on the α1,5-l-arabinofuranosyl linkage. These enzymes cooperatively degrade arabinan and are required for the efficient growth of bifidobacteria in arabinan-containing medium. The genes encoding these enzymes are located side by side in a gene cluster involved in metabolic pathways for plant-derived polysaccharides, which may confer adaptability in adult intestines.


2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Yuya Kuritani ◽  
Kohei Sato ◽  
Hideo Dohra ◽  
Seiichiro Umemura ◽  
Motomitsu Kitaoka ◽  
...  

AbstractLevoglucosan (LG) is an anhydrosugar produced through glucan pyrolysis and is widely found in nature. We previously isolated an LG-utilizing thermophile, Bacillus smithii S-2701M, and suggested that this bacterium may have a metabolic pathway from LG to glucose, initiated by LG dehydrogenase (LGDH). Here, we completely elucidated the metabolic pathway of LG involving three novel enzymes in addition to LGDH. In the S-2701M genome, three genes expected to be involved in the LG metabolism were found in the vicinity of the LGDH gene locus. These four genes including LGDH gene (lgdA, lgdB1, lgdB2, and lgdC) were expressed in Escherichia coli and purified to obtain functional recombinant proteins. Thin layer chromatography analyses of the reactions with the combination of the four enzymes elucidated the following metabolic pathway: LgdA (LGDH) catalyzes 3-dehydrogenation of LG to produce 3-keto-LG, which undergoes β-elimination of 3-keto-LG by LgdB1, followed by hydration to produce 3-keto-d-glucose by LgdB2; next, LgdC reduces 3-keto-d-glucose to glucose. This sequential reaction mechanism resembles that proposed for an enzyme belonging to glycoside hydrolase family 4, and results in the observational hydrolysis of LG into glucose with coordination of the four enzymes.


Glycobiology ◽  
2013 ◽  
Vol 24 (2) ◽  
pp. 208-216 ◽  
Author(s):  
A. H. Viborg ◽  
T. Katayama ◽  
M. Abou Hachem ◽  
M. C. Andersen ◽  
M. Nishimoto ◽  
...  

2002 ◽  
Vol 68 (11) ◽  
pp. 5765-5768 ◽  
Author(s):  
Amber Vanden Wymelenberg ◽  
Stuart Denman ◽  
Diane Dietrich ◽  
Jennifer Bassett ◽  
Xiaochun Yu ◽  
...  

ABSTRACT Phanerochaete chrysosporium cellulase genes were cloned and characterized. The cel61A product was structurally similar to fungal endoglucanases of glycoside hydrolase family 61, whereas the cel9A product revealed similarities to Thermobifida fusca Cel9A (E4), an enzyme with both endo- and exocellulase characteristics. The fungal Cel9A is apparently a membrane-bound protein, which is very unusual for microbial cellulases. Transcript levels of both genes were substantially higher in cellulose-grown cultures than in glucose-grown cultures. These results show that P. chrysosporium possesses a wide array of conventional and unconventional cellulase genes.


2019 ◽  
Vol 18 (1) ◽  
Author(s):  
Laura Plaza-Vinuesa ◽  
Oswaldo Hernandez-Hernandez ◽  
F. Javier Moreno ◽  
Blanca de las Rivas ◽  
Rosario Muñoz

Abstract Background α-Amylases specifically catalyse the hydrolysis of the internal α-1, 4-glucosidic linkages of starch. Glycoside hydrolase (GH) family 13 is the main α-amylase family in the carbohydrate-active database. Lactobacillus plantarum WCFS1 possesses eleven proteins included in GH13 family. Among these, proteins annotated as maltose-forming α-amylase (Lp_0179) and maltogenic α-amylase (Lp_2757) were included. Results In this study, Lp_0179 and Lp_2757 L. plantarum α-amylases were structurally and biochemically characterized. Lp_2757 displayed structural features typical of GH13_20 subfamily which were absent in Lp_0179. Genes encoding Lp_0179 (Amy2) and Lp_2757 were cloned and overexpressed in Escherichia coli BL21(DE3). Purified proteins showed high hydrolytic activity on pNP-α-D-maltopyranoside, being the catalytic efficiency of Lp_0179 remarkably higher. In relation to the hydrolysis of starch-related carbohydrates, Lp_0179 only hydrolysed maltopentaose and dextrin, demonstrating that is an exotype glucan hydrolase. However, Lp_2757 was also able to hydrolyze cyclodextrins and other non-cyclic oligo- and polysaccharides, revealing a great preference towards α-1,4-linkages typical of maltogenic amylases. Conclusions The substrate range as well as the biochemical properties exhibited by Lp_2757 maltogenic α-amylase suggest that this enzyme could be a very promising enzyme for the hydrolysis of α-1,4 glycosidic linkages present in a broad number of starch-carbohydrates, as well as for the investigation of an hypothetical transglucosylation activity under appropriate reaction conditions.


2002 ◽  
Vol 184 (15) ◽  
pp. 4124-4133 ◽  
Author(s):  
Kaveh Emami ◽  
Tibor Nagy ◽  
Carlos M. G. A. Fontes ◽  
Luis M. A. Ferreira ◽  
Harry J. Gilbert

ABSTRACT Pseudomonas cellulosa is a highly efficient xylan-degrading bacterium. Genes encoding five xylanases, and several accessory enzymes, which remove the various side chains that decorate the xylan backbone, have been isolated from the pseudomonad and characterized. The xylanase genes consist of xyn10A, xyn10B, xyn10C, xyn10D, and xyn11A, which encode Xyn10A, Xyn10B, Xyn10C, Xyn10D, and Xyn11A, respectively. In this study a sixth xylanase gene, xyn11B, was isolated which encodes a 357-residue modular enzyme, designated Xyn11B, comprising a glycoside hydrolase family 11 catalytic domain appended to a C-terminal X-14 module, a homologue of which binds to xylan. Localization studies showed that the two xylanases with glycoside hydrolase family (GH) 11 catalytic modules, Xyn11A and Xyn11B, are secreted into the culture medium, whereas Xyn10C is membrane bound. xyn10C, xyn10D, xyn11A, and xyn11B were all abundantly expressed when the bacterium was cultured on xylan or β-glucan but not on medium containing mannan, whereas glucose repressed transcription of these genes. Although all of the xylanase genes were induced by the same polysaccharides, temporal regulation of xyn11A and xyn11B was apparent on xylan-containing media. Transcription of xyn11A occurred earlier than transcription of xyn11B, which is consistent with the predicted mode of action of the encoded enzymes. Xyn11A, but not Xyn11B, exhibits xylan esterase activity, and the removal of acetate side chains is required for xylanases to hydrolyze the xylan backbone. A transposon mutant of P. cellulosa in which xyn11A and xyn11B were inactive displayed greatly reduced extracellular but normal cell-associated xylanase activity, and its growth rate on medium containing xylan was indistinguishable from wild-type P. cellulosa. Based on the data presented here, we propose a model for xylan degradation by P. cellulosa in which the GH11 enzymes convert decorated xylans into substituted xylooligosaccharides, which are then hydrolyzed to their constituent sugars by the combined action of cell-associated GH10 xylanases and side chain-cleaving enzymes.


2014 ◽  
Vol 447 (1) ◽  
pp. 32-37 ◽  
Author(s):  
Tasuku Ito ◽  
Kyo Saikawa ◽  
Seonah Kim ◽  
Kiyotaka Fujita ◽  
Akihiro Ishiwata ◽  
...  

2016 ◽  
Vol 72 (1) ◽  
pp. 59-70 ◽  
Author(s):  
Min-Guan Lin ◽  
Meng-Chun Chi ◽  
Vankadari Naveen ◽  
Yi-Ching Li ◽  
Long-Liu Lin ◽  
...  

Trehalose-6-phosphate hydrolase (TreA) belongs to glycoside hydrolase family 13 (GH13) and catalyzes the hydrolysis of trehalose 6-phosphate (T6P) to yield glucose and glucose 6-phosphate. The products of this reaction can be further metabolized by the energy-generating glycolytic pathway. Here, crystal structures ofBacillus licheniformisTreA (BlTreA) and its R201Q mutant complexed withp-nitrophenyl-α-D-glucopyranoside (R201Q–pPNG) are presented at 2.0 and 2.05 Å resolution, respectively. The overall structure ofBlTreA is similar to those of other GH13 family enzymes. However, detailed structural comparisons revealed that the catalytic site ofBlTreA contains a long loop that adopts a different conformation from those of other GH13 family members. Unlike the homologous regions ofBacillus cereusoligo-1,6-glucosidase (BcOgl) andErwinia rhaponticiisomaltulose synthase (NX-5), the surface potential of theBlTreA active site exhibits a largely positive charge contributed by the four basic residues His281, His282, Lys284 and Lys292. Mutation of these residues resulted in significant decreases in the enzymatic activity ofBlTreA. Strikingly, the281HHLK284motif and Lys292 play critical roles in substrate discrimination byBlTreA.


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