A β‐mannan utilization locus in <i>Bacteroides ovatus</i> involves a GH36 α‐galactosidase active on galactomannans

Reddy, Sumitha K.; Bågenholm, Viktoria; Pudlo, Nicholas A.; Bouraoui, Hanene; Koropatkin, Nicole M.; Martens, Eric C.; Stålbrand, Henrik

doi:10.1002/1873-3468.12250

Cited by 39 publications

(61 citation statements)

References 42 publications

(84 reference statements)

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“…As described above, a putative β-mannan PUL was previously identified in B. ovatus ATCC 8483 ( bacova_02087–02097 ) and shown to be transcriptionally up-regulated when galactomannan or glucomannan was included in the culture medium (10, 34). This PUL contains the genes bacova_02092 and bacova_02093 , which encode the putative GH26 β-mannanases Bo Man26A and Bo Man26B, respectively.…”

Section: Resultsmentioning

confidence: 96%

“…To further investigate the mechanism of β-mannan degradation by B. ovatus , we determined the cellular location of Bo Man26A, Bo Man26B, and the α-galactosidase Bo Gal36A, the latter of which carries a signal peptidase I site but no membrane-attachment motif (34). Custom antibodies to the three recombinant proteins were used to detect surface expression in formaldehyde-fixed non-permeabilized B. ovatus grown in minimal media containing LBG galactomannan as a sole carbon source.…”

Section: Resultsmentioning

confidence: 99%

“…However, current knowledge on GHs and systems devoted to β-mannan hydrolysis and utilization is scarce (10, 34). Only a few such studies have been devoted to distinct GHs involved in β-mannan conversion in human gut bacteria (30, 32, 41).…”

Section: Discussionmentioning

confidence: 99%

“…The PUL was recently shown to have homologues in other B. ovatus and Bacteroides xylanisolvens strains (34). Furthermore, the PUL was predicted to encode putative GHs required for β-mannan degradation, including a family GH36 α-galactosidase ( Bo Gal36A) recently characterized by us (34). …”

Section: Introductionmentioning

confidence: 99%

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Galactomannan Catabolism Conferred by a Polysaccharide Utilization Locus of Bacteroides ovatus

Bågenholm

Reddy

Bouraoui

et al. 2017

Journal of Biological Chemistry

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156

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A recently identified polysaccharide utilization locus (PUL) from Bacteroides ovatus ATCC 8483 is transcriptionally up-regulated during growth on galacto- and glucomannans. It encodes two glycoside hydrolase family 26 (GH26) β-mannanases, BoMan26A and BoMan26B, and a GH36 α-galactosidase, BoGal36A. The PUL also includes two glycan-binding proteins, confirmed by β-mannan affinity electrophoresis. When this PUL was deleted, B. ovatus was no longer able to grow on locust bean galactomannan. BoMan26A primarily formed mannobiose from mannan polysaccharides. BoMan26B had higher activity on galactomannan with a high degree of galactosyl substitution and was shown to be endo-acting generating a more diverse mixture of oligosaccharides, including mannobiose. Of the two β-mannanases, only BoMan26B hydrolyzed galactoglucomannan. A crystal structure of BoMan26A revealed a similar structure to the exo-mannobiohydrolase CjMan26C from Cellvibrio japonicus, with a conserved glycone region (−1 and −2 subsites), including a conserved loop closing the active site beyond subsite −2. Analysis of cellular location by immunolabeling and fluorescence microscopy suggests that BoMan26B is surface-exposed and associated with the outer membrane, although BoMan26A and BoGal36A are likely periplasmic. In light of the cellular location and the biochemical properties of the two characterized β-mannanases, we propose a scheme of sequential action by the glycoside hydrolases encoded by the β-mannan PUL and involved in the β-mannan utilization pathway in B. ovatus. The outer membrane-associated BoMan26B initially acts on the polysaccharide galactomannan, producing comparably large oligosaccharide fragments. Galactomanno-oligosaccharides are further processed in the periplasm, degalactosylated by BoGal36A, and subsequently hydrolyzed into mainly mannobiose by the β-mannanase BoMan26A.

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Section: Resultsmentioning

confidence: 96%

Section: Resultsmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Galactomannan Catabolism Conferred by a Polysaccharide Utilization Locus of Bacteroides ovatus

Bågenholm

Reddy

Bouraoui

et al. 2017

Journal of Biological Chemistry

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156

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“…A pair of xylan-targeting PULs from B. ovatus, PUL-XylS and PUL-XylL, was found to encode enzymes tailored for individual plant ␤-xylans that varied in their composition and branching (79). Recently, the detailed genetic, biochemical, and enzyme structural characterization of a galactomannanspecific PUL from B. ovatus revealed the interplay of two mannan-specific SGBPs, two GH26 endo-␤-mannanases, and a GH36 exo-␣-galactosidase in the deconstruction of this plant cell wall polysaccharide (110,111). Among environmental bacteria, a complex chitin utilization locus from Flavobacterium johnsoniae has been extensively functionally characterized (112).…”

Section: Insight From Integrated Functional Characterizationmentioning

confidence: 99%

Polysaccharide Utilization Loci: Fueling Microbial Communities

et al. 2017

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The complex carbohydrates of terrestrial and marine biomass represent a rich nutrient source for free-living and mutualistic microbes alike. The enzymatic saccharification of these diverse substrates is of critical importance for fueling a variety of complex microbial communities, including marine, soil, ruminant, and monogastric microbiota. Consequently, highly specific carbohydrate-active enzymes, recognition proteins, and transporters are enriched in the genomes of certain species and are of critical importance in competitive environments. In Bacteroidetes bacteria, these systems are organized as polysaccharide utilization loci (PULs), which are strictly regulated, colocalized gene clusters that encode enzyme and protein ensembles required for the saccharification of complex carbohydrates. This review provides historical perspectives and summarizes key findings in the study of these systems, highlighting a critical shift from sequence-based PUL discovery to systems-based analyses combining reverse genetics, biochemistry, enzymology, and structural biology to precisely illuminate the molecular mechanisms underpinning PUL function. The ecological implications of dynamic PUL deployment by key species in the human gastrointestinal tract are explored, as well as the wider distribution of these systems in other gut, terrestrial, and marine environments.

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Glucomannan promotes Bacteroides ovatus to improve intestinal barrier function and ameliorate insulin resistance

Nie,

Sun,

et al. 2024

iMeta

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Bioactive dietary fiber has been proven to confer numerous health benefits against metabolic diseases based on the modification of gut microbiota. The metabolic protective effects of glucomannan have been previously reported in animal experiments and clinical trials. However, critical microbial signaling metabolites and the host targets associated with the metabolic benefits of glucomannan remain elusive. The results of this study revealed that glucomannan supplementation alleviated high‐fat diet (HFD)‐induced insulin resistance in mice and that its beneficial effects were dependent on the gut microbiota. Administration of glucomannan to mice promoted the growth of Bacteroides ovatus. Moreover, colonization with B. ovatus in HFD‐fed mice resulted in a decrease in insulin resistance, accompanied by improved intestinal barrier integrity and reduced systemic inflammation. Furthermore, B. ovatus‐derived indoleacetic acid (IAA) was established as a key bioactive metabolite that fortifies intestinal barrier function via activation of intestinal aryl hydrocarbon receptor (AhR), leading to an amelioration in insulin resistance. Thus, we conclude that glucomannan acts through the B. ovatus‐IAA‐intestinal AhR axis to relieve insulin resistance.

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A β‐mannan utilization locus in Bacteroides ovatus involves a GH36 α‐galactosidase active on galactomannans

Cited by 39 publications

References 42 publications

Galactomannan Catabolism Conferred by a Polysaccharide Utilization Locus of Bacteroides ovatus

Galactomannan Catabolism Conferred by a Polysaccharide Utilization Locus of Bacteroides ovatus

Polysaccharide Utilization Loci: Fueling Microbial Communities

Glucomannan promotes Bacteroides ovatus to improve intestinal barrier function and ameliorate insulin resistance

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