Glycan Utilization Strategy of the Butyrate Producing Gut Symbiont Roseburia intestinalis

Research output: Book/ReportPh.D. thesisResearch

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Abstract

The human gut microbiota’s (HGM’s) interplay with the host and diet exerts a profound impact on our health. Dietary fibers, which are fermented to short chain fatty acids (SCFAs), are key in shaping the composition and the metabolic output of the HGM. The SCFA butyrate, produced mainly by Clostridium XIVa Firmicutes modulates host immune homeostasis and confers protection from inflammatory disorders and colorectal cancer. Despite this vital role on human health, the mechanisms underpinning the utilization of dietary fibers by butyrate producers are largely unexplored. This thesis aims at bringing insight into this facet using the abundant and prevalent butyrogenic bacterium Roseburia intestinalis as a model system .
The major dietary fiber xylan is shown to be an excellent substrate for R. intestinalis
in this work. Transcriptomic analysis identified the molecular apparatus that confers growth on xylan, including a key cell-attached modular xylanase of glycoside hydrolase family 10 (GH10). This enzyme harbor a new low affinity xylan binding module, which showed an atypical architecture, featuring an open and shallow binding site with a few polar contacts to a single xylosyl unit. Investigation of transport and intracellular hydrolysis outlined a model for xylan breakdown to monosaccharides. An ATP-binding cassette (ABC) transporter with preference for 4-5 xylosyl units creates a competitive window that enables R. intestinalis to co-grow with key primary xylan degraders from the Bacteroides genus, which possess an uptake preference for larger ligands.
R. intestinalis uses a similar approach, as described above, to capture, degrade and transport complex dietary β-mannans. Capture and depolymerisation of mannan is initiated by a modular GH26 mannanase and the mannan-oligosaccharides are subsequently imported into the cell for further hydrolysis using an ABC uptake system. An in vivo experiment in mice colonized by a mock community of human commensals showed that β-mannan boosts commensal mannan degraders, including R. intestinalis .


Altogether, this project highlights the differentiation of capture and transport preferences of primary glycan degraders using xylan as a model. It provides a potential strategy for promotion of key members of a healthy HGM, by designing prebiotics that selectively target specific health promoting taxonomic groups.
Original languageEnglish
Place of PublicationKgs. Lyngby, Denmark
PublisherTechnical University of Denmark
Number of pages189
Publication statusPublished - 2019

Cite this

Leth, Maria Louise. / Glycan Utilization Strategy of the Butyrate Producing Gut Symbiont Roseburia intestinalis. Kgs. Lyngby, Denmark : Technical University of Denmark, 2019. 189 p.
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Glycan Utilization Strategy of the Butyrate Producing Gut Symbiont Roseburia intestinalis. / Leth, Maria Louise.

Kgs. Lyngby, Denmark : Technical University of Denmark, 2019. 189 p.

Research output: Book/ReportPh.D. thesisResearch

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T1 - Glycan Utilization Strategy of the Butyrate Producing Gut Symbiont Roseburia intestinalis

AU - Leth, Maria Louise

PY - 2019

Y1 - 2019

N2 - The human gut microbiota’s (HGM’s) interplay with the host and diet exerts a profound impact on our health. Dietary fibers, which are fermented to short chain fatty acids (SCFAs), are key in shaping the composition and the metabolic output of the HGM. The SCFA butyrate, produced mainly by Clostridium XIVa Firmicutes modulates host immune homeostasis and confers protection from inflammatory disorders and colorectal cancer. Despite this vital role on human health, the mechanisms underpinning the utilization of dietary fibers by butyrate producers are largely unexplored. This thesis aims at bringing insight into this facet using the abundant and prevalent butyrogenic bacterium Roseburia intestinalis as a model system . The major dietary fiber xylan is shown to be an excellent substrate for R. intestinalis in this work. Transcriptomic analysis identified the molecular apparatus that confers growth on xylan, including a key cell-attached modular xylanase of glycoside hydrolase family 10 (GH10). This enzyme harbor a new low affinity xylan binding module, which showed an atypical architecture, featuring an open and shallow binding site with a few polar contacts to a single xylosyl unit. Investigation of transport and intracellular hydrolysis outlined a model for xylan breakdown to monosaccharides. An ATP-binding cassette (ABC) transporter with preference for 4-5 xylosyl units creates a competitive window that enables R. intestinalis to co-grow with key primary xylan degraders from the Bacteroides genus, which possess an uptake preference for larger ligands. R. intestinalis uses a similar approach, as described above, to capture, degrade and transport complex dietary β-mannans. Capture and depolymerisation of mannan is initiated by a modular GH26 mannanase and the mannan-oligosaccharides are subsequently imported into the cell for further hydrolysis using an ABC uptake system. An in vivo experiment in mice colonized by a mock community of human commensals showed that β-mannan boosts commensal mannan degraders, including R. intestinalis . Altogether, this project highlights the differentiation of capture and transport preferences of primary glycan degraders using xylan as a model. It provides a potential strategy for promotion of key members of a healthy HGM, by designing prebiotics that selectively target specific health promoting taxonomic groups.

AB - The human gut microbiota’s (HGM’s) interplay with the host and diet exerts a profound impact on our health. Dietary fibers, which are fermented to short chain fatty acids (SCFAs), are key in shaping the composition and the metabolic output of the HGM. The SCFA butyrate, produced mainly by Clostridium XIVa Firmicutes modulates host immune homeostasis and confers protection from inflammatory disorders and colorectal cancer. Despite this vital role on human health, the mechanisms underpinning the utilization of dietary fibers by butyrate producers are largely unexplored. This thesis aims at bringing insight into this facet using the abundant and prevalent butyrogenic bacterium Roseburia intestinalis as a model system . The major dietary fiber xylan is shown to be an excellent substrate for R. intestinalis in this work. Transcriptomic analysis identified the molecular apparatus that confers growth on xylan, including a key cell-attached modular xylanase of glycoside hydrolase family 10 (GH10). This enzyme harbor a new low affinity xylan binding module, which showed an atypical architecture, featuring an open and shallow binding site with a few polar contacts to a single xylosyl unit. Investigation of transport and intracellular hydrolysis outlined a model for xylan breakdown to monosaccharides. An ATP-binding cassette (ABC) transporter with preference for 4-5 xylosyl units creates a competitive window that enables R. intestinalis to co-grow with key primary xylan degraders from the Bacteroides genus, which possess an uptake preference for larger ligands. R. intestinalis uses a similar approach, as described above, to capture, degrade and transport complex dietary β-mannans. Capture and depolymerisation of mannan is initiated by a modular GH26 mannanase and the mannan-oligosaccharides are subsequently imported into the cell for further hydrolysis using an ABC uptake system. An in vivo experiment in mice colonized by a mock community of human commensals showed that β-mannan boosts commensal mannan degraders, including R. intestinalis . Altogether, this project highlights the differentiation of capture and transport preferences of primary glycan degraders using xylan as a model. It provides a potential strategy for promotion of key members of a healthy HGM, by designing prebiotics that selectively target specific health promoting taxonomic groups.

M3 - Ph.D. thesis

BT - Glycan Utilization Strategy of the Butyrate Producing Gut Symbiont Roseburia intestinalis

PB - Technical University of Denmark

CY - Kgs. Lyngby, Denmark

ER -

Leth ML. Glycan Utilization Strategy of the Butyrate Producing Gut Symbiont Roseburia intestinalis. Kgs. Lyngby, Denmark: Technical University of Denmark, 2019. 189 p.