Back to Search
Start Over
Ascertaining the biochemical function of an essential pectin methylesterase in the gut microbe Bacteroides thetaiotaomicron
- Source :
- The Journal of Biological Chemistry
- Publication Year :
- 2020
- Publisher :
- Elsevier BV, 2020.
-
Abstract
- Pectins are a major dietary nutrient source for the human gut microbiota. The prominent gut microbe Bacteroides thetaiotaomicron was recently shown to encode the founding member (BT1017) of a new family of pectin methylesterases essential for the metabolism of the complex pectin rhamnogalacturonan-II (RG-II). However, biochemical and structural knowledge of this family is lacking. Here, we showed that BT1017 is critical for the metabolism of an RG-II–derived oligosaccharide ΔBT1017oligoB generated by a BT1017 deletion mutant (ΔBT1017) during growth on carbohydrate extract from apple juice. Structural analyses of ΔBT1017oligoB using a combination of enzymatic, mass spectrometric, and NMR approaches revealed that it is a bimethylated nonaoligosaccharide (GlcA-β1,4-(2-O-Me-Xyl-α1,3)-Fuc-α1,4-(GalA-β1,3)-Rha-α1,3-Api-β1,2-(Araf-α1,3)-(GalA-α1,4)-GalA) containing components of the RG-II backbone and its side chains. We showed that the catalytic module of BT1017 adopts an α/β-hydrolase fold, consisting of a central twisted 10-stranded β-sheet sandwiched by several α-helices. This constitutes a new fold for pectin methylesterases, which are predominantly right-handed β-helical proteins. Bioinformatic analyses revealed that the family is dominated by sequences from prominent genera of the human gut microbiota, including Bacteroides and Prevotella. Our re-sults not only highlight the critical role played by this family of enzymes in pectin metabolism but also provide new insights into the molecular basis of the adaptation of B. thetaiotaomicron to the human gut.
- Subjects :
- Models, Molecular
0301 basic medicine
food.ingredient
Pectin
Protein Conformation
microbiome
Oligosaccharides
pectin methylesterase
Crystallography, X-Ray
BT1017
Biochemistry
03 medical and health sciences
food
glycobiology
Bacterial Proteins
Prevotella
Humans
Microbiome
Molecular Biology
Phylogeny
chemistry.chemical_classification
rhamnogalacturonan II
030102 biochemistry & molecular biology
biology
Glycobiology
microbiology
Cell Biology
biology.organism_classification
Enzyme structure
enzyme structure
Gastrointestinal Microbiome
Bacteroides thetaiotaomicron
enzyme
030104 developmental biology
Enzyme
chemistry
Enzymology
Bacteroides
Carboxylic Ester Hydrolases
Subjects
Details
- ISSN :
- 00219258
- Volume :
- 295
- Database :
- OpenAIRE
- Journal :
- Journal of Biological Chemistry
- Accession number :
- edsair.doi.dedup.....30918a39ff0acb72091c7e9d1a06a4c2