Dietary pectic glycans are degraded by coordinated enzyme pathways in human colonic Bacteroides



Luis, Ana S, Briggs, Jonathon, Zhang, Xiaoyang, Farnell, Benjamin, Ndeh, Didier, Labourel, Aurore, Basle, Arnaud, Cartmell, Alan ORCID: 0000-0002-5512-249X, Terrapon, Nicolas, Stott, Katherine
et al (show 11 more authors) (2018) Dietary pectic glycans are degraded by coordinated enzyme pathways in human colonic Bacteroides. Nature Microbiology, 3 (2). 210 - 219.

Access the full-text of this item by clicking on the Open Access link.

Abstract

The major nutrients available to human colonic Bacteroides species are glycans, exemplified by pectins, a network of covalently linked plant cell wall polysaccharides containing galacturonic acid (GalA). Metabolism of complex carbohydrates by the Bacteroides genus is orchestrated by polysaccharide utilization loci (PULs). In Bacteroides thetaiotaomicron, a human colonic bacterium, the PULs activated by different pectin domains have been identified; however, the mechanism by which these loci contribute to the degradation of these GalA-containing polysaccharides is poorly understood. Here we show that each PUL orchestrates the metabolism of specific pectin molecules, recruiting enzymes from two previously unknown glycoside hydrolase families. The apparatus that depolymerizes the backbone of rhamnogalacturonan-I is particularly complex. This system contains several glycoside hydrolases that trim the remnants of other pectin domains attached to rhamnogalacturonan-I, and nine enzymes that contribute to the degradation of the backbone that makes up a rhamnose-GalA repeating unit. The catalytic properties of the pectin-degrading enzymes are optimized to protect the glycan cues that activate the specific PULs ensuring a continuous supply of inducing molecules throughout growth. The contribution of Bacteroides spp. to metabolism of the pectic network is illustrated by cross-feeding between organisms.

Item Type: Article
Depositing User: Symplectic Admin
Date Deposited: 10 Sep 2019 16:05
Last Modified: 19 Oct 2021 16:10
DOI: 10.1038/s41564-017-0079-1
Open Access URL: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC57848...
Related URLs:
URI: https://livrepository.liverpool.ac.uk/id/eprint/3054140