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Recognition and Degradation of Plant Cell Wall Polysaccharides by Two Human Gut Symbionts
Symbiotic bacteria inhabiting the human gut have evolved under intense pressure to utilize complex carbohydrates, primarily plant cell wall glycans in our diets. These polysaccharides are not digested by human enzymes, but are processed to absorbable short chain fatty acids by gut bacteria. The Bact...
Autores principales: | , , , , , , , , , , |
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Formato: | Online Artículo Texto |
Lenguaje: | English |
Publicado: |
Public Library of Science
2011
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Materias: | |
Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3243724/ https://www.ncbi.nlm.nih.gov/pubmed/22205877 http://dx.doi.org/10.1371/journal.pbio.1001221 |
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author | Martens, Eric C. Lowe, Elisabeth C. Chiang, Herbert Pudlo, Nicholas A. Wu, Meng McNulty, Nathan P. Abbott, D. Wade Henrissat, Bernard Gilbert, Harry J. Bolam, David N. Gordon, Jeffrey I. |
author_facet | Martens, Eric C. Lowe, Elisabeth C. Chiang, Herbert Pudlo, Nicholas A. Wu, Meng McNulty, Nathan P. Abbott, D. Wade Henrissat, Bernard Gilbert, Harry J. Bolam, David N. Gordon, Jeffrey I. |
author_sort | Martens, Eric C. |
collection | PubMed |
description | Symbiotic bacteria inhabiting the human gut have evolved under intense pressure to utilize complex carbohydrates, primarily plant cell wall glycans in our diets. These polysaccharides are not digested by human enzymes, but are processed to absorbable short chain fatty acids by gut bacteria. The Bacteroidetes, one of two dominant bacterial phyla in the adult gut, possess broad glycan-degrading abilities. These species use a series of membrane protein complexes, termed Sus-like systems, for catabolism of many complex carbohydrates. However, the role of these systems in degrading the chemically diverse repertoire of plant cell wall glycans remains unknown. Here we show that two closely related human gut Bacteroides, B. thetaiotaomicron and B. ovatus, are capable of utilizing nearly all of the major plant and host glycans, including rhamnogalacturonan II, a highly complex polymer thought to be recalcitrant to microbial degradation. Transcriptional profiling and gene inactivation experiments revealed the identity and specificity of the polysaccharide utilization loci (PULs) that encode individual Sus-like systems that target various plant polysaccharides. Comparative genomic analysis indicated that B. ovatus possesses several unique PULs that enable degradation of hemicellulosic polysaccharides, a phenotype absent from B. thetaiotaomicron. In contrast, the B. thetaiotaomicron genome has been shaped by increased numbers of PULs involved in metabolism of host mucin O-glycans, a phenotype that is undetectable in B. ovatus. Binding studies of the purified sensor domains of PUL-associated hybrid two-component systems in conjunction with transcriptional analyses demonstrate that complex oligosaccharides provide the regulatory cues that induce PUL activation and that each PUL is highly specific for a defined cell wall polymer. These results provide a view of how these species have diverged into different carbohydrate niches by evolving genes that target unique suites of available polysaccharides, a theme that likely applies to disparate bacteria from the gut and other habitats. |
format | Online Article Text |
id | pubmed-3243724 |
institution | National Center for Biotechnology Information |
language | English |
publishDate | 2011 |
publisher | Public Library of Science |
record_format | MEDLINE/PubMed |
spelling | pubmed-32437242011-12-28 Recognition and Degradation of Plant Cell Wall Polysaccharides by Two Human Gut Symbionts Martens, Eric C. Lowe, Elisabeth C. Chiang, Herbert Pudlo, Nicholas A. Wu, Meng McNulty, Nathan P. Abbott, D. Wade Henrissat, Bernard Gilbert, Harry J. Bolam, David N. Gordon, Jeffrey I. PLoS Biol Research Article Symbiotic bacteria inhabiting the human gut have evolved under intense pressure to utilize complex carbohydrates, primarily plant cell wall glycans in our diets. These polysaccharides are not digested by human enzymes, but are processed to absorbable short chain fatty acids by gut bacteria. The Bacteroidetes, one of two dominant bacterial phyla in the adult gut, possess broad glycan-degrading abilities. These species use a series of membrane protein complexes, termed Sus-like systems, for catabolism of many complex carbohydrates. However, the role of these systems in degrading the chemically diverse repertoire of plant cell wall glycans remains unknown. Here we show that two closely related human gut Bacteroides, B. thetaiotaomicron and B. ovatus, are capable of utilizing nearly all of the major plant and host glycans, including rhamnogalacturonan II, a highly complex polymer thought to be recalcitrant to microbial degradation. Transcriptional profiling and gene inactivation experiments revealed the identity and specificity of the polysaccharide utilization loci (PULs) that encode individual Sus-like systems that target various plant polysaccharides. Comparative genomic analysis indicated that B. ovatus possesses several unique PULs that enable degradation of hemicellulosic polysaccharides, a phenotype absent from B. thetaiotaomicron. In contrast, the B. thetaiotaomicron genome has been shaped by increased numbers of PULs involved in metabolism of host mucin O-glycans, a phenotype that is undetectable in B. ovatus. Binding studies of the purified sensor domains of PUL-associated hybrid two-component systems in conjunction with transcriptional analyses demonstrate that complex oligosaccharides provide the regulatory cues that induce PUL activation and that each PUL is highly specific for a defined cell wall polymer. These results provide a view of how these species have diverged into different carbohydrate niches by evolving genes that target unique suites of available polysaccharides, a theme that likely applies to disparate bacteria from the gut and other habitats. Public Library of Science 2011-12-20 /pmc/articles/PMC3243724/ /pubmed/22205877 http://dx.doi.org/10.1371/journal.pbio.1001221 Text en Martens et al. http://creativecommons.org/licenses/by/4.0/ This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are properly credited. |
spellingShingle | Research Article Martens, Eric C. Lowe, Elisabeth C. Chiang, Herbert Pudlo, Nicholas A. Wu, Meng McNulty, Nathan P. Abbott, D. Wade Henrissat, Bernard Gilbert, Harry J. Bolam, David N. Gordon, Jeffrey I. Recognition and Degradation of Plant Cell Wall Polysaccharides by Two Human Gut Symbionts |
title | Recognition and Degradation of Plant Cell Wall Polysaccharides by Two Human Gut Symbionts |
title_full | Recognition and Degradation of Plant Cell Wall Polysaccharides by Two Human Gut Symbionts |
title_fullStr | Recognition and Degradation of Plant Cell Wall Polysaccharides by Two Human Gut Symbionts |
title_full_unstemmed | Recognition and Degradation of Plant Cell Wall Polysaccharides by Two Human Gut Symbionts |
title_short | Recognition and Degradation of Plant Cell Wall Polysaccharides by Two Human Gut Symbionts |
title_sort | recognition and degradation of plant cell wall polysaccharides by two human gut symbionts |
topic | Research Article |
url | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3243724/ https://www.ncbi.nlm.nih.gov/pubmed/22205877 http://dx.doi.org/10.1371/journal.pbio.1001221 |
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