Recognition and degradation of plant cell wall polysaccharides by two human gut symbionts
| Autor: | Harry J. Gilbert, Elisabeth C. Lowe, Jeffrey I. Gordon, Nathan P. McNulty, Bernard Henrissat, Eric C. Martens, David N. Bolam, Nicholas A. Pudlo, D. Wade Abbott, Meng-Meng Wu, Herbert C. Chiang |
|---|---|
| Jazyk: | angličtina |
| Rok vydání: | 2011 |
| Předmět: |
Glycan
QH301-705.5 Polysaccharide General Biochemistry Genetics and Molecular Biology Cell wall 03 medical and health sciences Cell Wall Polysaccharides Plant Cells Bacteroides Humans Biology (General) Symbiosis Biology Gene Oligonucleotide Array Sequence Analysis 030304 developmental biology chemistry.chemical_classification Genetics 0303 health sciences General Immunology and Microbiology biology 030306 microbiology Gene Expression Profiling General Neuroscience Monosaccharides Gene Expression Regulation Bacterial biology.organism_classification Gastrointestinal Tract chemistry Biochemistry Genes Bacterial Genetic Loci Synopsis biology.protein Pectins General Agricultural and Biological Sciences Bacteroides thetaiotaomicron Bacteria Symbiotic bacteria |
| Zdroj: | PLoS Biology, Vol 9, Iss 12, p e1001221 (2011) PLoS Biology |
| ISSN: | 1545-7885 1544-9173 |
| Popis: | 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. |
| Databáze: | OpenAIRE |
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