Transcription analysis of wild-type and chuR Bacteroides thetaiotaomicron genes in the mouse cecum

ABSTRACT: The large-scale application of genomic and metagenomic sequencing technologies has yielded a number of insights about the metabolic potential of symbiotic human gut microbes. Bacteria that colonize the mucosal layer that overlies the gut epithelium have access to highly-sulfated polysaccharides (i.e., mucin oligosaccharides and glycosaminoglycans), which they could potentially forage as nutrient sources. To be active, sulfatases must undergo a critical post-translational modification catalyzed in anaerobic bacteria by the AdoMet enzyme anSME (anaerobic Sulfatase-Maturating Enzyme). In the present study, we have tested the role of this pathway in the prominent gut symbiont Bacteroides thetaiotaomicron, which possesses more predicted sulfatases (28) than in the human genome and a single predicted anSME. In vitro studies revealed that deletion of its anSME (BT0238) results in loss of sulfatase activity and impaired ability to use sulfated polysaccharides as carbon sources. Co-colonization of germ-free animals with both isogenic strains, or invasion experiments involving the introduction of one then the other strain, established that anSME activity and the sulfatases that are activated via this pathway, are important fitness factors for B. thetaiotaomicron, especially when mice are fed a simple sugar diet that requires this saccharolytic bacterium to adaptively forage on host glycans as nutrients. Whole genome transcriptional profiling of wild-type and the anSME mutant in vivo revealed that loss of this enzyme alters expression of genes involved in mucin utilization and that this disrupted ability to access mucosal glycans likely underlies the observed dramatic colonization defect. Comparative genomic analysis reveals that 100% of 46 fully sequenced human gut Bacteroidetes contain homologs of BT0238 and genes encoding sulfatases, suggesting that this is an important and evolutionarily conserved feature. Three replicate samples from 4 different biological treatment groups: 1. Wild-type B. thetaiotaomicron from the cecum of gnotobiotic mice fed a simple-sugar diet; 2. chuR mutant B. thetaiotaomicron from the cecum of gnotobiotic mice fed a simple-sugar diet; 3. Wild-type B. thetaiotaomicron from the cecum of gnotobiotic mice fed a plant-rich diet; 4. chuR mutant B. thetaiotaomicron from the cecum of gnotobiotic mice fed a plant-rich diet.

ORGANISM(S): Bacteroides thetaiotaomicron

SUBMITTER: Eric Martens 

PROVIDER: E-GEOD-25415 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress