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Dietary sugar silences a colonization factor in a mammalian gut symbiont.

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PubMed ID: 30559205

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Townsend GE, Han W, Schwalm ND, Raghavan V, Barry NA, Goodman AL, Groisman EA

Proc Natl Acad Sci U S A. Jan 2019. doi: 10.1073/pnas.1813780115

COMMENT: This work is focused on how fructose and sucrose impact the colonization of the gut microbiome by Bacteroides thetaiotaomicron, a commensal bacteria abundant in healthy gut human microbiomes. Surprisingly the authors find, based on experiments in mice, that fructose and sucrose are able to silence a critical colonization factor of B. thetaiotaomicron, called Roc.

OBJECTIVES:

Given the alarming increase in consumption of fructose and sucrose (a heterodimer of glucose and fructose) by Western populations, we wondered how these simple sugars impact colonization by Bacteroides thetaiotaomicron, a member of the gut microbiota associated with lean and healthy individuals

MAIN RESULTS:

We report that dietary glucose and sucrose silence Roc expression and that Roc is dispensable for utilization of glucose and sucrose-derived fructose. We establish that the mRNA leader preceding the roc-coding region is necessary and sufficient for Roc silencing by fructose and glucose. Furthermore, we engineered a strain that is refractory to silencing by these simple sugars and demonstrate that the engineered strain outcompetes wild-type B. thetaiotaomicron in mice fed glucose and sucrose. Our findings demonstrate how dietary simple sugars can suppress gut colonization in a commensal bacterium just by altering the levels of a colonization factor dispensable for the utilization of such sugars

CONCLUSIONS:

Our findings reveal how common dietary additives endemic to Western human populations can impact gut colonization by the microbiota independently of their ability to serve as nutrients. We establish that fructose and glucose silence a critical colonization factor, called Roc, in a widely distributed gut commensal bacterium B. thetaiotaomicron. Furthermore, we demonstrate that fructo-oligosaccharides, which are used as prebiotics in humans, fail to silence Roc, indicating that the presence of monomeric fructose is required for this effect. Additionally, we determine that a short 5′ mRNA leader is necessary and sufficient for the silencing effects that fructose and glucose exert on the amounts of the associated coding region. The identified mRNA leader may be used to engineer gut microbes to alter their behaviors in response to dietary components.

 

Contributor

Raquel Tobes