Molecular Insights Into O-Linked Glycan Utilization by Gut Microbes.

Kevin J González-Morelo,Marco Vega-Sagardía,Daniel Garrido

doi:10.3389/fmicb.2020.591568

Kevin J González-Morelo, Marco Vega-Sagardía + Show 1 more

Open Access

https://doi.org/10.3389/fmicb.2020.591568

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Abstract

O-linked glycosylation is a post-translational modification found mainly in eukaryotic cells, which covalently attaches oligosaccharides to secreted proteins in certain threonine or serine residues. Most of O-glycans have N-acetylgalactosamine (GalNAc) as a common core. Several glycoproteins, such as mucins (MUCs), immunoglobulins, and caseins are examples of O-glycosylated structures. These glycans are further elongated with other monosaccharides and sulfate groups. Some of them could be found in dairy foods, while others are produced endogenously, in both cases interacting with the gut microbiota. Interestingly, certain gut microbes can access, release, and consume O-linked glycans as a carbon source. Among these, Akkermansia muciniphila, Bifidobacterium bifidum, and Bacteroides thetaiotaomicron are prominent O-linked glycan utilizers. Their consumption strategies include specialized α-fucosidases and α-sialidases, in addition to endo-α-N-acetylgalactosaminidases that release galacto-N-biose (GNB) from peptides backbones. O-linked glycan utilization by certain gut microbes represents an important niche that allows them to predominate and modulate host responses such as inflammation. Here, we focus on the distinct molecular mechanisms of consumption of O-linked GalNAc glycans by prominent gut microbes, especially from mucin and casein glycomacropeptide (GMP), highlighting the potential of these structures as emerging prebiotics.

Highlights

There is a great interest regarding the impact and modulation of the gut microbiota through our diet
These benefits include a reduced microbial load of pathogens (Gibson et al, 2005), stimulation of the immune system (Shokryazdan et al, 2017), and lower allergy rates (Brosseau et al, 2019). These effects are attributed in part to the ability of prebiotics to be fermented by healthy microorganisms and stimulate the production of certain short-chain fatty acids (SCFA), especially butyrate (Rivière et al, 2016)
This study presented important in vivo evidence linking the foraging of host-derived glycans, the action of the gut microbiota, and inflammatory bowel diseases (IBDs)

Summary

Introduction

There is a great interest regarding the impact and modulation of the gut microbiota through our diet. A recent definition of prebiotic corresponds to a substrate that is selectively utilized by host microorganisms conferring a health benefit (Gibson et al, 2017) These benefits include a reduced microbial load of pathogens (Gibson et al, 2005), stimulation of the immune system (Shokryazdan et al, 2017), and lower allergy rates (Brosseau et al, 2019). These effects are attributed in part to the ability of prebiotics to be fermented by healthy microorganisms and stimulate the production of certain short-chain fatty acids (SCFA), especially butyrate (Rivière et al, 2016). Carbohydrates such as inulin and fructo-oligosaccharides (FOS) have been studied as prebiotics (Vandeputte et al, 2017; Wilson and Whelan, 2017; BeMiller, 2019)

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