Phage-encoded carbohydrate-interacting proteins in the human gut

Abstract

In the human gastrointestinal tract, the gut mucosa and the bacterial component of the microbiota interact and modulate each other to accomplish a variety of critical functions. These include digestion aid, maintenance of the mucosal barrier, immune regulation, and production of vitamins, hormones, and other metabolites that are important for our health. The mucus lining of the gut is primarily composed of mucins, large glycosylated proteins with glycosylation patterns that vary depending on factors including location in the digestive tract and the local microbial population. Many gut bacteria have evolved to reside within the mucus layer and thus encode mucus-adhering and -degrading proteins. By doing so, they can influence the integrity of the mucus barrier and therefore promote either health maintenance or the onset and progression of some diseases. The viral members of the gut – mostly composed of bacteriophages – have also been shown to have mucus-interacting capabilities, but their mechanisms and effects remain largely unexplored. In this review, we discuss the role of bacteriophages in influencing mucosal integrity, indirectly via interactions with other members of the gut microbiota, or directly with the gut mucus via phage-encoded carbohydrate-interacting proteins. We additionally discuss how these phage-mucus interactions may influence health and disease states.

An extended catalog of integrated prophages in the infant and adult fecal microbiome shows high prevalence of lysogeny

“…Importantly, pAMGs encoding glycosides hydrolases were previously reported in adult gut viromes ( Shaffer et al, 2020 ) and in soil, where the functionality of a GH5 pAMG was experimentally verified ( Trubl et al, 2018 ). Importantly, the functional role of these glycoside hydrolases has been suggested to include also adhesion of the virion to bacterial cells or host-associated mucosal glycans ( Benler et al, 2021 ; Rothschild-Rodriguez et al, 2023 ). We also detected the presence of phage encoded glycosyltransferases from the GT2 family that has been shown to be able to confer protection to phage infection by modifying the bacterial capsule polysaccharide structure ( Porter et al, 2020 ).…”

Mucin and Agitation Shape Predation of Escherichia coli by Lytic Coliphage

“…Concepts of bacterial motility, phage diffusion, and mucin concentration were recently reviewed [ 29 ], and if bacterial motility was the only determining factor for successful phage predation, it would be expected that predation would decrease as motility was lost within increasing mucin concentrations. This is not what the static, in-tube assays showed.…”

“…Given that bacteria are known to adhere to mucin [ 24 ] and phages also have affinity with accumulation in mucosal secretions [ 9 , 25 , 26 ] it is unsurprising that there are several reports of phage–bacteria interactions influenced by their surrounding mucin micro-environment [ 26 , 27 , 28 ]. The nature and consequences of bacteria and phage interactions with mucin was recently reviewed by Rothschild-Rodriguez et al [ 29 ]. Agitation could further affect these interactions through its impact on mucin.…”