The mucin-degradation strategy of Ruminococcus gnavus: The importance of intramolecular trans-sialidases

Emmanuelle H Crost,Louise E Tailford,Marie Monestier,David Swarbreck,Bernard Henrissat,Lisa C Crossman,Nathalie Juge

doi:10.1080/19490976.2016.1186334

Abstract

ABSTRACTWe previously identified and characterized an intramolecular trans-sialidase (IT-sialidase) in the gut symbiont Ruminococcus gnavus ATCC 29149, which is associated to the ability of the strain to grow on mucins. In this work we have obtained and analyzed the draft genome sequence of another R. gnavus mucin-degrader, ATCC 35913, isolated from a healthy individual. Transcriptomics analyses of both ATCC 29149 and ATCC 35913 strains confirmed that the strategy utilized by R. gnavus for mucin-degradation is focused on the utilization of terminal mucin glycans. R. gnavus ATCC 35913 also encodes a predicted IT-sialidase and harbors a Nan cluster dedicated to sialic acid utilization. We showed that the Nan cluster was upregulated when the strains were grown in presence of mucin. In addition we demonstrated that both R. gnavus strains were able to grow on 2,7-anyhydro-Neu5Ac, the IT-sialidase transglycosylation product, as a sole carbon source. Taken together these data further support the hypothesis that IT-sialidase expressing gut microbes, provide commensal bacteria such as R. gnavus with a nutritional competitive advantage, by accessing and transforming a source of nutrient to their own benefit.

Highlights

The gastrointestinal (GI) tract is inhabited by a diverse microbial community that influences host health through a number of mechanisms, including the production of metabolites, protection against pathogens, and interactions with the host immune system and physiology
We tested the ability of R. gnavus ATCC 35913 to grow on mucin using purified porcine gastric mucin as source of carbon
As previously reported for R. gnavus ATCC 29149,10 R. gnavus ATCC 35913 grew on Glc and on 30-sialyllactose (Neu5Aca2–3Galb1–4Glc, 30SL) but was unable to grow in presence of sialic acid (Neu5Ac) or 60-sialyllactose (Neu5Aca2–6Galb1–4Glc, 60SL) as sole carbon source (Table 1)

Summary

Introduction

The gastrointestinal (GI) tract is inhabited by a diverse microbial community (microbiota) that influences host health through a number of mechanisms, including the production of metabolites, protection against pathogens, and interactions with the host immune system and physiology.

Results

Conclusion