RadA, a MSCRAMM Adhesin of the Dominant Symbiote Ruminococcus gnavus E1, Binds Human Immunoglobulins and Intestinal Mucins.

Marc Maresca,Gwenola Simon,Ange Pujol,Cendrine Nicoletti,Thierry Giardina,Vincent Méjean,Michel Fons,Josette Perrier,Radia Alatou

doi:10.3390/biom11111613

Abstract

Adhesion to the digestive mucosa is considered a key factor for bacterial persistence within the gut. In this study, we show that Ruminococcus gnavus E1 can express the radA gene, which encodes an adhesin of the MSCRAMMs family, only when it colonizes the gut. The RadA N-terminal region contains an all-β bacterial Ig-like domain known to interact with collagens. We observed that it preferentially binds human immunoglobulins (IgA and IgG) and intestinal mucins. Using deglycosylated substrates, we also showed that the RadA N-terminal region recognizes two different types of motifs, the protein backbone of human IgG and the glycan structure of mucins. Finally, competition assays with lectins and free monosaccharides identified Galactose and N-Acetyl-Galactosamine motifs as specific targets for the binding of RadA to mucins and the surface of human epithelial cells.

Highlights

Accepted: 29 October 2021Adhesion is a general strategy developed by microorganisms to colonize complex ecosystems
Adhesion can be considered a colonization factor and an element that allows communication between the host and the microbiota. Both pathogenic and commensal bacteria have developed various adhesive structures and mechanisms to bind to the targets they are susceptible to encounter in the host
The bioinformatics gene coding for an adhesin belonging the MSCRAMMs family

Summary

Introduction

Accepted: 29 October 2021Adhesion is a general strategy developed by microorganisms to colonize complex ecosystems. Adhesion has often been considered a prerequisite for bacteria to stably persist. In their pioneer work, Gordon and co-workers illustrated the crosstalk between the host and the resident microbiota, using Bacteroides thetaiotaomicron as a model bacterium [1,2]. Adhesion can be considered a colonization factor and an element that allows communication between the host and the microbiota Both pathogenic and commensal bacteria have developed various adhesive structures and mechanisms to bind to the targets they are susceptible to encounter in the host (reviewed by Pizarro-Cerdá and Cossart [3], and Stones and Krachler [4])

Objectives

Methods

Conclusion