Use of Atomic Force Microscopy to Study the Multi-Modular Interaction of Bacterial Adhesins to Mucins

The mucus layer covering the gastrointestinal (GI) epithelium is critical in selecting and maintaining homeostatic interactions with our gut bacteria. However, the molecular details of these interactions are not well understood. Here, we provide mechanistic insights into the adhesion properties of t...

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Bibliographic Details
Published in:International journal of molecular sciences Vol. 17; no. 11; p. 1854
Main Authors: Gunning, A., Kavanaugh, Devon, Thursby, Elizabeth, Etzold, Sabrina, MacKenzie, Donald, Juge, Nathalie
Format: Journal Article
Language:English
Published: Switzerland MDPI AG 08.11.2016
MDPI
Subjects:
Adhesins, Bacterial - chemistry
Adhesins, Bacterial - isolation & purification
Adhesins, Bacterial - metabolism
Animals
Bacteria
Bacterial Adhesion
Binding sites
Cell adhesion & migration
Culture Media, Conditioned - chemistry
Galectin 3 - chemistry
Galectin 3 - genetics
Galectin 3 - metabolism
Gene Expression
Humans
Intestinal Mucosa - chemistry
Lactobacillus
Limosilactobacillus reuteri - growth & development
Limosilactobacillus reuteri - metabolism
Microscopy
Microscopy, Atomic Force
Models, Molecular
Mucin-3 - chemistry
Mucin-3 - isolation & purification
Mucin-3 - metabolism
Protein Binding
Proteins
Recombinant Proteins - chemistry
Recombinant Proteins - genetics
Recombinant Proteins - metabolism
Swine
intestinal mucin
Lactobacillus reuteri
single molecule force spectroscopy
bacterial adhesins
mucus binding protein
atomic force microscopy
gut microbiota
ISSN:1422-0067, 1661-6596, 1422-0067
Online Access:Get full text
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Summary:The mucus layer covering the gastrointestinal (GI) epithelium is critical in selecting and maintaining homeostatic interactions with our gut bacteria. However, the molecular details of these interactions are not well understood. Here, we provide mechanistic insights into the adhesion properties of the canonical mucus-binding protein (MUB), a large multi-repeat cell–surface adhesin found in Lactobacillus inhabiting the GI tract. We used atomic force microscopy to unravel the mechanism driving MUB-mediated adhesion to mucins. Using single-molecule force spectroscopy we showed that MUB displayed remarkable adhesive properties favouring a nanospring-like adhesion model between MUB and mucin mediated by unfolding of the multiple repeats constituting the adhesin. We obtained direct evidence for MUB self-interaction; MUB–MUB followed a similar binding pattern, confirming that MUB modular structure mediated such mechanism. This was in marked contrast with the mucin adhesion behaviour presented by Galectin-3 (Gal-3), a mammalian lectin characterised by a single carbohydrate binding domain (CRD). The binding mechanisms reported here perfectly match the particular structural organization of MUB, which maximizes interactions with the mucin glycan receptors through its long and linear multi-repeat structure, potentiating the retention of bacteria within the outer mucus layer.
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ISSN:1422-0067
1661-6596
1422-0067
DOI:10.3390/ijms17111854