PDBsum entry 4mt5

Protein binding

PDB id: 4mt5

Contents

Protein chains

184 a.a.

Waters ×146

PDB id:

4mt5

Name:

Protein binding

Title:

Crystal structure of mub-rv

Structure:

Mucus binding proteinn. Chain: a, b. Fragment: mub repeat v (unp residues 1612-1794. Engineered: yes

Source:

Lactobacillus reuteri. Organism_taxid: 927703. Strain: atcc 53608. Gene: mub. Expressed in: escherichia coli. Expression_system_taxid: 562.

Resolution:

2.60Å R-factor: 0.214 R-free: 0.269

Authors:

S.Etzold,N.Juge,A.M.Hemmings

Key ref:

S.Etzold et al. (2014). Structural basis for adaptation of lactobacilli to gastrointestinal mucus. Environ Microbiol, 16, 888-903. PubMed id: 24373178 DOI: 10.1111/1462-2920.12377

Date:

19-Sep-13 Release date: 06-Aug-14

Protein chains

F8KCE4  (F8KCE4_LIMR5) -  Putative mucin binding protein from Limosilactobacillus reuteri subsp. suis (strain ATCC 53608 / LMG 31752 / 1063)

Seq: 2082 a.a.

Struc: 184 a.a.*

* PDB and UniProt seqs differ at 1 residue position (black cross)

DOI no: 10.1111/1462-2920.12377

Environ Microbiol 16:888-903 (2014)

PubMed id: 24373178

Structural basis for adaptation of lactobacilli to gastrointestinal mucus.

S.Etzold, O.I.Kober, D.A.Mackenzie, L.E.Tailford, A.P.Gunning, J.Walshaw, A.M.Hemmings, N.Juge.

ABSTRACT

The mucus layer covering the gastrointestinal (GI) epithelium is critical in selecting and maintaining homeostatic interactions with our gut bacteria. However, the underpinning mechanisms of these interactions are not understood. Here, we provide structural and functional insights into the canonical mucus-binding protein (MUB), a multi-repeat cell-surface adhesin found in Lactobacillus inhabitants of the GI tract. X-ray crystallography together with small-angle X-ray scattering demonstrated a 'beads on a string' arrangement of repeats, generating 174 nm long protein fibrils, as shown by atomic force microscopy. Each repeat consists of tandemly arranged Ig- and mucin-binding protein (MucBP) modules. The binding of full-length MUB was confined to mucus via multiple interactions involving terminal sialylated mucin glycans. While individual MUB domains showed structural similarity to fimbrial proteins from Gram-positive pathogens, the particular organization of MUB provides a structural explanation for the mechanisms in which lactobacilli have adapted to their host niche by maximizing interactions with the mucus receptors, potentiating the retention of bacteria within the mucus layer. Together, this study reveals functional and structural features which may affect tropism of microbes across mucus and along the GI tract, providing unique insights into the mechanisms adopted by commensals and probiotics to adapt to the mucosal environment.