PDBsum entry 6euf

Hydrolase

PDB id: 6euf

Contents

Protein chains

472 a.a.

Ligands

GAL-GAL-AHR-AHR-BDP ×2

GAL-GAL-BDP-RAM-AHR-AHR ×2

Waters ×538

PDB id:

6euf

Name:

Hydrolase

Title:

The gh43, beta 1,3 galactosidase, bt0265

Structure:

Beta-glucanase. Chain: a, b, c, d. Engineered: yes

Source:

Bacteroides thetaiotaomicron (strain atcc 29148 / dsm 2079 / nctc 10582 / e50 / vpi-5482). Organism_taxid: 226186. Strain: atcc 29148 / dsm 2079 / nctc 10582 / e50 / vpi-5482. Gene: bt_0265. Expressed in: escherichia coli. Expression_system_taxid: 562

Resolution:

2.20Å R-factor: 0.211 R-free: 0.271

Authors:

A.Cartmell,H.J.Gilbert

Key ref:

A.Cartmell et al. (2018). A surface endogalactanase in Bacteroides thetaiotaomicron confers keystone status for arabinogalactan degradation. Nat Microbiol, 3, 1314-1326. PubMed id: 30349080 DOI: 10.1038/s41564-018-0258-8

Date:

30-Oct-17 Release date: 17-Oct-18

Protein chains

Q8AB46  (Q8AB46_BACTN) -  Beta-glucanase from Bacteroides thetaiotaomicron (strain ATCC 29148 / DSM 2079 / JCM 5827 / CCUG 10774 / NCTC 10582 / VPI-5482 / E50)

Seq: 493 a.a.

Struc: 472 a.a.

DOI no: 10.1038/s41564-018-0258-8

Nat Microbiol 3:1314-1326 (2018)

PubMed id: 30349080

A surface endogalactanase in Bacteroides thetaiotaomicron confers keystone status for arabinogalactan degradation.

A.Cartmell, J.Muñoz-Muñoz, J.A.Briggs, D.A.Ndeh, E.C.Lowe, A.Baslé, N.Terrapon, K.Stott, T.Heunis, J.Gray, L.Yu, P.Dupree, P.Z.Fernandes, S.Shah, S.J.Williams, A.Labourel, M.Trost, B.Henrissat, H.J.Gilbert.

ABSTRACT

Glycans are major nutrients for the human gut microbiota (HGM). Arabinogalactan proteins (AGPs) comprise a heterogenous group of plant glycans in which a β1,3-galactan backbone and β1,6-galactan side chains are conserved. Diversity is provided by the variable nature of the sugars that decorate the galactans. The mechanisms by which nutritionally relevant AGPs are degraded in the HGM are poorly understood. Here we explore how the HGM organism Bacteroides thetaiotaomicron metabolizes AGPs. We propose a sequential degradative model in which exo-acting glycoside hydrolase (GH) family 43 β1,3-galactanases release the side chains. These oligosaccharide side chains are depolymerized by the synergistic action of exo-acting enzymes in which catalytic interactions are dependent on whether degradation is initiated by a lyase or GH. We identified two GHs that establish two previously undiscovered GH families. The crystal structures of the exo-β1,3-galactanases identified a key specificity determinant and departure from the canonical catalytic apparatus of GH43 enzymes. Growth studies of Bacteroidetes spp. on complex AGP revealed 3 keystone organisms that facilitated utilization of the glycan by 17 recipient bacteria, which included B. thetaiotaomicron. A surface endo-β1,3-galactanase, when engineered into B. thetaiotaomicron, enabled the bacterium to utilize complex AGPs and act as a keystone organism.