6E9B

Bacteroides ovatus mixed-linkage glucan utilization locus (MLGUL) SGBP-B in complex with mixed-linkage heptasaccharide

Summary for 6E9B

• Entry DOI: 10.2210/pdb6e9b/pdb
• Descriptor: Mixed-linkage glucan utilization locus (MLGUL) SGBP-B, beta-D-glucopyranose-(1-4)-beta-D-glucopyranose-(1-3)-beta-D-glucopyranose-(1-4)-beta-D-glucopyranose-(1-4)-beta-D-glucopyranose-(1-4)-beta-D-glucopyranose-(1-3)-beta-D-glucopyranose, SULFATE ION, ... (4 entities in total)
• Functional Keywords: tetratricopeptide repeat, outer membrane protein, binding protein, sugar binding protein
• Biological source: Bacteroides ovatus (strain ATCC 8483 / DSM 1896 / JCM 5824 / NCTC 11153)
• Total number of polymer chains: 4
• Total formula weight: 184826.94

Authors

Tamura, K.,Gardill, B.R.,Brumer, H.,Van Petegem, F. (deposition date: 2018-07-31, release date: 2019-05-15, Last modification date: 2023-10-11)

Primary citation

Tamura, K.,Foley, M.H.,Gardill, B.R.,Dejean, G.,Schnizlein, M.,Bahr, C.M.E.,Louise Creagh, A.,van Petegem, F.,Koropatkin, N.M.,Brumer, H.
Surface glycan-binding proteins are essential for cereal beta-glucan utilization by the human gut symbiont Bacteroides ovatus.
Cell.Mol.Life Sci., 76:4319-4340, 2019

PubMed Abstract: The human gut microbiota, which underpins nutrition and systemic health, is compositionally sensitive to the availability of complex carbohydrates in the diet. The Bacteroidetes comprise a dominant phylum in the human gut microbiota whose members thrive on dietary and endogenous glycans by employing a diversity of highly specific, multi-gene polysaccharide utilization loci (PUL), which encode a variety of carbohydrases, transporters, and sensor/regulators. PULs invariably also encode surface glycan-binding proteins (SGBPs) that play a central role in saccharide capture at the outer membrane. Here, we present combined biophysical, structural, and in vivo characterization of the two SGBPs encoded by the Bacteroides ovatus mixed-linkage β-glucan utilization locus (MLGUL), thereby elucidating their key roles in the metabolism of this ubiquitous dietary cereal polysaccharide. In particular, molecular insight gained through several crystallographic complexes of SGBP-A and SGBP-B with oligosaccharides reveals that unique shape complementarity of binding platforms underpins specificity for the kinked MLG backbone vis-à-vis linear β-glucans. Reverse-genetic analysis revealed that both the presence and binding ability of the SusD homolog BoSGBP-A are essential for growth on MLG, whereas the divergent, multi-domain BoSGBP-B is dispensable but may assist in oligosaccharide scavenging from the environment. The synthesis of these data illuminates the critical role SGBPs play in concert with other MLGUL components, reveals new structure-function relationships among SGBPs, and provides fundamental knowledge to inform future (meta)genomic, biochemical, and microbiological analyses of the human gut microbiota.

PubMed: 31062073
DOI: 10.1007/s00018-019-03115-3

Experimental method

X-RAY DIFFRACTION (3.15 Å)