The molecular basis of cereal mixed-linkage β-glucan utilization by the human gut bacterium Segatella copri

• Published in: The Journal of biological chemistry Vol. 300; no. 9; p. 107625
• Main Authors: Golisch, Benedikt, Cordeiro, Rosa Lorizolla, Fraser, Alexander S.C., Briggs, Jonathon, Stewart, William A., Van Petegem, Filip, Brumer, Harry
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01.09.2024; Elsevier; American Society for Biochemistry and Molecular Biology
• Subjects: glycan-binding protein; glycoside hydrolase; human gut microbiota; microbiome; TonB-dependent transporter; BCA; TonB-dependent transporter; IMAC; SGBP; CAZyme; GM; PUL; HEC; Hepes; XyG; human gut microbiota; MLG; HPAEC-PAD; microbiome; HGM; glycan-binding protein; BSA; glycoside hydrolase; pNP; ITC; TBDT; HTCS; AGE
• ISSN: 0021-9258; 1083-351X; 1083-351X
• DOI: 10.1016/j.jbc.2024.107625

Mixed-linkage β(1,3)/β(1,4)-glucan (MLG) is abundant in the human diet through the ingestion of cereal grains and is widely associated with healthful effects on metabolism and cholesterol levels. MLG is also a major source of fermentable glucose for the human gut microbiota (HGM). Bacteria from the family Prevotellaceae are highly represented in the HGM of individuals who eat plant-rich diets, including certain indigenous people and vegetarians in postindustrial societies. Here, we have defined and functionally characterized an exemplar Prevotellaceae MLG polysaccharide utilization locus (MLG-PUL) in the type-strain Segatella copri (syn. Prevotella copri) DSM 18205 through transcriptomic, biochemical, and structural biological approaches. In particular, structure-function analysis of the cell-surface glycan-binding proteins and glycoside hydrolases of the S. copri MLG-PUL revealed the molecular basis for glycan capture and saccharification. Notably, syntenic MLG-PULs from human gut, human oral, and ruminant gut Prevotellaceae are distinguished from their counterparts in Bacteroidaceae by the presence of a β(1,3)-specific endo-glucanase from glycoside hydrolase family 5, subfamily 4 (GH5_4) that initiates MLG backbone cleavage. The definition of a family of homologous MLG-PULs in individual species enabled a survey of nearly 2000 human fecal microbiomes using these genes as molecular markers, which revealed global population-specific distributions of Bacteroidaceae- and Prevotellaceae-mediated MLG utilization. Altogether, the data presented here provide new insight into the molecular basis of β-glucan metabolism in the HGM, as a basis for informing the development of approaches to improve the nutrition and health of humans and other animals.