The human gut microbe Bacteroides thetaiotaomicron encodes the founding member of a novel glycosaminoglycan-degrading polysaccharide lyase family PL29

• Published in: The Journal of biological chemistry Vol. 293; no. 46; pp. 17906 - 17916
• Main Authors: Ndeh, Didier, Munoz Munoz, Jose, Cartmell, Alan, Bulmer, David, Wills, Corinne, Henrissat, Bernard, Gray, Joseph
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 16.11.2018; American Society for Biochemistry and Molecular Biology
• Subjects: Bacterial Proteins - chemistry; Bacterial Proteins - metabolism; Bacteroides thetaiotaomicron - enzymology; Chemical and Process Engineering; Chondroitin Sulfates - metabolism; Dermatan Sulfate - metabolism; Engineering Sciences; Enzymology; Food engineering; Hyaluronic Acid - metabolism; Hydrogen-Ion Concentration; Life Sciences; Metals, Heavy - chemistry; Polysaccharide-Lyases - chemistry; Polysaccharide-Lyases - metabolism; Temperature; bacterial metabolism; polysaccharide; carbohydrate metabolism; PL29; chondroitin sulfate; hyaluronan; CAZymes; human gut microbiota; cell surface enzyme; glycosaminoglycan degradation; hyaluronate lyase; Cazymes
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1074/jbc.RA118.004510

Glycosaminoglycans (GAGs) and GAG-degrading enzymes have wide-ranging applications in the medical and biotechnological industries. The former are also an important nutrient source for select species of the human gut microbiota (HGM), a key player in host–microbial interactions. How GAGs are metabolized by the HGM is therefore of interest and has been extensively investigated in the model human gut microbe Bacteroides thetaiotaomicron. The presence of as-yet uncharacterized GAG-inducible genes in its genome and of related species, however, is testament to our incomplete understanding of this process. Nevertheless, it presents a potential opportunity for the discovery of additional GAG-degrading enzymes. Here, we investigated a gene of unknown function (BT_3328) from the chondroitin sulfate (CS) utilization locus of B. thetaiotaomicron. NMR and UV spectroscopic assays revealed that it encodes a novel polysaccharide lyase (PL), hereafter referred to as BtCDH, reflecting its source (B. thetaiotaomicron (Bt)) and its ability to degrade the GAGs CS, dermatan sulfate (DS), and hyaluronic acid (HA). When incubated with HA, BtCDH generated a series of unsaturated HA sugars, including Δ4,5UA-GlcNAc, Δ4,5UA-GlcNAc-GlcA-GlcNac, Δ4,5UA-[GlcNAc-GlcA]2-GlcNac, and Δ4,5UA-[GlcNAc-GlcA]3-GlcNac, as end products and hence was classed as endo-acting. A combination of genetic and biochemical assays revealed that BtCDH localizes to the cell surface of B. thetaiotaomicron where it enables extracellular GAG degradation. BtCDH homologs were also detected in several other HGM species, and we therefore propose that it represents the founding member of a new polysaccharide lyase family (PL29). The current discovery also contributes new insights into CS metabolism by the HGM.