| Structural highlights
6dht is a 1 chain structure with sequence from Baco1. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance.
| | Ligands: | , , , , , |
| Gene: | BACOVA_02649 (BACO1) |
| Activity: | Xyloglucan-specific endo-beta-1,4-glucanase, with EC number 3.2.1.151 |
| Resources: | FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT |
Function
[BGH9A_BACO1] Catalyzes endohydrolysis of 1,4-beta-D-glucosidic linkages in xyloglucan with retention of the beta-configuration of the glycosyl residues in xyloglucan degradation. Cleaves the backbone of the 3 major types of natural xyloglucans (seed galactoxyloglucan from tamarind kernel, dicot fucogalactoxyloglucan from lettuce leaves, and solanaceous arabinogalactoxyloglucan from tomato fruit), to produce xyloglucan oligosaccharides. May be superfluous in xyloglucan degradation compared to BoGH5A (AC A7LXT7), the other Xyloglucan-specific endo-beta-1,4-glucanase.[1]
Publication Abstract from PubMed
Dietary fiber is an important food source for members of the human gut microbiome. Members of the dominant Bacteroidetes phylum capture diverse polysaccharides via the action of multiple cell surface proteins encoded within polysaccharide utilization loci (PUL). The independent activities of PUL-encoded glycoside hydrolases (GHs) and surface glycan-binding proteins (SGBPs) for the harvest of various glycans have been studied in detail, but how these proteins work together to coordinate uptake is poorly understood. Here, we combine genetic and biochemical approaches to discern the interplay between the BoGH9 endoglucanase and the xyloglucan-binding proteins SGBP-A and SGBP-B from the Bacteroides ovatus xyloglucan utilization locus (XyGUL). The expression of BoGH9, a weakly active xyloglucanase in isolation, is required in a strain that expresses a non-binding version of SGBP-A (SGBP-A*). The crystal structure of the BoGH9 enzyme suggests the molecular basis for its robust activity on mixed-linkage beta-glucan compared to xyloglucan. However, catalytically inactive site-directed mutants of BoGH9 fail to complement the deletion of the active BoGH9 in a SGBP-A* strain. We also find that SGBP-B is needed in an SGBP-A* background to support growth on xyloglucan, but that the non-binding SGBP-B* protein acts in a dominant negative manner to inhibit growth on xyloglucan. We postulate a model whereby the SGBP-A, SGBP-B, and BoGH9 work together at the cell surface, likely within a discrete complex, and that xyloglucan binding by SGBP-B and BoGH9 may facilitate the orientation of the xyloglucan for transfer across the outer membrane.
A Cell-Surface GH9 Endo-Glucanase Coordinates with Surface Glycan-Binding Proteins to Mediate Xyloglucan Uptake in the Gut Symbiont Bacteroides ovatus.,Foley MH, Dejean G, Hemsworth GR, Davies GJ, Brumer H, Koropatkin NM J Mol Biol. 2019 Mar 1;431(5):981-995. doi: 10.1016/j.jmb.2019.01.008. Epub 2019 , Jan 19. PMID:30668971[2]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
References
- ↑ Larsbrink J, Rogers TE, Hemsworth GR, McKee LS, Tauzin AS, Spadiut O, Klinter S, Pudlo NA, Urs K, Koropatkin NM, Creagh AL, Haynes CA, Kelly AG, Cederholm SN, Davies GJ, Martens EC, Brumer H. A discrete genetic locus confers xyloglucan metabolism in select human gut Bacteroidetes. Nature. 2014 Jan 19. doi: 10.1038/nature12907. PMID:24463512 doi:http://dx.doi.org/10.1038/nature12907
- ↑ Foley MH, Dejean G, Hemsworth GR, Davies GJ, Brumer H, Koropatkin NM. A Cell-Surface GH9 Endo-Glucanase Coordinates with Surface Glycan-Binding Proteins to Mediate Xyloglucan Uptake in the Gut Symbiont Bacteroides ovatus. J Mol Biol. 2019 Mar 1;431(5):981-995. doi: 10.1016/j.jmb.2019.01.008. Epub 2019 , Jan 19. PMID:30668971 doi:http://dx.doi.org/10.1016/j.jmb.2019.01.008
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