6hf4

The structure of BoMan26B, a GH26 beta-mannanase from Bacteroides ovatus, complexed with G1M4

spinqualitylabelsall models 6hf4, resolution 1.78Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 6hf4 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: BMA, CA, CL, GLA Related: 6hf2 Gene: BACOVA_02093 (BACO1) Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Publication Abstract from PubMed The galactomannan utilization locus (BoManPUL) of the human gut bacterium Bacteroides ovatus encodes BoMan26B, a cell-surface-exposed endomannanase whose functional and structural features have been unclear. Our study now places BoMan26B in context with related enzymes and reveals the structural basis for its specificity. BoMan26B prefers longer substrates and is less restricted by galactose side-groups than the mannanase BoMan26A of the same locus. Using galactomannan, BoMan26B generated a mixture of (galactosyl) manno-oligosaccharides shorter than mannohexaose. Three defined manno-oligosaccharides had affinity for the SusD-like surface-exposed glycan-binding protein, predicted to be implicated in saccharide transport. Co-incubation of BoMan26B and the periplasmic alpha-galactosidase BoGal36A increased the rate of galactose release by about 10-fold compared with the rate without BoMan26B. The results suggested that BoMan26B performs the initial attack on galactomannan, generating oligosaccharides that after transport to the periplasm are processed by BoGal36A. A crystal structure of BoMan26B with galactosyl-mannotetraose bound in subsites -5 to -2 revealed an open and long active-site cleft with Trp-112 in subsite -5 concluded to be involved in mannosyl interaction. Moreover, Lys-149 in the -4 subsite interacted with the galactosyl side-group of the ligand. A phylogenetic tree consisting of GH26 enzymes revealed four strictly conserved GH26 residues and disclosed that BoMan26A and BoMan26B reside on two distinct phylogenetic branches (A and B). The three other branches contain lichenases, xylanases, or enzymes with unknown activities. Lys-149 is conserved in a narrow part of branch B, and Trp-112 is conserved in a wider group within branch B. A surface-exposed GH26 beta-mannanase from Bacteroides ovatus: Structure, role, and phylogenetic analysis of BoMan26B.,Bagenholm V, Wiemann M, Reddy SK, Bhattacharya A, Rosengren A, Logan DT, Stalbrand H J Biol Chem. 2019 Jun 7;294(23):9100-9117. doi: 10.1074/jbc.RA118.007171. Epub, 2019 Apr 18. PMID:31000630 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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