7byx

Crystal structure of exo-beta-1,3-galactanase from Phanerochaete chrysosporium Pc1,3Gal43A E208A with beta-1,3-galactotriose

spinqualitylabelsall models 7byx, resolution 2.30Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 7byx is a 4 chain structure with sequence from Phanerodontia chrysosporium. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Method: X-ray diffraction, Resolution 2.3Å Ligands: ACT, BMA, CA, GAL, GOL, MAN, NAG, NDG Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function Q50KB2_PHACH Publication Abstract from PubMed Arabinogalactan proteins (AGPs) are plant proteoglycans with functions in growth and development. However, these functions are largely unexplored, mainly because of the complexity of the sugar moieties. These carbohydrate sequences are generally analyzed with the aid of glycoside hydrolases. The exo-beta-1,3-galactanase is a glycoside hydrolase from the basidiomycete Phanerochaete chrysosporium (Pc1,3Gal43A), which specifically cleaves AGPs. However, its structure is not known in relation to its mechanism bypassing side chains. In this study, we solved the apo and liganded structures of Pc1,3Gal43A, which reveal a glycoside hydrolase family 43 subfamily 24 (GH43_sub24) catalytic domain together with a carbohydrate-binding module family (CBM) 35 binding domain. GH43_sub24 is known to lack the catalytic base Asp conserved among other GH43 subfamilies. Our structure in combination with kinetic analyses reveal that the tautomerized imidic acid group of Gln263 serves as the catalytic base residue instead. Pc1,3Gal43A has three subsites that continue from the bottom of the catalytic pocket to the solvent. Subsite -1 contains a space that can accommodate the C-6 methylol of Gal, enabling the enzyme to bypass the beta-1,6-linked galactan side chains of AGPs. Furthermore, the galactan-binding domain in CBM35 has a different ligand interaction mechanism from other sugar-binding CBM35s, including those that bind galactomannan. Specifically, we noted a Gly->Trp substitution, which affects pyranose stacking, and an Asp->Asn substitution in the binding pocket, which recognizes beta-linked rather than alpha-linked Gal residues. These findings should facilitate further structural analysis of AGPs and may also be helpful in engineering designer enzymes for efficient biomass utilization. Unique active site and subsite features in the arabinogalactan-degrading GH43 exo-beta-1,3-galactanase from Phanerochaete chrysosporium.,Matsuyama K, Kishine N, Fujimoto Z, Sunagawa N, Kotake T, Tsumuraya Y, Samejima M, Igarashi K, Kaneko S J Biol Chem. 2020 Oct 22. pii: RA120.016149. doi: 10.1074/jbc.RA120.016149. PMID:33093171 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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