?cl14647: GH43_62_32_68_117_130 Superfamily
 
Glycosyl hydrolase families: GH43, GH62, GH32, GH68, GH117, CH130 Members of the glycosyl hydrolase families 32, 43, 62, 68, 117 and 130 (GH32, GH43, GH62, GH68, GH117, GH130) all possess 5-bladed beta-propeller domains and comprise clans F and J, as classified by the carbohydrate-active enzymes database (CAZY). Clan F consists of families GH43 and GH62. GH43 includes beta-xylosidases (EC 3.2.1.37), beta-xylanases (EC 3.2.1.8), alpha-L-arabinases (EC 3.2.1.99), and alpha-L-arabinofuranosidases (EC 3.2.1.55), using aryl-glycosides as substrates, while family GH62 contains alpha-L-arabinofuranosidases (EC 3.2.1.55) that specifically cleave either alpha-1,2 or alpha-1,3-L-arabinofuranose sidechains from xylans. These are inverting enzymes (i.e. they invert the stereochemistry of the anomeric carbon atom of the substrate) that have an aspartate as the catalytic general base, a glutamate as the catalytic general acid and another aspartate that is responsible for pKa modulation and orienting the catalytic acid. Clan J consists of families GH32 and GH68. GH32 comprises sucrose-6-phosphate hydrolases, invertases (EC 3.2.1.26), inulinases (EC 3.2.1.7), levanases (EC 3.2.1.65), eukaryotic fructosyltransferases, and bacterial fructanotransferases while GH68 consists of frucosyltransferases (FTFs) that include levansucrase (EC 2.4.1.10); beta-fructofuranosidase (EC 3.2.1.26); inulosucrase (EC 2.4.1.9), while GH68 consists of frucosyltransferases (FTFs) that include levansucrase (EC 2.4.1.10); beta-fructofuranosidase (EC 3.2.1.26); inulosucrase (EC 2.4.1.9), all of which use sucrose as their preferential donor substrate. Members of this clan are retaining enzymes (i.e. they retain the configuration at anomeric carbon atom of the substrate) that catalyze hydrolysis in two steps involving a covalent glycosyl enzyme intermediate: an aspartate located close to the N-terminus acts as the catalytic nucleophile and a glutamate acts as the general acid/base; a conserved aspartate residue in the Arg-Asp-Pro (RDP) motif stabilizes the transition state. Structures of all families in the two clans manifest a funnel-shaped active site that comprises two subsites with a single route for access by ligands. Also included in this superfamily are GH117 enzymes that have exo-alpha-1,3-(3,6-anhydro)-l-galactosidase activity, removing terminal non-reducing alpha-1,3-linked 3,6-anhydro-l-galactose residues from their neoagarose substrate, and GH130 that are phosphorylases and hydrolases for beta-mannosides, involved in the bacterial utilization of mannans or N-linked glycans. |
Jiyao W et al.(2023). "The conserved domain database in 2023.",