Glycosyl hydrolase family 43 protein such as Halothermothrix orenii H 168 alpha-L-arabinofuranosidase (HoAraf43;Hore_20580). This glycosyl hydrolase family 43 (GH43) subgroup includes Halothermothrix orenii H 168 alpha-L-arabinofuranosidase (EC 3.2.1.55) (HoAraf43;Hore_20580). It belongs to the glycosyl hydrolase clan F (according to carbohydrate-active enzymes database (CAZY)) which includes family 43 (GH43) and 62 (GH62) families. This GH43_ HoAraf43-like subgroup includes enzymes that have been annotated as having xylan-digesting beta-xylosidase (EC 3.2.1.37) and xylanase (endo-alpha-L-arabinanase, EC 3.2.1.8) activities. GH43 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. Many GH43 enzymes display both alpha-L-arabinofuranosidase and beta-D-xylosidase activity using aryl-glycosides as substrates. A common structural feature of GH43 enzymes is a 5-bladed beta-propeller domain that contains the catalytic acid and catalytic base. A long V-shaped groove, partially enclosed at one end, forms a single extended substrate-binding surface across the face of the propeller.
Glycosyl hydrolase families 43 and 62 form CAZY clan GH-F. This glycosyl hydrolase clan F (according to carbohydrate-active enzymes database (CAZY)) includes family 43 (GH43) and 62 (GH62). GH43 includes enzymes with beta-xylosidase (EC 3.2.1.37), beta-1,3-xylosidase (EC 3.2.1.-), alpha-L-arabinofuranosidase (EC 3.2.1.55), arabinanase (EC 3.2.1.99), xylanase (EC 3.2.1.8), endo-alpha-L-arabinanases (beta-xylanases) and galactan 1,3-beta-galactosidase (EC 3.2.1.145) activities. GH62 includes enzymes characterized as arabinofuranosidases (alpha-L-arabinofuranosidases; EC 3.2.1.55) that specifically cleave either alpha-1,2 or alpha-1,3-L-arabinofuranose side chains from xylans. GH43 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. Many of the enzymes in this family display both alpha-L-arabinofuranosidase and beta-D-xylosidase activity using aryl-glycosides as substrates. GH62 are also predicted to be inverting enzymes. A common structural feature of both, GH43 and GH62 enzymes, is a 5-bladed beta-propeller domain that contains the catalytic acid and catalytic base. A long V-shaped groove, partially enclosed at one end, forms a single extended substrate-binding surface across the face of the propeller.
Glycosyl hydrolase family 130, such as beta-mammosidase BT3780 and BACOVA_03624. This subfamily contains glycosyl hydrolase family 130, as classified by the carbohydrate-active enzymes database (CAZY), and includes Bacteroides enzymes, BT3780 and BACOVA_03624. Members of this family possess 5-bladed beta-propeller domains similar to families 32, 43, 62, 68, 117 (GH32, GH43, GH62, GH68, GH117). GH130 enzymes are involved in the bacterial utilization of mannans or N-linked glycans. GH130 enzymes have also been shown to target beta-1,2- and beta-1,4-mannosidic linkages where these phosphorylases mediate bond cleavage by a single displacement reaction in which phosphate functions as the catalytic nucleophile. However, some lack the conserved basic residues that bind the phosphate nucleophile, as observed for the Bacteroides enzymes, BT3780 and BACOVA_03624, which are indeed beta-mannosidases that hydrolyze beta-1,2-mannosidic linkages through an inverting mechanism.
Glycoside hydrolase family 130. Members of the glycosyl hydrolase family 130, as classified by the carbohydrate-active enzymes database (CAZY), are phosphorylases and hydrolases for beta-mannosides, and include beta-1,4-mannosylglucose phosphorylase (EC 2.4.1.281), beta-1,4-mannooligosaccharide phosphorylase (EC 2.4.1.319), beta-1,4-mannosyl-N-acetyl-glucosamine phosphorylase (EC 2.4.1.320), beta-1,2-mannobiose phosphorylase (EC 2.4.1.-), beta-1,2-oligomannan phosphorylase (EC 2.4.1.-) and beta-1,2-mannosidase (EC 3.2.1.-). They possess 5-bladed beta-propeller domains similar to families 32, 43, 62, 68, 117 (GH32, GH43, GH62, GH68, GH117). GH130 enzymes are involved in the bacterial utilization of mannans or N-linked glycans. Beta-1,4-mannosylglucose phosphorylase is involved in degradation of beta-1,4-D-mannosyl-N-acetyl-D-glucosamine linkages in the core of N-glycans; it produces alpha-mannose 1-phosphate and glucose from 4-O-beta-D-mannosyl-D-glucose and inorganic phosphate, using a critical catalytic Asp as a proton donor.
Glycoside hydrolase family 130. Members of the glycosyl hydrolase family 130, as classified by the carbohydrate-active enzymes database (CAZY), are phosphorylases and hydrolases for beta-mannosides, and include beta-1,4-mannosylglucose phosphorylase (EC 2.4.1.281), beta-1,4-mannooligosaccharide phosphorylase (EC 2.4.1.319), beta-1,4-mannosyl-N-acetyl-glucosamine phosphorylase (EC 2.4.1.320), beta-1,2-mannobiose phosphorylase (EC 2.4.1.-), beta-1,2-oligomannan phosphorylase (EC 2.4.1.-) and beta-1,2-mannosidase (EC 3.2.1.-). They possess 5-bladed beta-propeller domains similar to families 32, 43, 62, 68, 117 (GH32, GH43, GH62, GH68, GH117). GH130 enzymes are involved in the bacterial utilization of mannans or N-linked glycans. Beta-1,4-mannosylglucose phosphorylase is involved in degradation of beta-1,4-D-mannosyl-N-acetyl-D-glucosamine linkages in the core of N-glycans; it produces alpha-mannose 1-phosphate and glucose from 4-O-beta-D-mannosyl-D-glucose and inorganic phosphate, using a critical catalytic Asp as a proton donor.
Crystalstructure of a thermostable family-43 glycoside hydrolase [Halothermothrix orenii H 168],4QQS_B Crystal structure of a thermostable family-43 glycoside hydrolase [Halothermothrix orenii H 168]