Glycoside Hydrolase Family 79

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• Author: ^^^Satoshi Kaneko^^^
• Responsible Curator: ^^^Satoshi Kaneko^^^

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Glycoside Hydrolase Family GH79
Clan	GH-A
Mechanism	retaining
Active site residues	known
CAZy DB link
https://www.cazy.org/GH79.html

Substrate specificities

Family GH79 enzymes are found widely distributed in bacteria and eukaryota including fungi, plants, and animals. The characterized activities of this family include β-glucuronidase (E.C. 3.2.1.31) [1], β-4-O-methyl-glucuronidase (E.C. 3.2.1.-) [2], baicalin β-glucuronidase (E.C. 3.2.1.167) [3], heparanase (E.C. 3.2.1.-) [] and hyaluronidase (E.C. 3.2.1.-) []. Some β-glucuronidase have been shown to release both glucuronic acid (GlcA) and 4-O-methyl-GlcA from arabinogalactan proteins [2, 4]. The Aspergillus niger enzyme shows high activity for 4-O-methyl-GlcA residues [2]. Scutellaria baicalensis β-glucuronidase hydrolyzes baicalein 7-O-β-glucuronide, which is a major flavone of S. baicalensis [3].

Kinetics and Mechanism

GH79 β-glucuronidases are retaining enzymes, as first demonstrated by proton-NMR studies of the hydrolysis of p-nitrophenyl β-glucuronide by a β-glucuronidase from Acidobacterium capsulatum [5].

Catalytic Residues

The catalytic residues were first identified in the A. capsulatum β-glucuronidase as Glu173 (acid/base) and Glu287 (nucleophile) by trapping of the 2-fluoroglucuronyl-enzyme intermediate and the mutagenesis studies [5].

Three-dimensional structures

The three-dimensional structure of A. capsulatum β-glucuronidase solved using X-ray crystallography represented the first structure of an enzyme of GH79 [5]. The catalytic domain of the enzyme is a (β/α)8 TIM-barrel fold as members of clan GH-A.

Family Firsts

First stereochemistry determination

Acidobacterium capsulatum β-glucuronidase by 1H-NMR [5].

First catalytic nucleophile identification

A. capsulatum β-glucuronidase by 2-fluoroglucuroic acid labeling and the mutagenesis study [5].

First general acid/base residue identification

A. capsulatum β-glucuronidase by structural identification and the mutagenesis study [5].

First 3-D structure

A. capsulatum β-glucuronidase [5].

References

1. Eudes A, Mouille G, Thévenin J, Goyallon A, Minic Z, and Jouanin L. (2008). Purification, cloning and functional characterization of an endogenous beta-glucuronidase in Arabidopsis thaliana. Plant Cell Physiol. 2008;49(9):1331-41. DOI:10.1093/pcp/pcn108 |
2. Kuroyama H, Tsutsui N, Hashimoto Y, and Tsumuraya Y. (2001). Purification and characterization of a beta-glucuronidase from Aspergillus niger. Carbohydr Res. 2001;333(1):27-39. DOI:10.1016/s0008-6215(01)00114-8 |
3. Sasaki K, Taura F, Shoyama Y, and Morimoto S. (2000). Molecular characterization of a novel beta-glucuronidase from Scutellaria baicalensis georgi. J Biol Chem. 2000;275(35):27466-72. DOI:10.1074/jbc.M004674200 |
4. Konishi T, Kotake T, Soraya D, Matsuoka K, Koyama T, Kaneko S, Igarashi K, Samejima M, and Tsumuraya Y. (2008). Properties of family 79 beta-glucuronidases that hydrolyze beta-glucuronosyl and 4-O-methyl-beta-glucuronosyl residues of arabinogalactan-protein. Carbohydr Res. 2008;343(7):1191-201. DOI:10.1016/j.carres.2008.03.004 |

5. (2012) Michikawa M, Ichinose H, Mitsuru M, Peter Biely, Seino Jongkees, Makoto Yoshida, Toshihisa Kotake, Yoichi Tsumuraya, Stephen Withers, Zui Fujimoto, and Satoshi Kaneko. Structural and biochemical characterization of glycoside hydrolase family 79 β-glucuronidase from Acidobacterium capsulatum. J Biol Chem. in press.