Glycoside Hydrolase Family 115

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• Author: Satoshi Kaneko
• Responsible Curator: Satoshi Kaneko

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Glycoside Hydrolase Family GH115
Clan	none
Mechanism	inverting
Active site residues	not known
CAZy DB link
https://www.cazy.org/GH115.html

Substrate specificities

Glycoside hydrolases of GH115 display α-glucuronidase activity. In particular, members of this family catalyze the cleavage of 4-O-methyl D-glucuronic acid sidechains from native xylan polysaccharides (EC 3.2.1.131). In contrast to GH67 enzymes, which only cleave glucuronosyl linkages at the non-reducing ends of xylooligosaccharides, GH115 enzymes remove glucuronic acid from the both terminal and internal regions of xylooligosaccharides and xylans [1]. This substrate specificity was first demonstrated by an α-glucuronidase purified from Thermoascus aurantiacus [2], and later for a Schizophyllum commune α-glucuronidase [3]. Although GH115 was established on the basis of biochemical and sequence analysis of Pichia stipitis (4-O-methyl)-α-glucuronidase [1], available N-terminal protein sequence of the S. commune enzyme [3] allowed the tentative assignment of this enzyme to GH115 [1], which was later confirmed by the full protein sequence [4]. A GH115 member from Streptomyces pristinaespiralis produces both 4-O-methyl-D-glucuronic acid and non-methylated D-glucuronic acid from xylan and xylo-oligosaccharides [5].

Kinetics and Mechanism

Using reduced aldopentauronic acid (MeGlcA3Xyl4-ol) as a substrate, analysis by ¹H-NMR spectroscopy revealed that the enzymes from both S. commune and P. stipitis release the β-anomer of 4-O-methyl-D-glucuronic acid (MeGlcA) as the first-formed product, thus suggesting a one step, inverting mechanism [6].

Catalytic Residues

The catalytic residues have not yet been identified in a member of this family.

Three-dimensional structures

No 3D structure has been solved for this family at present, although crystallization of a Streptomyces pristinaespiralis homolog has been reported [5].

Family Firsts

First stereochemistry determination

Release of the β-anomer of 4-methyl-D-glucuronic acid by both the Schizophyllum commune and Pichia stipitis enzymes using ¹H NMR [6].

First general acid residue identification

Not yet identified.

First general base residue identification

Not yet identified.

First 3-D structure

Crystallization of the Streptomyces pristinaespiralis family member has been reported [5].

References

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1. Ryabova O, Vrsanská M, Kaneko S, van Zyl WH, and Biely P. (2009). A novel family of hemicellulolytic alpha-glucuronidase. FEBS Lett. 2009;583(9):1457-62. DOI:10.1016/j.febslet.2009.03.057 |
2. Khandke KM, Vithayathil PJ, and Murthy SK. (1989). Purification and characterization of an alpha-D-glucuronidase from a thermophilic fungus, Thermoascus aurantiacus. Arch Biochem Biophys. 1989;274(2):511-7. DOI:10.1016/0003-9861(89)90464-5 |
3. Tenkanen M and Siika-aho M. (2000). An alpha-glucuronidase of Schizophyllum commune acting on polymeric xylan. J Biotechnol. 2000;78(2):149-61. DOI:10.1016/s0168-1656(99)00240-0 |
5. Fujimoto Z, Ichinose H, Biely P, and Kaneko S. (2011). Crystallization and preliminary crystallographic analysis of the glycoside hydrolase family 115 α-glucuronidase from Streptomyces pristinaespiralis. Acta Crystallogr Sect F Struct Biol Cryst Commun. 2011;67(Pt 1):68-71. DOI:10.1107/S1744309110043721 |