Glycoside Hydrolase Family 168

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• Author: Jingjing Shen
• Responsible Curator: Yaoguang Chang

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Glycoside Hydrolase Family GH168
Clan	GH-x
Mechanism	retaining
Active site residues	not known
CAZy DB link
https://www.cazy.org/GH168.html

Substrate specificities

Members of glycoside hydrolase family 168 have been shown to exhibit α-1,3-L-fucanase activity. The first member of this family, Fun168A from a marine bacterium Wenyingzhuangia funcanilytica CZ1127^T, specifically hydrolyze the α-1,3- L-fucoside bonds between 2-O-sulfated and non-sulfated fucose residues in the sulfated fucan from sea cucumber Isostichopus badionotus in a random endo-acting manner [1]. Meanwhile, five homologues of Fun168A display activities toward sulfated fucan from Isostichopus badionotus, namely WP_081987558.1, WP_068826447.1, WP_068826442.1, OHE80969.1 and WP_083194720.1.

Figure 1. The phylogenetic tree of GH168 homologues. Sequences comfirmed to exhibit α-1,3-L-fucanase activity were in red.

Kinetics and Mechanism

As mentioned in the report, Fun168A exhibited transglycosylating activity with glycerin, methanol, and L-fucose as acceptors. The transglycosylating activity of Fun168A implied its retaining mechanism in catalysis [1].

Catalytic Residues

Multiple sequence alignments of GH168 homologues showed that D206 and E264 in Fun168A were strictly conserved in all sequences. Two single-site mutants D206E and E264Q were established, expressed and identified in the report. These two mutants were all inactive on Ib-FUC, indicating that D206 and E264 were critical for the activity of Fun168A [1].

Figure 2. Multiple sequence alignments of residues in GH168 homologues. The strictly conserved residues in all sequences were indicated with black triangles.

Three-dimensional structures

No three-dimensional structure has been solved in this glycoside hydrolase family at present.

Family Firsts

First stereochemistry determination

Not yet identified.

First catalytic nucleophile identification

Not yet identified.

First general acid/base residue identification

Not yet identified.

First 3-D structure

Not yet identified.

References

1. Shen J, Chang Y, Zhang Y, Mei X, and Xue C. (2020). Discovery and Characterization of an Endo-1,3-Fucanase From Marine Bacterium Wenyingzhuangia fucanilytica: A Novel Glycoside Hydrolase Family. Front Microbiol. 2020;11:1674. DOI:10.3389/fmicb.2020.01674 |