Glycoside Hydrolase Family 174

This page is currently under construction. This means that the Responsible Curator has deemed that the page's content is not quite up to CAZypedia's standards for full public consumption. All information should be considered to be under revision and may be subject to major changes.

• Author: Guanchen Liu

• Responsible Curator: Yaoguang Chang

---

Glycoside Hydrolase Family GH174
Clan	GH-x
Mechanism	retaining/inverting
Active site residues	known/not known
CAZy DB link
http://www.cazy.org/GH174.html

Substrate specificities

Members of glycoside hydrolase family 174 have been shown to exhibit α-1,3-L-fucanase activity. The first member of this family, Fun174A from a marine bacterium Wenyingzhuangia aestuarii OF219, 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 processive endo-acting manner.[1] Meanwhile, three homologs of Fun174A from Rubritalea marina, Spartobacteria bacterium and Wenyingzhuangia fucanilytica, display activities toward sulfated fucan from Isostichopus badionotus.[1] All 92 members (up to May,2023) of GH174 are bacterial enzymes.

Figure 1. The phylogenetic tree of GH174 homologs. Sequences comfirmed to exhibit α-1,3-L-fucanase activity were in red.

Kinetics and Mechanism

The catalytic mechanism of GH174 has not been identified. As mentioned in the report, Fun174A showed no transglycosylating activity in the tested acceptor substrates, such as glycerin, methanol, L-fucose, D-glucose, D-galactose, D-fructose, D-mannose, D-glucosamine and N-acetyl- D-glucosamine.[1]

Catalytic Residues

Multiple sequence alignments of GH174 homologs showed that D119, E120 and E218 in Fun174A were highly conserved in all sequences. Three single-site mutants D119E, E120A and E218Q were established, expressed and identified in the report. Mutant D119E, E120A and E218Q resulted in 100.0%, 85.7% and 88.3% loss of activity on sulfated fucan from Isostichopus badionotus respectively. It indicated that D119, E120 and E218 were critical for the functioning of Fun174A.[1]

Figure 2. Multiple sequence alignments of residues in GH174 homologs. The highly conserved acidic amino acids 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. Liu G, Shen J, Chang Y, Mei X, Chen G, Zhang Y, and Xue C. (2023). Characterization of an endo-1,3-fucanase from marine bacterium Wenyingzhuangia aestuarii: The first member of a novel glycoside hydrolase family GH174. Carbohydr Polym. 2023;306:120591. DOI:10.1016/j.carbpol.2023.120591 |