Glycoside Hydrolase Family 80

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• Author: ^^^Ryszard Brzezinski^^^
• Responsible Curator: ^^^Ryszard Brzezinski^^^

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Glycoside Hydrolase Family GH80
Clan	GH-I
Mechanism	not determined
Active site residues	inferred
CAZy DB link
https://www.cazy.org/GH80.html

Substrate specificities

Glycoside hydrolase family GH80 is comprised of endo-acting beta-1,4-chitosanases of bacterial origin. The first characterized member was from a proteobacterium [1] belonging to the Bacteroidetes/Chlorobi group [2, 3]. At present (July 2011), GH80 is very small family, comprised of fewer than 20 members.

Characterized GH80 members do not hydrolyze chitin or cellulose [1, 3], and for one member, the chitosan hexa-oligosaccharide (GlcN)₆ is preferentially hydrolyzed into two molecules of the trisaccharide [4].

Kinetics and Mechanism

The stereochemistry of the hydrolytic reaction catalyzed by GH80 members has not yet been studied. However, sequence similarity with members of Clan GH-I suggests that these enzymes may operate with inversion of the anomeric configuration (see Catalytic Residues, below)

Catalytic Residues

The chitosanases from family GH80 share a PROSITE signature motif [5] with the chitosanases from family GH46 [6]. Together with GH24, these three families comprise Clan GH-I [7].

A site-directed mutagenesis study of the chitosanase A from Matsuebacter chitosanotabidus 3001 (new name: Mitsuaria chitosanitabida [8]) identified two residues as essentiel for catalysis: Glu-121 (in the sequence YPENG)and Glu-141 (in the sequence DYEAA) [4].

Three-dimensional structures

No three-dimensional structure has yet been solved for this family.

Family Firsts

First primary sequence determination

Chitosanase ChoA from Matsuebacter chitosanotabidus 3001 (now Mitsuaria chitosanitabida) [1, 8]

First stereochemistry determination

Not yet determined

First catalytic nucleophile identification

Not yet identified

First general acid/base residue identification

Not yet identified

First 3-D structure

Not yet determined

References

<biblio>

1. Park1999 pmid=10542164
2. Matsuda2001 Matsuda, Y., Iida, I., Shinogi, T., Kakutani, K., Nonomura, T., Toyoda, H. (2001) In vitro suppression of mycelial growth of Fusarium oxysporum by extracellular chitosanase of Sphingobacterium multivorum and cloning of the chitosanase gene csnSM1. J. Gen. Plant Pathol. 67, 318-324.
3. Yi2004 Yi, J.-H., Jang, H.-K., Lee, S.-J., Lee, K.-E., Choi, S.-G. (2004) Purification and properties of chitosanase from chitinolytic beta-Proteobacterium KNU3. J. Microbiol. Biotechnol. 14, 337-343.
4. Shimono2002 pmid=11754739
5. Tremblay2000 pmid=11068683
6. Sigrist2010 pmid=19858104
7. Amakata2005 pmid=16166689
8. CAZYGHpage http://www.cazy.org/Glycoside-Hydrolases.html