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Glycoside Hydrolase Family 80

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Glycoside Hydrolase Family GH80
Clan GH-I
Mechanism not determined
Active site residues inferred
CAZy DB link

Substrate specificities

Glycoside hydrolase family GH80 is comprised of endo-acting β-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. As a member of clan GH-I, a lysozyme-like α-β fold is suggested, based on known GH24 and GH46 structures.

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


  1. Park JK, Shimono K, Ochiai N, Shigeru K, Kurita M, Ohta Y, Tanaka K, Matsuda H, and Kawamukai M. (1999). Purification, characterization, and gene analysis of a chitosanase (ChoA) from Matsuebacter chitosanotabidus 3001. J Bacteriol. 1999;181(21):6642-9. DOI:10.1128/JB.181.21.6642-6649.1999 | PubMed ID:10542164 [Park1999]
  2. 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. 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. Shimono K, Shigeru K, Tsuchiya A, Itou N, Ohta Y, Tanaka K, Nakagawa T, Matsuda H, and Kawamukai M. (2002). Two glutamic acids in chitosanase A from Matsuebacter chitosanotabidus 3001 are the catalytically important residues. J Biochem. 2002;131(1):87-96. DOI:10.1093/oxfordjournals.jbchem.a003081 | PubMed ID:11754739 [Shimono2002]
  5. Sigrist CJ, Cerutti L, de Castro E, Langendijk-Genevaux PS, Bulliard V, Bairoch A, and Hulo N. (2010). PROSITE, a protein domain database for functional characterization and annotation. Nucleic Acids Res. 2010;38(Database issue):D161-6. DOI:10.1093/nar/gkp885 | PubMed ID:19858104 [Sigrist2010]
  6. Tremblay H, Blanchard J, and Brzezinski R. (2000). A common molecular signature unifies the chitosanases belonging to families 46 and 80 of glycoside hydrolases. Can J Microbiol. 2000;46(10):952-5. | Google Books | Open Library PubMed ID:11068683 [Tremblay2000]
  7. [CAZYGHpage]
  8. Amakata D, Matsuo Y, Shimono K, Park JK, Yun CS, Matsuda H, Yokota A, and Kawamukai M. (2005). Mitsuaria chitosanitabida gen. nov., sp. nov., an aerobic, chitosanase-producing member of the 'Betaproteobacteria'. Int J Syst Evol Microbiol. 2005;55(Pt 5):1927-1932. DOI:10.1099/ijs.0.63629-0 | PubMed ID:16166689 [Amakata2005]

All Medline abstracts: PubMed