PROSITE documentation PDOC00640
Glycosyl hydrolases family 8 signature


The microbial degradation of cellulose and xylans requires several types of enzymes such as endoglucanases (EC, cellobiohydrolases (EC (exoglucanases), or xylanases (EC [1,2]. Fungi and bacteria produces a spectrum of cellulolytic enzymes (cellulases) and xylanases which, on the basis of sequence similarities, can be classified into families. One of these families is known as the cellulase family D [3] or as the glycosyl hydrolases family 8 [4,E1]. The enzymes which are currently known to belong to this family are listed below.

  • Acetobacter xylinum endonuclease cmcAX.
  • Bacillus strain KSM-330 acidic endonuclease K (Endo-K).
  • Cellulomonas josui endoglucanase 2 (celB).
  • Cellulomonas uda endoglucanase.
  • Clostridium cellulolyticum endoglucanases C (celcCC).
  • Clostridium thermocellum endoglucanases A (celA).
  • Erwinia chrysanthemi minor endoglucanase y (celY).
  • Bacillus circulans β-glucanase (EC
  • Escherichia coli hypothetical protein yhjM.

The most conserved region in these enzymes is a stretch of about 20 residues that contains two conserved aspartate. The first asparatate is thought [5] to act as the nucleophile in the catalytic mechanism. We have used this region as a signature pattern.

Expert(s) to contact by email:

Henrissat B.

Last update:

November 1997 / Text revised.


Technical section

PROSITE method (with tools and information) covered by this documentation:

GLYCOSYL_HYDROL_F8, PS00812; Glycosyl hydrolases family 8 signature  (PATTERN)


1AuthorsBeguin P.
TitleMolecular biology of cellulose degradation.
SourceAnnu. Rev. Microbiol. 44:219-248(1990).
PubMed ID2252383

2AuthorsGilkes N.R. Henrissat B. Kilburn D.G. Miller R.C. Jr. Warren R.A.J.
TitleDomains in microbial beta-1, 4-glycanases: sequence conservation, function, and enzyme families.
SourceMicrobiol. Rev. 55:303-315(1991).
PubMed ID1886523

3AuthorsHenrissat B. Claeyssens M. Tomme P. Lemesle L. Mornon J.-P.
TitleCellulase families revealed by hydrophobic cluster analysis.
SourceGene 81:83-95(1989).
PubMed ID2806912

4AuthorsHenrissat B.
TitleA classification of glycosyl hydrolases based on amino acid sequence similarities.
SourceBiochem. J. 280:309-316(1991).
PubMed ID1747104

5AuthorsAlzari P.M. Souchon H. Dominguez R.
TitleThe crystal structure of endoglucanase CelA, a family 8 glycosyl hydrolase from Clostridium thermocellum.
SourceStructure 4:265-275(1996).
PubMed ID8805535


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