{PDOC00640}
{PS00812; GLYCOSYL_HYDROL_F8}
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* Glycosyl hydrolases family 8 signature *
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The microbial degradation  of cellulose and  xylans requires  several types of
enzymes such as endoglucanases (EC 3.2.1.4),  cellobiohydrolases (EC 3.2.1.91)
(exoglucanases), or xylanases (EC 3.2.1.8) [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 beta-glucanase (EC 3.2.1.73).
 - 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.

-Consensus pattern: A-[ST]-D-[AG]-D-x(2)-[IM]-A-x-[SA]-[LIVM]-[LIVMG]-x-A-
                    x(3)-[FW]
                    [The first D is an active site residue]
-Sequences known to belong to this class detected by the pattern: ALL.
-Other sequence(s) detected in Swiss-Prot: NONE.

-Expert(s) to contact by email:
           Henrissat B.; bernie@afmb.cnrs-mrs.fr

-Last update: November 1997 / Text revised.

[ 1] Beguin P.
     "Molecular biology of cellulose degradation."
     Annu. Rev. Microbiol. 44:219-248(1990).
     PubMed=2252383; DOI=10.1146/annurev.mi.44.100190.001251
[ 2] Gilkes N.R., Henrissat B., Kilburn D.G., Miller R.C. Jr., Warren R.A.J.
     "Domains in microbial beta-1, 4-glycanases: sequence conservation,
     function, and enzyme families."
     Microbiol. Rev. 55:303-315(1991).
     PubMed=1886523
[ 3] Henrissat B., Claeyssens M., Tomme P., Lemesle L., Mornon J.-P.
     "Cellulase families revealed by hydrophobic cluster analysis."
     Gene 81:83-95(1989).
     PubMed=2806912
[ 4] Henrissat B.
     "A classification of glycosyl hydrolases based on amino acid sequence
     similarities."
     Biochem. J. 280:309-316(1991).
     PubMed=1747104
[ 5] Alzari P.M., Souchon H., Dominguez R.
     "The crystal structure of endoglucanase CelA, a family 8 glycosyl
     hydrolase from Clostridium thermocellum."
     Structure 4:265-275(1996).
     PubMed=8805535
[E1] http://www.expasy.org/cgi-bin/lists?glycosid.txt

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