BACKGROUND: Cellulases, which catalyze the hydrolysis of glycosidic bonds in cellulose, can be classified into several different protein families. Endoglucanase CelA is a member of glycosyl hydrolase family 8, a family for which no structural information was previously available. RESULTS: The crystal structure of CelA was determined by multiple isomorphous replacement and refined to 1.65 A resolution. The protein folds into a regular (alpha/alpha)6 barrel formed by six inner and six outer alpha helices. Cello-oligosaccharides bind to an acidic cleft containing at least five D-glucosyl-binding subsites (A-E) such that the scissile glycosidic linkage lies between subsites C and D. The strictly conserved residue Glu95, which occupies the center of the substrate-binding cleft and is hydrogen bonded to the glycosidic oxygen, has been assigned the catalytic role of proton donor. CONCLUSIONS: The present analysis provides a basis for modeling homologous family 8 cellulases. The architecture of the active-site cleft, presenting at least five glucosyl-binding subsites, explains why family 8 cellulases cleave cello-oligosaccharide polymers that are at least five D-glycosyl subunits long. Furthermore, the structure of CelA allows comparison with (alpha/alpha)6 barrel glycosidases that are not related in sequence, suggesting a possible, albeit distant, evolutionary relationship between different families of glycosyl hydrolases.
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http://purl.uniprot.org/cit... | rdf:type | uniprot:Journal_Citation | lld:uniprot |
http://purl.uniprot.org/cit... | rdfs:comment | BACKGROUND: Cellulases, which catalyze the hydrolysis of glycosidic bonds in cellulose, can be classified into several different protein families. Endoglucanase CelA is a member of glycosyl hydrolase family 8, a family for which no structural information was previously available. RESULTS: The crystal structure of CelA was determined by multiple isomorphous replacement and refined to 1.65 A resolution. The protein folds into a regular (alpha/alpha)6 barrel formed by six inner and six outer alpha helices. Cello-oligosaccharides bind to an acidic cleft containing at least five D-glucosyl-binding subsites (A-E) such that the scissile glycosidic linkage lies between subsites C and D. The strictly conserved residue Glu95, which occupies the center of the substrate-binding cleft and is hydrogen bonded to the glycosidic oxygen, has been assigned the catalytic role of proton donor. CONCLUSIONS: The present analysis provides a basis for modeling homologous family 8 cellulases. The architecture of the active-site cleft, presenting at least five glucosyl-binding subsites, explains why family 8 cellulases cleave cello-oligosaccharide polymers that are at least five D-glycosyl subunits long. Furthermore, the structure of CelA allows comparison with (alpha/alpha)6 barrel glycosidases that are not related in sequence, suggesting a possible, albeit distant, evolutionary relationship between different families of glycosyl hydrolases. | lld:uniprot |
http://purl.uniprot.org/cit... | skos:exactMatch | http://purl.uniprot.org/med... | lld:uniprot |
http://purl.uniprot.org/cit... | skos:exactMatch | http://purl.uniprot.org/pub... | lld:uniprot |
http://purl.uniprot.org/cit... | uniprot:name | Structure | lld:uniprot |
http://purl.uniprot.org/cit... | uniprot:author | Alzari P.M. | lld:uniprot |
http://purl.uniprot.org/cit... | uniprot:author | Souchon H. | lld:uniprot |
http://purl.uniprot.org/cit... | uniprot:author | Dominguez R. | lld:uniprot |
http://purl.uniprot.org/cit... | uniprot:date | 1996 | lld:uniprot |
http://purl.uniprot.org/cit... | uniprot:pages | 265-275 | lld:uniprot |
http://purl.uniprot.org/cit... | uniprot:title | The crystal structure of endoglucanase CelA, a family 8 glycosyl hydrolase from Clostridium thermocellum. | lld:uniprot |
http://purl.uniprot.org/cit... | uniprot:volume | 4 | lld:uniprot |
http://purl.uniprot.org/cit... | dc-term:identifier | doi:10.1016/S0969-2126(96)00031-7 | lld:uniprot |
uniprot-protein:A3DC29 | uniprot:citation | http://purl.uniprot.org/cit... | lld:uniprot |
http://linkedlifedata.com/r... | rdf:object | http://purl.uniprot.org/cit... | lld:uniprot |