The Quaternary Structure of a Glycoside Hydrolase Dictates Specificity toward ß-Glucans.
J Biol Chem
; 291(13): 7183-94, 2016 Mar 25.
Article
en En
| MEDLINE
| ID: mdl-26755730
In the Carbohydrate-Active Enzyme (CAZy) database, glycoside hydrolase family 5 (GH5) is a large family with more than 6,000 sequences. Among the 51 described GH5 subfamilies, subfamily GH5_26 contains members that display either endo-ß(1,4)-glucanase or ß(1,3;1,4)-glucanase activities. In this study, we focused on the GH5_26 enzyme fromSaccharophagus degradans(SdGluc5_26A), a marine bacterium known for its capacity to degrade a wide diversity of complex polysaccharides.SdGluc5_26A displays lichenase activity toward ß(1,3;1,4)-glucans with a side cellobiohydrolase activity toward ß(1,4)-glucans. The three-dimensional structure ofSdGluc5_26A adopts a stable trimeric quaternary structure also observable in solution. The N-terminal region ofSdGluc5_26A protrudes into the active site of an adjacent monomer. To understand whether this occupation of the active site could influence its activity, we conducted a comprehensive enzymatic characterization ofSdGluc5_26A and of a mutant truncated at the N terminus. Ligand complex structures and kinetic analyses reveal that the N terminus governs the substrate specificity ofSdGluc5_26A. Its deletion opens the enzyme cleft at the -3 subsite and turns the enzyme into an endo-ß(1,4)-glucanase. This study demonstrates that experimental approaches can reveal structure-function relationships out of reach of current bioinformatic predictions.
Palabras clave
Texto completo:
1
Colección:
01-internacional
Base de datos:
MEDLINE
Asunto principal:
Proteínas Bacterianas
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Gammaproteobacteria
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Celulosa 1,4-beta-Celobiosidasa
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Beta-Glucanos
/
Glicósido Hidrolasas
Tipo de estudio:
Prognostic_studies
Idioma:
En
Revista:
J Biol Chem
Año:
2016
Tipo del documento:
Article
País de afiliación:
Francia
Pais de publicación:
Estados Unidos