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Substrate binding of a GH5 endoglucanase from the ruminal fungus Piromyces rhizinflata.
- Source :
- Acta Crystallographica: Section F (Wiley-Blackwell); Oct2011, Vol. 67 Issue 10, p1189-1194, 6p
- Publication Year :
- 2011
-
Abstract
- The endoglucanase EglA from Piromyces rhizinflata found in cattle stomach belongs to the GH5 family of glycoside hydrolases. The crystal structure of the catalytic domain of EglA shows the (β/α)<subscript>8</subscript>-barrel fold typical of GH5 enzymes. Adjacent to the active site of EglA, a loop containing a disulfide bond not found in other similar structures may participate in substrate binding. Because the active site was blocked by the N-terminal His tag of a neighbouring protein molecule in the crystal, enzyme-substrate complexes could not be obtained by soaking but were prepared by cocrystallization. The E154A mutant structure with a cellotriose bound to the −3, −2 and −1 subsites shows an extensive hydrogen-bonding network between the enzyme and the substrate, along with a stacking interaction between Trp44 and the −3 sugar. A possible dimer was observed in the crystal structure, but retention of activity in the E242A mutant suggested that the enzyme probably does not function as a dimer in solution. On the other hand, the first 100 amino acids encoded by the original cDNA fragment are very similar to those in the last third of the (β/α)<subscript>8</subscript>-barrel fold, indicating that EglA comprises at least two catalytic domains acting in tandem. [ABSTRACT FROM AUTHOR]
- Subjects :
- CATTLE diseases
FUNGI
GLYCOSIDASES
ENZYMES
CRYSTAL structure
CELLULOSE
BIOPOLYMERS
Subjects
Details
- Language :
- English
- ISSN :
- 17443091
- Volume :
- 67
- Issue :
- 10
- Database :
- Complementary Index
- Journal :
- Acta Crystallographica: Section F (Wiley-Blackwell)
- Publication Type :
- Academic Journal
- Accession number :
- 67343824
- Full Text :
- https://doi.org/10.1107/S1744309111032428