1qi2
From Proteopedia
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| , resolution 1.750Å | |||||||
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| Ligands: | , | ||||||
| Activity: | Cellulase, with EC number 3.2.1.4 | ||||||
| Related: | 1QHZ, 1QI0
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| Resources: | FirstGlance, OCA, PDBsum, RCSB | ||||||
| Coordinates: | save as pdb, mmCIF, xml | ||||||
ENDOGLUCANASE CEL5A FROM BACILLUS AGARADHAERENS IN THE TETRAGONAL CRYSTAL FORM IN COMPLEX WITH 2',4'-DINITROPHENYL 2-DEOXY-2-FLUORO-B-D-CELLOTRIOSIDE
Overview
Glycoside hydrolases are ubiquitous enzymes involved in a diverse array of biological processes, from the breakdown of biomass, through to viral invasion and cellular signalling. Endoglucanase Cel5A from Bacillus agaradhaerens, classified into glycoside hydrolase family 5, has been studied in a catalytically inactive crystal form at low pH conditions, in which native and complex structures revealed the importance of ring distortion during catalysis. Here, we present the structure of Cel5A in a new crystal form obtained at higher pH values in which the enzyme is active "in-crystal". Native, cellotriosyl-enzyme intermediate and beta-d-cellobiose structures were solved at 1.95, 1.75 and 2.1 A resolution, respectively. These structures reveal two classes of conformational change: those caused by crystal-packing and pH, with others induced upon substrate binding. At pH 7 a histidine residue, His206, implicated in substrate-binding and catalysis, but previously far removed from the substrate-binding cleft, moves over 10 A into the active site cleft in order to interact with the substrate in the +2 subsite. Occupation of the -1 subsite by substrate induces a loop closure to optimise protein-ligand interactions. Cel5A, along with the unrelated family 45 and family 6 cellulases, provides further evidence of substantial conformational change in response to ligand binding for this class of hydrolytic enzyme.
About this Structure
1QI2 is a Single protein structure of sequence from Bacillus agaradhaerens. Full crystallographic information is available from OCA.
Reference
Insights into ligand-induced conformational change in Cel5A from Bacillus agaradhaerens revealed by a catalytically active crystal form., Varrot A, Schulein M, Davies GJ, J Mol Biol. 2000 Mar 31;297(3):819-28. PMID:10731432
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