2ADD

Crystal structure of fructan 1-exohydrolase IIa from Cichorium intybus in complex with sucrose

Summary for 2ADD

• Entry DOI: 10.2210/pdb2add/pdb
• Related: 2ADE 2AEY 2AEZ
• Related PRD ID: PRD_900003
• Descriptor: fructan 1-exohydrolase IIa, alpha-D-mannopyranose-(1-4)-2-acetamido-2-deoxy-beta-D-glucopyranose-(1-4)-2-acetamido-2-deoxy-beta-D-glucopyranose, 2-acetamido-2-deoxy-beta-D-glucopyranose-(1-4)-2-acetamido-2-deoxy-beta-D-glucopyranose, ... (5 entities in total)
• Functional Keywords: five fold beta propeller, hydrolase
• Biological source: Cichorium intybus (chicory)
• Total number of polymer chains: 1
• Total formula weight: 62469.20

Authors

Verhaest, M.,Le Roy, K.,De Ranter, C.J.,Van Laere, A.,Van den Ende, W.,Rabijns, A. (deposition date: 2005-07-20, release date: 2006-08-29, Last modification date: 2024-10-16)

Primary citation

Verhaest, M.,Lammens, W.,Le Roy, K.,De Ranter, C.J.,Van Laere, A.,Rabijns, A.,Van den Ende, W.
Insights into the fine architecture of the active site of chicory fructan 1-exohydrolase: 1-kestose as substrate vs sucrose as inhibitor.
New Phytol, 174:90-100, 2007

PubMed Abstract: * Invertases and fructan exohydrolases (FEHs) fulfil important physiological functions in plants. Sucrose is the typical substrate for invertases and bacterial levansucrases but not for plant FEHs, which are usually inhibited by sucrose. * Here we report on complexes between chicory (Cichorium intybus) 1-FEH IIa with the substrate 1-kestose and the inhibitors sucrose, fructose and 2,5 dideoxy-2,5-imino-D-mannitol. Comparisons with other family GH32 and 68 enzyme-substrate complexes revealed that sucrose can bind as a substrate (invertase/levansucrase) or as an inhibitor (1-FEH IIa). * Sucrose acts as inhibitor because the O2 of the glucose moiety forms an H-linkage with the acid-base catalyst E201, inhibiting catalysis. By contrast, the homologous O3 of the internal fructose in the substrate 1-kestose forms an intramolecular H-linkage and does not interfere with the catalytic process. Mutagenesis showed that W82 and S101 are important for binding sucrose as inhibitor. * The physiological implications of the essential differences in the active sites of FEHs and invertases/levansucrases are discussed. Sucrose-inhibited FEHs show a K(i) (inhibition constant) well below physiological sucrose concentrations and could be rapidly activated under carbon deprivation.

PubMed: 17335500
DOI: 10.1111/j.1469-8137.2007.01988.x

Experimental method

X-RAY DIFFRACTION (2.5 Å)