Journal Article

Scopolin-hydrolyzing β-glucosidases in roots of Arabidopsis

Young Ock Ahn, Bun-ichi Shimizu, Kanzo Sakata, Dashzeveg Gantulga, Zhanghe Zhou, David R. Bevan and Asim Esen

in Plant and Cell Physiology

Published on behalf of Japanese Society of Plant Physiologists

Volume 51, issue 1, pages 132-143
Published in print January 2010 | ISSN: 0032-0781
Published online December 2009 | e-ISSN: 1471-9053 | DOI:
Scopolin-hydrolyzing β-glucosidases in roots of Arabidopsis

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  • Biochemistry
  • Molecular and Cell Biology
  • Plant Sciences and Forestry


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Three β-glucosidases (At1g66270-BGLU21, At1g66280-BGLU22, and At3g09260-BGLU23) were purified from the roots of Arabidopsis and their cDNAs were expressed in insect cells. In addition, two β-glucosidase binding protein cDNAs (At3g16420; PBPI and At3g16430; PBPII) were expressed in Escherichia coli and their protein products purified. These binding proteins interact with β-glucosidases and activate them. BGLU21, 22 and 23 hydrolyzed the natural substrate scopolin specifically and also hydrolyzed to some extent substrates whose aglycone moiety is similar to scopolin (e.g. esculin and 4-MU-glucoside). In contrast, they hydrolyzed poorly DIMBOA-glucoside and did not hydrolyze pNP- and oNP-glucosides. We determined the physicochemical properties of native and recombinant BGLUs, and found no differences between them. They were stable in a narrow pH range (5–7.5) and had temperature and pH optima for activity at 35°C and pH 5.5, respectively. As for thermostability, >95% of their activity was retained at 40°C but dramatically decreased at >50°C. The apparent Km of native and recombinant enzymes for scopolin was 0.73 and 0.81 mM, respectively, and it was 5.8 and 9.7 mM, respectively, for esculin. Western blot analysis showed that all three enzymes were exclusively expressed in roots of seedlings but not in any other plant part or organ under normal conditions. Furthermore, spatial expression patterns of all eight genes belonging to subfamily 3 were investigated at the transcription level by RT–PCR.

Keywords: Arabidopsis thaliana; Coumarins; β-Glucosidases; Glycoside hydrolase family 1; Scopolin; Scopoletin

Journal Article.  6798 words.  Illustrated.

Subjects: Biochemistry ; Molecular and Cell Biology ; Plant Sciences and Forestry

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