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Purification, cloning and functional characterization of a fructan 6-exohydrolase from wheat (Triticum aestivum L.)


Van Riet, Liesbet; Nagaraj, Vinay; Van den Ende, Wim; Clerens, Stefan; Wiemken, Andres; Van Laere, André (2006). Purification, cloning and functional characterization of a fructan 6-exohydrolase from wheat (Triticum aestivum L.). Journal of Experimental Botany, 57(1):213-223.

Abstract

Fructans, β2-1 and/or β2-6 linked polymers of fructose, are produced by fructosyltransferases (FTs) from sucrose. They are important storage carbohydrates in many plants. Fructan reserves, widely distributed in plants, are believed to be mobilized via fructan exohydrolases (FEHs). The purification, cloning, and functional characterization of a 6-FEH from wheat (Triticum aestivum L.) are reported here. It is the first FEH shown to hydrolyse exclusively β2-6 bonds found in a fructan-producing plant. The enzyme was purified to homogeneity using ammonium sulphate precipitation, ConA affinity-, ion exchange-, and size exclusion chromatography and yielded a single band of 70 kDa following SDS-PAGE. Sequence information obtained by mass spectrometry of in-gel trypsin digests demonstrated the presence of a single protein. Moreover, these unique peptide sequences, together with some ESTs coding for them, could be used in a RT-PCR based strategy to clone a 1.7 kb cDNA. Functionality tests of the cDNA performed after heterologous expression in the yeast Pichia pastoris showed—as did the native enzyme from wheat—a very high activity of the produced protein against bacterial levan, 6-kestose, and phlein whilst sucrose and inulin were not used as substrates. Therefore the enzyme is a genuine 6-FEH. In contrast to most FEHs from fructan-accumulating plants, this FEH is not inhibited by sucrose. The relative abundance of 6-FEH transcripts in various tissues of wheat was investigated using quantitative RT-PCR

Abstract

Fructans, β2-1 and/or β2-6 linked polymers of fructose, are produced by fructosyltransferases (FTs) from sucrose. They are important storage carbohydrates in many plants. Fructan reserves, widely distributed in plants, are believed to be mobilized via fructan exohydrolases (FEHs). The purification, cloning, and functional characterization of a 6-FEH from wheat (Triticum aestivum L.) are reported here. It is the first FEH shown to hydrolyse exclusively β2-6 bonds found in a fructan-producing plant. The enzyme was purified to homogeneity using ammonium sulphate precipitation, ConA affinity-, ion exchange-, and size exclusion chromatography and yielded a single band of 70 kDa following SDS-PAGE. Sequence information obtained by mass spectrometry of in-gel trypsin digests demonstrated the presence of a single protein. Moreover, these unique peptide sequences, together with some ESTs coding for them, could be used in a RT-PCR based strategy to clone a 1.7 kb cDNA. Functionality tests of the cDNA performed after heterologous expression in the yeast Pichia pastoris showed—as did the native enzyme from wheat—a very high activity of the produced protein against bacterial levan, 6-kestose, and phlein whilst sucrose and inulin were not used as substrates. Therefore the enzyme is a genuine 6-FEH. In contrast to most FEHs from fructan-accumulating plants, this FEH is not inhibited by sucrose. The relative abundance of 6-FEH transcripts in various tissues of wheat was investigated using quantitative RT-PCR

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Item Type:Journal Article, refereed, original work
Communities & Collections:National licences > 142-005
Dewey Decimal Classification:Unspecified
Scopus Subject Areas:Life Sciences > Physiology
Life Sciences > Plant Science
Language:English
Date:1 January 2006
Deposited On:02 Nov 2018 07:06
Last Modified:15 Apr 2021 14:50
Publisher:Oxford University Press
ISSN:0022-0957
OA Status:Green
Free access at:Publisher DOI. An embargo period may apply.
Publisher DOI:https://doi.org/10.1093/jxb/erj031

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