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Title: Unexpected presence of graminan- and levan-type fructans in the evergreen frost-hardy eudicot Pachysandra terminalis (Buxaceae). Purification, cloning and functional analysis of a 6-SST/6-SFT enzyme
Authors: Van den Ende, Wim ×
Coopman, Marlies
Clerens, Stefan
Vergauwen, Rudolf
Le Roy, Katrien
Lammens, Willem
Van Laere, André #
Issue Date: Jan-2011
Publisher: American Society of Plant Biologists
Series Title: Plant Physiology vol:155 issue:1 pages:603-614
Abstract: About 15% of flowering plants accumulate fructans. Inulin-type fructans with β(2,1) fructosyl linkages typically accumulate in the core eudicot families (eg Asteraceae), while levan-type fructans with β(2,6) linkages and branched, graminan-type fructans with mixed linkages predominate in monocot families. Here, we describe the unexpected finding that graminan and levan-type fructans, as typically occurring in wheat and barley, also accumulate in Pachysandra terminalis, an evergreen, frost-hardy basal eudicot species. Part of the complex graminan- and levan-type fructans as accumulating in vivo can be produced in vitro by a sucrose: fructan 6-fructosyltransferase (6-SFT) enzyme with inherent sucrose: sucrose 6-fructosyltransferase (6-SST) activity, and some minor 1-SST activity. This enzyme produces a series of cereal-like graminan- and levan-type fructans from sucrose as a single substrate. The 6-SST/6-SFT enzyme was fully purified by classic column chromatography. In-gel trypsin digestion led to RT-PCR based cDNA cloning. The functionality of the 6-SST/6-SFT cDNA was demonstrated after heterologous expression in Pichia pastoris. Both the recombinant and native enzymes showed rather similar substrate specificity characteristics, including peculiar temperature-dependent inherent 1-SST and 6-FEH side activities. The finding that cereal-type fructans accumulate in a basal eudicot species further confirms the polyphyletic origin of fructan biosynthesis in nature. Our data suggest that the fructan syndrome in Pachysandra terminalis can be considered as a recent evolutionary event. Putative connections between abiotic stress and fructans are discussed.
ISSN: 0032-0889
Publication status: published
KU Leuven publication type: IT
Appears in Collections:Molecular Physiology of Plants and Micro-organisms Section - miscellaneous
Biology, Campus Kulak Kortrijk
Laboratory for Molecular Plant Physiology (-)
× corresponding author
# (joint) last author

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