Title: Creating S-type characteristics in the F-type enzyme fructan:fructan 1-fructosyltransferase of Triticum aestivum L
Authors: Schroeven, Lindsey ×
Lammens, Willem
Kawakami, Akira
Yoshida, Midori
Van Laere, André
Van den Ende, Wim #
Issue Date: Sep-2009
Publisher: Oxford University Press
Series Title: Journal of Experimental Botany vol:60 issue:13 pages:3687-3696
Abstract: Invertases cleave sucrose in glucose and fructose, using water as an acceptor. Fructosyltransferases catalyse the transfer of a fructosyl residue between sucrose and/or fructan molecules. Plant fructosyltransferases (FTs) evolved from vacuolar invertases by small mutational changes, leading to differences in substrate specificity. The S-type of enzymes (invertases, sucrose:sucrose 1-fructosyltransferases or 1-SSTs, and sucrose:fructan 6-fructosyltransferases or 6-SFTs) prefer sucrose as the donor substrate while F-type enzymes (fructan:fructan 1-fructosyltransferases or 1-FFTs and fructan:fructan 6(G)-fructosyltransferases or 6(G)-FFTs) preferentially use fructan as the donor substrate. Recently, a functional Asp/Arg or Asp/Lys couple in the Hypervariable Loop (HVL) was suggested to be essential to keep Asp in a favourable orientation for binding sucrose as the donor substrate in S-type enzymes. However, the F-type enzyme 1-FFT of Triticum aestivum (Ta1-FFT) also contains the Asp/Arg couple in the HVL, although it prefers fructan as the donor substrate. In this paper, mutagenesis studies on Ta1-FFT are presented. In Ta1-SST, Tyr282 (the Asp281 homologue) seems to be essential in creating a tight H-bond Network (HBN) in which the Arg-residue of the Asp/Arg couple is held in a fixed position. This tight HBN is disrupted in Ta1-FFT, leading to a more flexible Arg-residue and a dysfunctional Asp/Arg couple. A single D281Y mutation in Ta1-FFT restored the tight HBN and introduced typical S-type characteristics. Conclusively, in wheat FTs Asp281 (and its homologues) is involved in donor substrate specificity.
ISSN: 0022-0957
Publication status: published
KU Leuven publication type: IT
Appears in Collections:Molecular Physiology of Plants and Micro-organisms Section - miscellaneous
Laboratory for Molecular Plant Physiology (-)
× corresponding author
# (joint) last author

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