Reference "Purification, cloning, and functional expression of sucrose:fructan 6-fructosyltransferase, a key enzyme of fructan synthesis in barley"

Reference ID

8897

Title

Purification, cloning, and functional expression of sucrose:fructan 6-fructosyltransferase, a key enzyme of fructan synthesis in barley

Source

Proceedings of the National Academy of Sciences of the United States of America, 1995, vol. 92, pp. 11652-11656

Authors (5)

Sprenger-N	Bortlik-K
Brandt-A	Boller-T
Wiemken-A

Abstract

Fructans play an important role in assimilate partitioning and possibly in
stress tolerance in many plant families. Sucrose:fructan 6-fructosyltransferase
(6-SFT), an enzyme catalyzing the formation and extension of beta-2,6-linked
fructans typical of grasses, was purified from barley (Hordeum vulgare L.). It
occurred in two closely similar isoforms with indistinguishable catalytic
properties, both consisting of two subunits with apparent masses of 49 and 23
kDa. Oligonucleotides, designed according to the sequences of tryptic peptides
from the large subunit, were used to amplify corresponding sequences from barley
cDNA. The main fragment generated was cloned and used to screen a barley cDNA
expression library. The longest cDNA obtained was transiently expressed in
Nicotiana plumbaginifolia protoplasts and shown to encode a functional 6-SFT.
The deduced amino acid sequence of the cDNA comprises both subunits of 6-SFT. It
has high similarity to plant invertases and other beta-fructosyl hydrolases but
only little to bacterial fructosyltransferases catalyzing the same type of
reaction as 6-SFT.