
doi: 10.1093/jxb/erm053
pmid: 17456505
Fructans, which are beta-(2,1) and/or beta-(2,6) linked polymers of fructose, are important storage carbohydrates in many plants. They are mobilized via fructan exohydrolases (FEHs). The cloning, mapping, and functional analysis of the first 1-FEH (EC 3.2.1.153) from Lolium perenne L. var. Bravo is described here. By screening a perennial ryegrass cDNA library, a 1-FEH cDNA named Lp1-FEHa was cloned. The Lp1-FEHa deduced protein has a low iso-electric point (5.22) and it groups together with plant FEHs and cell-wall type invertases. The deduced amino acid sequence shows 75% identity to wheat 1-FEH w2. The Lp1-FEHa gene was mapped at a distal position on the linkage group 3 (LG3). Functional characterization of the recombinant protein in Pichia pastoris demonstrated that it had high FEH activity towards 1-kestotriose, 1,1-kestotetraose, and inulin, but low activity against 6-kestotriose and levan. Like other fructan-plant FEHs, no hydrolase activity could be detected towards sucrose, convincingly demonstrating that the enzyme is not a classic invertase. The expression pattern analysis of Lp1-FEHa revealed transcript accumulation in leaf tissues accumulating fructans while transcript level was low in the photosynthetic tissues. The high expression level of this 1-FEH in conditions of active fructan synthesis, together with its low expression level when fructan contents are low, suggest that it might play a role as a beta-(2,1) trimming enzyme acting during fructan synthesis in concert with fructan synthesis enzymes.
Glycoside Hydrolases, PICHIA PASTORIS, Recombinant Fusion Proteins, Molecular Sequence Data, GENE MAPPING, [SDV.BV.BOT] Life Sciences [q-bio]/Vegetal Biology/Botanics, Lolium, Amino Acid Sequence, RNA, Messenger, Cloning, Molecular, Phylogeny, Plant Proteins, 580, RAY GRASS ANGLAIS, FRUCTAN EXOHYDROLASE, Base Sequence, Chromosome Mapping, Biological Transport, [SDV.BV.BOT]Life Sciences [q-bio]/Vegetal Biology/Botanics, Fructans, FRUCTAN BIOSYNTHESIS, Sequence Alignment
Glycoside Hydrolases, PICHIA PASTORIS, Recombinant Fusion Proteins, Molecular Sequence Data, GENE MAPPING, [SDV.BV.BOT] Life Sciences [q-bio]/Vegetal Biology/Botanics, Lolium, Amino Acid Sequence, RNA, Messenger, Cloning, Molecular, Phylogeny, Plant Proteins, 580, RAY GRASS ANGLAIS, FRUCTAN EXOHYDROLASE, Base Sequence, Chromosome Mapping, Biological Transport, [SDV.BV.BOT]Life Sciences [q-bio]/Vegetal Biology/Botanics, Fructans, FRUCTAN BIOSYNTHESIS, Sequence Alignment
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