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- Title
Cloning, gene mapping, and functional analysis of a fructan 1-exohydrolase (1-FEH) from Lolium perenne implicated in fructan synthesis rather than in fructan mobilization.
- Authors
Lothier, Jérémy; Lasseur, Bertrand; Le Roy, Katrien; Van Laere, André; Prud'homme, Marie-Pascale; Barre, Philippe; Van den Ende, Wim; Morvan-Bertrand, Annette
- Abstract
Fructans, which are β-(2,1) and/or β-(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 β-(2,1) trimming enzyme acting during fructan synthesis in concert with fructan synthesis enzymes.
- Subjects
PLANT growth; PLANT development; FRUCTANS; AMINO acids; RYEGRASSES
- Publication
Journal of Experimental Botany, 2007, Vol 58, Issue 8, p1969
- ISSN
0022-0957
- Publication type
Article
- DOI
10.1093/jxb/erm053