2015 Volume 62 Issue 2 Pages 65-72
Edible burdock (Arctium lappa L.) accumulates an inulin-type fructan. Inulin-type fructan in plant has been hydrolyzed by fructan 1-exohydrolases (1-FEH). We have previously reported on the cloning of aleh1, which encodes a 1-FEH in edible burdock. Here, we describe the cloning of aleh2, which encodes a 1-FEH isozyme in edible burdock, and the functional analysis of the recombinant protein of aleh2 (rAlEH2) that displays properties different from the aleh1 recombinant protein. A cDNA, named aleh2, was obtained by the RACE. The rAlEH2, which was produced by Pichia pastoris, showed 1-FEH activity. Unlike the recombinant protein of aleh1, the rAlEH2 is a 1-FEH enzyme that efficiently hydrolyzes longer-chain fructans than 1-kestose, such as nystose, fructosylnystose and inulin. The expression study in burdock revealed the induction of aleh1 and aleh2 genes by low temperature. These findings indicated that two 1-FEH isoforms were involved in the degradation of the fructan in burdock roots during low-temperature storage.
Journal of the Technological Society of Starch
