Diversification of 13S globulins, allergenic seed storage proteins, of common buckwheat
2014
Sano, Madoka | Nakagawa, Mariko | Oishi, Akifumi | Yasui, Yasuo | Katsube-Tanaka, Tomoyuki
The α polypeptide of the 13S globulin subunit of common buckwheat is the counterpart of the major allergenic β polypeptide. Trypsin digestibility varies between variants of the α polypeptide with and without a tandem repeat insert. To evaluate the intra-species diversity of 13S globulin, the comprehensive screening of a genomic DNA library was performed, resulting in the isolation of 14 and 3 genes for Met-poor and Met-rich subunits, respectively. Although most tandem repeat units were 45bp in length, the two-repeat gene Glb2B and all one-repeat genes contained an additional 3bp. Secondary structure predictions and polyacrylamide gel electrophoresis demonstrated that the sense strand of Glb2B-CCG, the additional 3bp-deletion clone of Glb2B, formed a more rigid secondary structure than that of the wild-type. Thus, the large intra-species variation of 13S globulin revealed in this study and its diversification might be attributable to the unique nature of the tandem repeat sequences.
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