Construction of novel wheat high-M(r) glutenin subunit gene variability: Modification of the repetitive domain and expression in E-coli

We report the construction of modified high M(r) glutenin subunit genes with variable lengths of the repetitive domain and their expression in Escherichia coli. The modified glutenin subunits showed anomalously slow migration by SDS-PAGE characteristic of these polypeptides. Changes in the size of the repetitive domain correlated with both the migration behaviour on SDS-PAGE and with the surface hydrophobicities of the polypeptides measured by RP-HPLC. These constructs made it possible to obtain direct evidence for the first time that the anomalous electrophoretic mobilities of high M(r) glutenin subunits in SDS-PAGE, compared with globular proteins, are mainly due to the repetitive domain. These constructs should be useful for establishing the role of the repetitive domain of high,I, glutenin subunits in determining the viscoelastic properties of dough. They also offer the possibility of creating new genetic variability For wheat improvement. (C) 1997 Academic Press Limited