Role of Molecular Chaperone in Wheat Storage Protein Assembly

Following sequestration into the ER, wheat gliadins assemble into complexes that initiate the formation of protein bodies. In the present work we have characterized the DNA sequence and regulation of expression of a plant BiP and also studied its interaction with wheat storage proteins as well as its role in the maturation of these storage proteins. In the Israeli lab, immunoprecipitation studies were made using anti BiP and anti storage proteins sera, both in wheat and in transgenic tobacco plants expressing a wheat gliadin storage proteins. In both cases, we could show that BiP interacts with the gliadin storage proteins. In addition, we could show that BiP also played an important role in the initial assembly of the gliadins. In the American lab, the complexity, structure and properties of tomato BiP was characterized at the molecular and biochemical levels. In addition, tomato BiP was also overexpressed in bacteria and the overexpressed protein was found to be active. The cooperative findings of the Israeli and American labs clearly improves our understanding of the structure and expression of a plant BiP as well as its role in the maturation of storage proteins in plants seeds. In addition, it will serve as a foundation for future studies of the mechanisms of BiP function in in vitro studies using purified storage proteins and purified recombinant active BiP.