Poster: Organelle Biogenesis

Abs # 1155: Zein Protein Interactions

Presenter:	Randall, Jennifer , jrandall@nmsu.edu
Authors	Randall, Jennifer  (A)   Kemp, John D (A)
Affiliations:	(A): New Mexico State University

Zeins are alcohol soluble seed storage proteins found in the endosperm of maize. Two classes of zein proteins, the beta and delta zeins are unusually high in methionine. The genes encoding the beta and delta zeins have been introduced into tobacco in the hope of improving the nutritional quality of plants. These transgenic plants accumulating the beta or delta zein protein produce novel protein bodies in their leaves. The biogenesis of these protein bodies is unknown. It has been postulated that the protein bodies are derived in the endoplasmic reticulum (ER) as they are in maize. It is our belief that the beta and delta zein proteins have inherent properties due to their tertiary structures that allow them to interact with specific proteins and complexes which lead to the formation of ER derived protein bodies. It is not known how zein proteins are retained in the ER given that they do not contain known ER retention motifs. It has been postulated that zeins are retained in the ER by their association with BiP. BiP accumulation in transgenic plants does increase in plants accumulating the beta or delta zeins (Randall, 2000). The E. Coli two-hybrid system was used to demonstrate protein-protein interaction between the zein proteins and BiP (blp4 from tobacco). Mutations in both zein genes were made to “knock-out” putative BiP binding motifs. Analysis of these BiP binding “knock-outs” will be presented. An Arabadopsis expression library is currently being screened to reveal other proteins that interact with zeins. Results from this screen will be presented.